Remove implied profanity from error messages. (#10270)

i.e. WTF, WTH.

core/src/main/java/org/apache/druid/guice/ConfigProvider.java

@@ -29,6 +29,7 @@ import org.skife.config.ConfigurationObjectFactory;
 import java.util.Map;
 
 /**
+ *
  */
 public class ConfigProvider<T> implements Provider<T>
 {
@@ -79,7 +80,7 @@ public class ConfigProvider<T> implements Provider<T>
   {
     try {
       // ConfigMagic handles a null replacements
-      Preconditions.checkNotNull(factory, "WTF!? Code misconfigured, inject() didn't get called.");
+      Preconditions.checkNotNull(factory, "Code misconfigured, inject() didn't get called.");
       return factory.buildWithReplacements(clazz, replacements);
     }
     catch (IllegalArgumentException e) {

core/src/main/java/org/apache/druid/java/util/common/io/smoosh/FileSmoosher.java

@@ -205,7 +205,7 @@ public class FileSmoosher implements Closeable
         bytesWritten += bytesWrittenInChunk;
 
         if (bytesWritten != currOut.getCurrOffset() - startOffset) {
-          throw new ISE("WTF? Perhaps there is some concurrent modification going on?");
+          throw new ISE("Perhaps there is some concurrent modification going on?");
         }
         if (bytesWritten > size) {
           throw new ISE("Wrote[%,d] bytes for something of size[%,d].  Liar!!!", bytesWritten, size);
@@ -228,7 +228,7 @@ public class FileSmoosher implements Closeable
         writerCurrentlyInUse = false;
 
         if (bytesWritten != currOut.getCurrOffset() - startOffset) {
-          throw new ISE("WTF? Perhaps there is some concurrent modification going on?");
+          throw new ISE("Perhaps there is some concurrent modification going on?");
         }
         if (bytesWritten != size) {
           throw new IOE("Expected [%,d] bytes, only saw [%,d], potential corruption?", size, bytesWritten);

core/src/main/java/org/apache/druid/java/util/common/logger/Logger.java

@@ -162,16 +162,6 @@ public class Logger
     log.error("ASSERTION_ERROR: " + message, formatArgs);
   }
 
-  public void wtf(String message, Object... formatArgs)
-  {
-    error(message, formatArgs);
-  }
-
-  public void wtf(Throwable t, String message, Object... formatArgs)
-  {
-    error(t, message, formatArgs);
-  }
-
   public void debugSegments(@Nullable final Collection<DataSegment> segments, @Nullable String preamble)
   {
     if (log.isDebugEnabled()) {

core/src/main/java/org/apache/druid/java/util/http/client/pool/ResourcePool.java

@@ -224,7 +224,7 @@ public class ResourcePool<K, V> implements Closeable
           deficit--;
           poolVal = null;
         } else {
-          throw new IllegalStateException("WTF?! No objects left, and no object deficit. This is probably a bug.");
+          throw new IllegalStateException("Unexpected state: No objects left, and no object deficit");
         }
       }
 

core/src/main/java/org/apache/druid/java/util/http/client/response/SequenceInputStreamResponseHandler.java

@@ -151,7 +151,7 @@ public class SequenceInputStreamResponseHandler implements HttpResponseHandler<I
       }
       catch (IOException e) {
         // This should never happen
-        log.wtf(e, "The empty stream threw an IOException");
+        log.error(e, "The empty stream threw an IOException");
         throw new RuntimeException(e);
       }
       finally {

core/src/main/java/org/apache/druid/timeline/partition/OvershadowableManager.java

@@ -287,6 +287,7 @@ class OvershadowableManager<T extends Overshadowable<T>>
    * @param minorVersion the minor version to check overshadow relation. The found groups will have lower minor versions
    *                     than this.
    * @param fromState    the state to search for overshadowed groups.
+   *
    * @return a list of found atomicUpdateGroups. It could be empty if no groups are found.
    */
   @VisibleForTesting
@@ -333,6 +334,7 @@ class OvershadowableManager<T extends Overshadowable<T>>
    * @param minorVersion the minor version to check overshadow relation. The found groups will have higher minor
    *                     versions than this.
    * @param fromState    the state to search for overshadowed groups.
+   *
    * @return a list of found atomicUpdateGroups. It could be empty if no groups are found.
    */
   @VisibleForTesting
@@ -530,7 +532,7 @@ class OvershadowableManager<T extends Overshadowable<T>>
             findOvershadows(group, State.STANDBY)
         );
         if (overshadowingStandbys.isEmpty()) {
-          throw new ISE("WTH? atomicUpdateGroup[%s] is in overshadowed state, but no one overshadows it?", group);
+          throw new ISE("Unexpected state: atomicUpdateGroup[%s] is overshadowed, but nothing overshadows it", group);
         }
         groupsOvershadowingAug = overshadowingStandbys;
         isOvershadowingGroupsFull = false;
@@ -585,6 +587,7 @@ class OvershadowableManager<T extends Overshadowable<T>>
    * @param groups               atomicUpdateGroups sorted by their rootPartitionRange
    * @param startRootPartitionId the start partitionId of the root partition range to check the coverage
    * @param endRootPartitionId   the end partitionId of the root partition range to check the coverage
+   *
    * @return true if the given groups fully cover the given partition range.
    */
   private boolean doGroupsFullyCoverPartitionRange(
@@ -675,7 +678,7 @@ class OvershadowableManager<T extends Overshadowable<T>>
             // If this chunk is already in the atomicUpdateGroup, it should be in knownPartitionChunks
             // and this code must not be executed.
             throw new ISE(
-                "WTH? chunk[%s] is in the atomicUpdateGroup[%s] but not in knownPartitionChunks[%s]?",
+                "Unexpected state: chunk[%s] is in the atomicUpdateGroup[%s] but not in knownPartitionChunks[%s]",
                 chunk,
                 atomicUpdateGroup,
                 knownPartitionChunks
@@ -875,7 +878,7 @@ class OvershadowableManager<T extends Overshadowable<T>>
 
     if (!removed.equals(aug)) {
       throw new ISE(
-          "WTH? actually removed atomicUpdateGroup[%s] is different from the one which is supposed to be[%s]",
+          "Unexpected state: Removed atomicUpdateGroup[%s] is different from expected atomicUpdateGroup[%s]",
           removed,
           aug
       );
@@ -896,7 +899,7 @@ class OvershadowableManager<T extends Overshadowable<T>>
 
     if (!knownChunk.equals(partitionChunk)) {
       throw new ISE(
-          "WTH? Same partitionId[%d], but known partition[%s] is different from the input partition[%s]",
+          "Unexpected state: Same partitionId[%d], but known partition[%s] is different from the input partition[%s]",
           partitionChunk.getChunkNumber(),
           knownChunk,
           partitionChunk
@@ -932,7 +935,8 @@ class OvershadowableManager<T extends Overshadowable<T>>
               (SingleEntryShort2ObjectSortedMap<AtomicUpdateGroup<T>>) map;
           //noinspection ConstantConditions
           return singleMap.val.isFull();
-        });
+        }
+    );
   }
 
   @Nullable

core/src/test/java/org/apache/druid/common/utils/IdUtilsTest.java

@@ -101,7 +101,7 @@ public class IdUtilsTest
   {
     expectedException.expect(IllegalArgumentException.class);
     expectedException.expectMessage("thingToValidate cannot contain whitespace character except space.");
-    IdUtils.validateId(THINGO, "wtf\u000Bis line tabulation");
+    IdUtils.validateId(THINGO, "what\u000Bis line tabulation");
   }
 
   @Test

extensions-contrib/ambari-metrics-emitter/src/main/java/org/apache/druid/emitter/ambari/metrics/AmbariMetricsEmitter.java

@@ -107,7 +107,7 @@ public class AmbariMetricsEmitter extends AbstractTimelineMetricsSink implements
   public void emit(Event event)
   {
     if (!started.get()) {
-      throw new ISE("WTF emit was called while service is not started yet");
+      throw new ISE("Emit called unexpectedly before service start");
     }
     if (event instanceof ServiceMetricEvent) {
       final TimelineMetric timelineEvent = timelineMetricConverter.druidEventToTimelineMetric((ServiceMetricEvent) event);

extensions-contrib/graphite-emitter/src/main/java/org/apache/druid/emitter/graphite/GraphiteEmitter.java

@@ -99,7 +99,7 @@ public class GraphiteEmitter implements Emitter
   public void emit(Event event)
   {
     if (!started.get()) {
-      throw new ISE("WTF emit was called while service is not started yet");
+      throw new ISE("Emit called unexpectedly before service start");
     }
     if (event instanceof ServiceMetricEvent) {
       final GraphiteEvent graphiteEvent = graphiteEventConverter.druidEventToGraphite((ServiceMetricEvent) event);

extensions-contrib/opentsdb-emitter/src/main/java/org/apache/druid/emitter/opentsdb/OpentsdbEmitter.java

@@ -66,7 +66,7 @@ public class OpentsdbEmitter implements Emitter
   public void emit(Event event)
   {
     if (!started.get()) {
-      throw new ISE("WTF emit was called while service is not started yet");
+      throw new ISE("Emit called unexpectedly before service start");
     }
     if (event instanceof ServiceMetricEvent) {
       OpentsdbEvent opentsdbEvent = converter.convert((ServiceMetricEvent) event);

extensions-core/druid-basic-security/src/main/java/org/apache/druid/security/basic/authorization/db/cache/CoordinatorPollingBasicAuthorizerCacheManager.java

@@ -206,7 +206,7 @@ public class CoordinatorPollingBasicAuthorizerCacheManager implements BasicAutho
       }
     }
     catch (Exception e) {
-      LOG.makeAlert(e, "WTF? Could not deserialize user/role map received from coordinator.").emit();
+      LOG.makeAlert(e, "Could not deserialize user/role map received from coordinator").emit();
     }
   }
 

extensions-core/druid-bloom-filter/src/main/java/org/apache/druid/query/aggregation/bloom/BloomFilterMergeAggregator.java

@@ -39,7 +39,7 @@ public final class BloomFilterMergeAggregator
     ByteBuffer other = selector.getObject();
     if (other == null) {
       // nulls should be empty bloom filters by this point, so encountering a nil column in merge agg is unexpected
-      throw new ISE("WTF?! Unexpected null value in BloomFilterMergeAggregator");
+      throw new ISE("Unexpected null value in BloomFilterMergeAggregator");
     }
     BloomKFilter.mergeBloomFilterByteBuffers(buf, buf.position(), other, other.position());
   }

extensions-core/druid-bloom-filter/src/main/java/org/apache/druid/query/aggregation/bloom/BloomFilterMergeAggregatorFactory.java

@@ -76,7 +76,7 @@ public class BloomFilterMergeAggregatorFactory extends BloomFilterAggregatorFact
     final BaseNullableColumnValueSelector selector = metricFactory.makeColumnValueSelector(fieldName);
     // null columns should be empty bloom filters by this point, so encountering a nil column in merge agg is unexpected
     if (selector instanceof NilColumnValueSelector) {
-      throw new ISE("WTF?! Unexpected NilColumnValueSelector");
+      throw new ISE("Unexpected NilColumnValueSelector");
     }
     return new BloomFilterMergeAggregator((ColumnValueSelector<ByteBuffer>) selector, getMaxNumEntries(), true);
   }

extensions-core/kafka-indexing-service/src/test/java/org/apache/druid/indexing/kafka/supervisor/KafkaSupervisorTest.java

@@ -2594,10 +2594,10 @@ public class KafkaSupervisorTest extends EasyMockSupport
     }
 
     Assert.assertTrue(
-        serviceEmitter.getStackTrace().startsWith("org.apache.druid.java.util.common.ISE: WTH?! cannot find")
+        serviceEmitter.getStackTrace().startsWith("org.apache.druid.java.util.common.ISE: Cannot find")
     );
     Assert.assertEquals(
-        "WTH?! cannot find taskGroup [0] among all activelyReadingTaskGroups [{}]",
+        "Cannot find taskGroup [0] among all activelyReadingTaskGroups [{}]",
         serviceEmitter.getExceptionMessage()
     );
     Assert.assertEquals(ISE.class, serviceEmitter.getExceptionClass());

extensions-core/kinesis-indexing-service/src/test/java/org/apache/druid/indexing/kinesis/supervisor/KinesisSupervisorTest.java

@@ -3194,9 +3194,9 @@ public class KinesisSupervisorTest extends EasyMockSupport
     }
 
     Assert.assertTrue(serviceEmitter.getStackTrace()
-                                    .startsWith("org.apache.druid.java.util.common.ISE: WTH?! cannot find"));
+                                    .startsWith("org.apache.druid.java.util.common.ISE: Cannot find"));
     Assert.assertEquals(
-        "WTH?! cannot find taskGroup [0] among all activelyReadingTaskGroups [{}]",
+        "Cannot find taskGroup [0] among all activelyReadingTaskGroups [{}]",
         serviceEmitter.getExceptionMessage()
     );
     Assert.assertEquals(ISE.class, serviceEmitter.getExceptionClass());

extensions-core/lookups-cached-single/src/main/java/org/apache/druid/server/lookup/PollingLookup.java

@@ -119,7 +119,7 @@ public class PollingLookup extends LookupExtractor
     }
     final CacheRefKeeper cacheRefKeeper = refOfCacheKeeper.get();
     if (cacheRefKeeper == null) {
-      throw new ISE("Cache reference is null WTF");
+      throw new ISE("Cache reference is null");
     }
     final PollingCache cache = cacheRefKeeper.getAndIncrementRef();
     try {

indexing-hadoop/src/main/java/org/apache/druid/indexer/DetermineHashedPartitionsJob.java

@@ -239,7 +239,8 @@ public class DetermineHashedPartitionsJob implements Jobby
 
       Map<String, Object> metrics = TaskMetricsUtils.makeIngestionRowMetrics(
           jobCounters.findCounter(HadoopDruidIndexerConfig.IndexJobCounters.ROWS_PROCESSED_COUNTER).getValue(),
-          jobCounters.findCounter(HadoopDruidIndexerConfig.IndexJobCounters.ROWS_PROCESSED_WITH_ERRORS_COUNTER).getValue(),
+          jobCounters.findCounter(HadoopDruidIndexerConfig.IndexJobCounters.ROWS_PROCESSED_WITH_ERRORS_COUNTER)
+                     .getValue(),
           jobCounters.findCounter(HadoopDruidIndexerConfig.IndexJobCounters.ROWS_UNPARSEABLE_COUNTER).getValue(),
           jobCounters.findCounter(HadoopDruidIndexerConfig.IndexJobCounters.ROWS_THROWN_AWAY_COUNTER).getValue()
       );
@@ -318,7 +319,7 @@ public class DetermineHashedPartitionsJob implements Jobby
                                                        .bucketInterval(DateTimes.utc(inputRow.getTimestampFromEpoch()));
 
         if (!maybeInterval.isPresent()) {
-          throw new ISE("WTF?! No bucket found for timestamp: %s", inputRow.getTimestampFromEpoch());
+          throw new ISE("No bucket found for timestamp: %s", inputRow.getTimestampFromEpoch());
         }
         interval = maybeInterval.get();
       }
@@ -387,7 +388,7 @@ public class DetermineHashedPartitionsJob implements Jobby
         Optional<Interval> intervalOptional = config.getGranularitySpec().bucketInterval(DateTimes.utc(key.get()));
 
         if (!intervalOptional.isPresent()) {
-          throw new ISE("WTF?! No bucket found for timestamp: %s", key.get());
+          throw new ISE("No bucket found for timestamp: %s", key.get());
         }
         interval = intervalOptional.get();
       }

indexing-hadoop/src/main/java/org/apache/druid/indexer/DeterminePartitionsJob.java

@@ -464,7 +464,7 @@ public class DeterminePartitionsJob implements Jobby
       final Optional<Interval> maybeInterval = config.getGranularitySpec().bucketInterval(timestamp);
 
       if (!maybeInterval.isPresent()) {
-        throw new ISE("WTF?! No bucket found for timestamp: %s", timestamp);
+        throw new ISE("No bucket found for timestamp: %s", timestamp);
       }
 
       final Interval interval = maybeInterval.get();
@@ -627,7 +627,7 @@ public class DeterminePartitionsJob implements Jobby
       final long totalRows = firstDvc.numRows;
 
       if (!"".equals(firstDvc.dim) || !"".equals(firstDvc.value)) {
-        throw new IllegalStateException("WTF?! Expected total row indicator on first k/v pair!");
+        throw new IllegalStateException("Expected total row indicator on first k/v pair");
       }
 
       // "iterator" will now take us over many candidate dimensions

indexing-hadoop/src/main/java/org/apache/druid/indexer/IndexGeneratorJob.java

@@ -355,7 +355,7 @@ public class IndexGeneratorJob implements Jobby
       final Optional<Bucket> bucket = getConfig().getBucket(inputRow);
 
       if (!bucket.isPresent()) {
-        throw new ISE("WTF?! No bucket found for row: %s", inputRow);
+        throw new ISE("No bucket found for row: %s", inputRow);
       }
 
       final long truncatedTimestamp = granularitySpec.getQueryGranularity()

indexing-service/src/main/java/org/apache/druid/indexing/common/task/AppenderatorDriverRealtimeIndexTask.java

@@ -68,6 +68,7 @@ import org.apache.druid.java.util.emitter.EmittingLogger;
 import org.apache.druid.query.NoopQueryRunner;
 import org.apache.druid.query.Query;
 import org.apache.druid.query.QueryRunner;
+import org.apache.druid.segment.SegmentUtils;
 import org.apache.druid.segment.indexing.DataSchema;
 import org.apache.druid.segment.indexing.RealtimeIOConfig;
 import org.apache.druid.segment.realtime.FireDepartment;
@@ -318,7 +319,10 @@ public class AppenderatorDriverRealtimeIndexTask extends AbstractTask implements
 
       final TransactionalSegmentPublisher publisher = (mustBeNullOrEmptySegments, segments, commitMetadata) -> {
         if (mustBeNullOrEmptySegments != null && !mustBeNullOrEmptySegments.isEmpty()) {
-          throw new ISE("WTH? stream ingestion tasks are overwriting segments[%s]", mustBeNullOrEmptySegments);
+          throw new ISE(
+              "Stream ingestion task unexpectedly attempted to overwrite segments: %s",
+              SegmentUtils.commaSeparatedIdentifiers(mustBeNullOrEmptySegments)
+          );
         }
         final SegmentTransactionalInsertAction action = SegmentTransactionalInsertAction.appendAction(
             segments,

indexing-service/src/main/java/org/apache/druid/indexing/common/task/ArchiveTask.java

@@ -73,7 +73,7 @@ public class ArchiveTask extends AbstractFixedIntervalTask
     for (final DataSegment unusedSegment : unusedSegments) {
       if (unusedSegment.getVersion().compareTo(myLock.getVersion()) > 0) {
         throw new ISE(
-            "WTF?! Unused segment[%s] has version[%s] > task version[%s]",
+            "Unused segment[%s] has version[%s] > task version[%s]",
             unusedSegment.getId(),
             unusedSegment.getVersion(),
             myLock.getVersion()

indexing-service/src/main/java/org/apache/druid/indexing/common/task/MoveTask.java

@@ -81,7 +81,7 @@ public class MoveTask extends AbstractFixedIntervalTask
     for (final DataSegment unusedSegment : unusedSegments) {
       if (unusedSegment.getVersion().compareTo(myLock.getVersion()) > 0) {
         throw new ISE(
-            "WTF?! Unused segment[%s] has version[%s] > task version[%s]",
+            "Unused segment[%s] has version[%s] > task version[%s]",
             unusedSegment.getId(),
             unusedSegment.getVersion(),
             myLock.getVersion()

indexing-service/src/main/java/org/apache/druid/indexing/common/task/RealtimeIndexTask.java

@@ -212,7 +212,7 @@ public class RealtimeIndexTask extends AbstractTask
     runThread = Thread.currentThread();
 
     if (this.plumber != null) {
-      throw new IllegalStateException("WTF?!? run with non-null plumber??!");
+      throw new IllegalStateException("Plumber must be null");
     }
 
     setupTimeoutAlert();

indexing-service/src/main/java/org/apache/druid/indexing/common/task/RestoreTask.java

@@ -74,7 +74,7 @@ public class RestoreTask extends AbstractFixedIntervalTask
     for (final DataSegment unusedSegment : unusedSegments) {
       if (unusedSegment.getVersion().compareTo(myLock.getVersion()) > 0) {
         throw new ISE(
-            "WTF?! Unused segment[%s] has version[%s] > task version[%s]",
+            "Unused segment[%s] has version[%s] > task version[%s]",
             unusedSegment.getId(),
             unusedSegment.getVersion(),
             myLock.getVersion()

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/PartialSegmentMergeTask.java

@@ -146,7 +146,7 @@ abstract class PartialSegmentMergeTask<S extends ShardSpec, P extends PartitionL
       final String mustBeNull = intervalToVersion.put(lock.getInterval(), lock.getVersion());
       if (mustBeNull != null) {
         throw new ISE(
-            "WTH? Two versions([%s], [%s]) for the same interval[%s]?",
+            "Unexpected state: Two versions([%s], [%s]) for the same interval[%s]",
             lock.getVersion(),
             mustBeNull,
             lock.getInterval()

indexing-service/src/main/java/org/apache/druid/indexing/overlord/BaseRestorableTaskRunner.java

@@ -95,7 +95,7 @@ public abstract class BaseRestorableTaskRunner<WorkItemType extends TaskRunnerWo
         final Task task = jsonMapper.readValue(taskFile, Task.class);
 
         if (!task.getId().equals(taskId)) {
-          throw new ISE("WTF?! Task[%s] restore file had wrong id[%s].", taskId, task.getId());
+          throw new ISE("Task[%s] restore file had wrong id[%s]", taskId, task.getId());
         }
 
         if (taskConfig.isRestoreTasksOnRestart() && task.canRestore()) {

indexing-service/src/main/java/org/apache/druid/indexing/overlord/ForkingTaskRunner.java

@@ -174,7 +174,7 @@ public class ForkingTaskRunner
                         final ForkingTaskRunnerWorkItem taskWorkItem = tasks.get(task.getId());
 
                         if (taskWorkItem == null) {
-                          LOGGER.makeAlert("WTF?! TaskInfo disappeared!").addData("task", task.getId()).emit();
+                          LOGGER.makeAlert("TaskInfo disappeared!").addData("task", task.getId()).emit();
                           throw new ISE("TaskInfo disappeared for task[%s]!", task.getId());
                         }
 
@@ -183,7 +183,7 @@ public class ForkingTaskRunner
                         }
 
                         if (taskWorkItem.processHolder != null) {
-                          LOGGER.makeAlert("WTF?! TaskInfo already has a processHolder")
+                          LOGGER.makeAlert("TaskInfo already has a processHolder")
                                 .addData("task", task.getId())
                                 .emit();
                           throw new ISE("TaskInfo already has processHolder for task[%s]!", task.getId());

indexing-service/src/main/java/org/apache/druid/indexing/overlord/RemoteTaskRunner.java

@@ -770,7 +770,7 @@ public class RemoteTaskRunner implements WorkerTaskRunner, TaskLogStreamer
     final RemoteTaskRunnerWorkItem removed = completeTasks.remove(taskId);
     final Worker worker;
     if (removed == null || (worker = removed.getWorker()) == null) {
-      log.makeAlert("WTF?! Asked to cleanup nonexistent task")
+      log.makeAlert("Asked to cleanup nonexistent task")
          .addData("taskId", taskId)
          .emit();
     } else {
@@ -901,7 +901,7 @@ public class RemoteTaskRunner implements WorkerTaskRunner, TaskLogStreamer
 
       RemoteTaskRunnerWorkItem workItem = pendingTasks.remove(task.getId());
       if (workItem == null) {
-        log.makeAlert("WTF?! Got a null work item from pending tasks?! How can this be?!")
+        log.makeAlert("Ignoring null work item from pending task queue")
            .addData("taskId", task.getId())
            .emit();
         return false;
@@ -1119,7 +1119,7 @@ public class RemoteTaskRunner implements WorkerTaskRunner, TaskLogStreamer
       zkWorker.setWorker(worker);
     } else {
       log.warn(
-          "WTF, worker[%s] updated its announcement but we didn't have a ZkWorker for it. Ignoring.",
+          "Worker[%s] updated its announcement but we didn't have a ZkWorker for it. Ignoring.",
           worker.getHost()
       );
     }

indexing-service/src/main/java/org/apache/druid/indexing/overlord/SingleTaskBackgroundRunner.java

@@ -171,7 +171,7 @@ public class SingleTaskBackgroundRunner implements TaskRunner, QuerySegmentWalke
         executorService.shutdown();
       }
       catch (SecurityException ex) {
-        log.wtf(ex, "I can't control my own threads!");
+        log.error(ex, "I can't control my own threads!");
       }
     }
 
@@ -233,7 +233,7 @@ public class SingleTaskBackgroundRunner implements TaskRunner, QuerySegmentWalke
         executorService.shutdownNow();
       }
       catch (SecurityException ex) {
-        log.wtf(ex, "I can't control my own threads!");
+        log.error(ex, "I can't control my own threads!");
       }
     }
   }

indexing-service/src/main/java/org/apache/druid/indexing/overlord/TaskLockbox.java

@@ -146,7 +146,7 @@ public class TaskLockbox
         final TaskLock savedTaskLock = Preconditions.checkNotNull(taskAndLock.rhs, "savedTaskLock");
         if (savedTaskLock.getInterval().toDurationMillis() <= 0) {
           // "Impossible", but you never know what crazy stuff can be restored from storage.
-          log.warn("WTF?! Got lock[%s] with empty interval for task: %s", savedTaskLock, task.getId());
+          log.warn("Ignoring lock[%s] with empty interval for task: %s", savedTaskLock, task.getId());
           continue;
         }
 

indexing-service/src/main/java/org/apache/druid/indexing/overlord/ThreadingTaskRunner.java

@@ -176,7 +176,7 @@ public class ThreadingTaskRunner
                               taskWorkItem = tasks.get(task.getId());
 
                               if (taskWorkItem == null) {
-                                LOGGER.makeAlert("WTF?! TaskInfo disappeared!").addData("task", task.getId()).emit();
+                                LOGGER.makeAlert("TaskInfo disappeared").addData("task", task.getId()).emit();
                                 throw new ISE("TaskInfo disappeared for task[%s]!", task.getId());
                               }
 

indexing-service/src/main/java/org/apache/druid/indexing/overlord/hrtr/HttpRemoteTaskRunner.java

@@ -487,7 +487,7 @@ public class HttpRemoteTaskRunner implements WorkerTaskRunner, TaskLogStreamer
     long workerDiscoveryStartTime = System.currentTimeMillis();
     while (!workerViewInitialized.await(30, TimeUnit.SECONDS)) {
       if (System.currentTimeMillis() - workerDiscoveryStartTime > TimeUnit.MINUTES.toMillis(5)) {
-        throw new ISE("WTF! Couldn't discover workers.");
+        throw new ISE("Couldn't discover workers.");
       } else {
         log.info("Waiting for worker discovery...");
       }
@@ -1169,7 +1169,7 @@ public class HttpRemoteTaskRunner implements WorkerTaskRunner, TaskLogStreamer
         }
 
         if (immutableWorker == null) {
-          throw new ISE("WTH! NULL immutableWorker");
+          throw new ISE("Unexpected state: null immutableWorker");
         }
 
         try {
@@ -1405,7 +1405,7 @@ public class HttpRemoteTaskRunner implements WorkerTaskRunner, TaskLogStreamer
               break;
             default:
               log.makeAlert(
-                  "WTF! Found unrecognized state[%s] of task[%s] in taskStorage. Notification[%s] from worker[%s] is ignored.",
+                  "Found unrecognized state[%s] of task[%s] in taskStorage. Notification[%s] from worker[%s] is ignored.",
                   knownStatusInStorage.get().getStatusCode(),
                   taskId,
                   announcement,
@@ -1468,7 +1468,7 @@ public class HttpRemoteTaskRunner implements WorkerTaskRunner, TaskLogStreamer
                 break;
               default:
                 log.makeAlert(
-                    "WTF! Found unrecognized state[%s] of task[%s]. Notification[%s] from worker[%s] is ignored.",
+                    "Found unrecognized state[%s] of task[%s]. Notification[%s] from worker[%s] is ignored.",
                     taskItem.getState(),
                     taskId,
                     announcement,
@@ -1513,7 +1513,7 @@ public class HttpRemoteTaskRunner implements WorkerTaskRunner, TaskLogStreamer
                 break;
               default:
                 log.makeAlert(
-                    "WTF! Found unrecognized state[%s] of task[%s]. Notification[%s] from worker[%s] is ignored.",
+                    "Found unrecognized state[%s] of task[%s]. Notification[%s] from worker[%s] is ignored.",
                     taskItem.getState(),
                     taskId,
                     announcement,
@@ -1523,7 +1523,7 @@ public class HttpRemoteTaskRunner implements WorkerTaskRunner, TaskLogStreamer
             break;
           default:
             log.makeAlert(
-                "WTF! Worker[%s] reported unrecognized state[%s] for task[%s].",
+                "Worker[%s] reported unrecognized state[%s] for task[%s].",
                 worker.getHost(),
                 announcement.getTaskStatus().getStatusCode(),
                 taskId

indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/SeekableStreamIndexTaskRunner.java

@@ -470,7 +470,7 @@ public abstract class SeekableStreamIndexTaskRunner<PartitionIdType, SequenceOff
         // Sanity checks.
         if (!restoredNextPartitions.getStream().equals(ioConfig.getStartSequenceNumbers().getStream())) {
           throw new ISE(
-              "WTF?! Restored stream[%s] but expected stream[%s]",
+              "Restored stream[%s] but expected stream[%s]",
               restoredNextPartitions.getStream(),
               ioConfig.getStartSequenceNumbers().getStream()
           );
@@ -478,7 +478,7 @@ public abstract class SeekableStreamIndexTaskRunner<PartitionIdType, SequenceOff
 
         if (!currOffsets.keySet().equals(ioConfig.getStartSequenceNumbers().getPartitionSequenceNumberMap().keySet())) {
           throw new ISE(
-              "WTF?! Restored partitions[%s] but expected partitions[%s]",
+              "Restored partitions[%s] but expected partitions[%s]",
               currOffsets.keySet(),
               ioConfig.getStartSequenceNumbers().getPartitionSequenceNumberMap().keySet()
           );
@@ -633,7 +633,7 @@ public abstract class SeekableStreamIndexTaskRunner<PartitionIdType, SequenceOff
 
                 if (sequenceToUse == null) {
                   throw new ISE(
-                      "WTH?! cannot find any valid sequence for record with partition [%s] and sequenceNumber [%s]. Current sequences: %s",
+                      "Cannot find any valid sequence for record with partition [%s] and sequenceNumber [%s]. Current sequences: %s",
                       record.getPartitionId(),
                       record.getSequenceNumber(),
                       sequences
@@ -1616,7 +1616,7 @@ public abstract class SeekableStreamIndexTaskRunner<PartitionIdType, SequenceOff
         pauseLock.lockInterruptibly();
         // Perform all sequence related checks before checking for isPaused()
         // and after acquiring pauseLock to correctly guard against duplicate requests
-        Preconditions.checkState(sequenceNumbers.size() > 0, "WTH?! No Sequences found to set end sequences");
+        Preconditions.checkState(sequenceNumbers.size() > 0, "No sequences found to set end sequences");
 
         final SequenceMetadata<PartitionIdType, SequenceOffsetType> latestSequence = getLastSequenceMetadata();
         final Set<PartitionIdType> exclusiveStartPartitions;
@@ -1641,7 +1641,7 @@ public abstract class SeekableStreamIndexTaskRunner<PartitionIdType, SequenceOff
         } else if (latestSequence.isCheckpointed()) {
           return Response.status(Response.Status.BAD_REQUEST)
                          .entity(StringUtils.format(
-                             "WTH?! Sequence [%s] has already endOffsets set, cannot set to [%s]",
+                             "Sequence [%s] has already endOffsets set, cannot set to [%s]",
                              latestSequence,
                              sequenceNumbers
                          )).build();

indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/SequenceMetadata.java

@@ -32,6 +32,7 @@ import org.apache.druid.indexing.seekablestream.common.OrderedPartitionableRecor
 import org.apache.druid.indexing.seekablestream.common.OrderedSequenceNumber;
 import org.apache.druid.java.util.common.ISE;
 import org.apache.druid.java.util.emitter.EmittingLogger;
+import org.apache.druid.segment.SegmentUtils;
 import org.apache.druid.segment.realtime.appenderator.TransactionalSegmentPublisher;
 import org.apache.druid.timeline.DataSegment;
 
@@ -341,7 +342,10 @@ public class SequenceMetadata<PartitionIdType, SequenceOffsetType>
     ) throws IOException
     {
       if (mustBeNullOrEmptySegments != null && !mustBeNullOrEmptySegments.isEmpty()) {
-        throw new ISE("WTH? stream ingestion tasks are overwriting segments[%s]", mustBeNullOrEmptySegments);
+        throw new ISE(
+            "Stream ingestion task unexpectedly attempted to overwrite segments: %s",
+            SegmentUtils.commaSeparatedIdentifiers(mustBeNullOrEmptySegments)
+        );
       }
       final Map commitMetaMap = (Map) Preconditions.checkNotNull(commitMetadata, "commitMetadata");
       final SeekableStreamEndSequenceNumbers<PartitionIdType, SequenceOffsetType> finalPartitions =
@@ -353,7 +357,7 @@ public class SequenceMetadata<PartitionIdType, SequenceOffsetType>
       // Sanity check, we should only be publishing things that match our desired end state.
       if (!getEndOffsets().equals(finalPartitions.getPartitionSequenceNumberMap())) {
         throw new ISE(
-            "WTF?! Driver for sequence [%s], attempted to publish invalid metadata[%s].",
+            "Driver for sequence[%s] attempted to publish invalid metadata[%s].",
             SequenceMetadata.this.toString(),
             commitMetadata
         );

indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/SeekableStreamSupervisor.java

@@ -423,7 +423,7 @@ public abstract class SeekableStreamSupervisor<PartitionIdType, SequenceOffsetTy
           log.warn("Ignoring checkpoint request because taskGroup[%d] is inactive", taskGroupId);
           return false;
         } else {
-          throw new ISE("WTH?! cannot find taskGroup [%s] among all activelyReadingTaskGroups [%s]", taskGroupId,
+          throw new ISE("Cannot find taskGroup [%s] among all activelyReadingTaskGroups [%s]", taskGroupId,
                         activelyReadingTaskGroups
           );
         }
@@ -1494,7 +1494,7 @@ public abstract class SeekableStreamSupervisor<PartitionIdType, SequenceOffsetTy
                             final TaskData prevTaskData = taskGroup.tasks.putIfAbsent(taskId, new TaskData());
                             if (prevTaskData != null) {
                               throw new ISE(
-                                  "WTH? a taskGroup[%s] already exists for new task[%s]",
+                                  "taskGroup[%s] already exists for new task[%s]",
                                   prevTaskData,
                                   taskId
                               );
@@ -2518,7 +2518,7 @@ public abstract class SeekableStreamSupervisor<PartitionIdType, SequenceOffsetTy
                   // The below get should throw ExecutionException since result is null.
                   final Map<PartitionIdType, SequenceOffsetType> pauseResult = pauseFutures.get(i).get();
                   throw new ISE(
-                      "WTH? The pause request for task [%s] is supposed to fail, but returned [%s]",
+                      "Pause request for task [%s] should have failed, but returned [%s]",
                       taskId,
                       pauseResult
                   );
@@ -2674,7 +2674,7 @@ public abstract class SeekableStreamSupervisor<PartitionIdType, SequenceOffsetTy
           final String taskId = entry.getKey();
           final TaskData taskData = entry.getValue();
 
-          Preconditions.checkNotNull(taskData.status, "WTH? task[%s] has a null status", taskId);
+          Preconditions.checkNotNull(taskData.status, "task[%s] has null status", taskId);
 
           if (taskData.status.isFailure()) {
             stateManager.recordCompletedTaskState(TaskState.FAILED);
@@ -2774,7 +2774,7 @@ public abstract class SeekableStreamSupervisor<PartitionIdType, SequenceOffsetTy
           continue;
         }
 
-        Preconditions.checkNotNull(taskData.status, "WTH? task[%s] has a null status", taskId);
+        Preconditions.checkNotNull(taskData.status, "Task[%s] has null status", taskId);
 
         // remove failed tasks
         if (taskData.status.isFailure()) {

indexing-service/src/main/java/org/apache/druid/indexing/worker/WorkerTaskManager.java

@@ -345,7 +345,7 @@ public abstract class WorkerTaskManager
         if (taskId.equals(task.getId())) {
           assignedTasks.put(taskId, task);
         } else {
-          throw new ISE("WTF! Corrupted assigned task on disk[%s].", taskFile.getAbsoluteFile());
+          throw new ISE("Corrupted assigned task on disk[%s].", taskFile.getAbsoluteFile());
         }
       }
       catch (IOException ex) {
@@ -471,7 +471,7 @@ public abstract class WorkerTaskManager
         if (taskId.equals(taskAnnouncement.getTaskId())) {
           completedTasks.put(taskId, taskAnnouncement);
         } else {
-          throw new ISE("WTF! Corrupted completed task on disk[%s].", taskFile.getAbsoluteFile());
+          throw new ISE("Corrupted completed task on disk[%s].", taskFile.getAbsoluteFile());
         }
       }
       catch (IOException ex) {
@@ -699,7 +699,7 @@ public abstract class WorkerTaskManager
 
         if (!status.isComplete()) {
           log.warn(
-              "WTF?! Got status notice for task [%s] that isn't complete (status = [%s])...",
+              "Got status notice for task [%s] that isn't complete (status = [%s])...",
               task.getId(),
               status.getStatusCode()
           );

indexing-service/src/test/java/org/apache/druid/indexing/firehose/IngestSegmentFirehoseFactoryTimelineTest.java

@@ -331,7 +331,7 @@ public class IngestSegmentFirehoseFactoryTimelineTest
           if (intervals.equals(ImmutableList.of(testCase.interval))) {
             return ImmutableSet.copyOf(testCase.segments);
           } else {
-            throw new IllegalArgumentException("WTF");
+            throw new IllegalArgumentException("BAD");
           }
         }
 

processing/src/main/java/org/apache/druid/guice/PropertiesModule.java

@@ -76,7 +76,7 @@ public class PropertiesModule implements Module
         }
       }
       catch (FileNotFoundException e) {
-        log.wtf(e, "This can only happen if the .exists() call lied.");
+        log.error(e, "This can only happen if the .exists() call lied.");
       }
       finally {
         CloseQuietly.close(stream);

processing/src/main/java/org/apache/druid/query/ChainedExecutionQueryRunner.java

@@ -124,7 +124,7 @@ public class ChainedExecutionQueryRunner<T> implements QueryRunner<T>
 
                                     List<T> retVal = result.toList();
                                     if (retVal == null) {
-                                      throw new ISE("Got a null list of results! WTF?!");
+                                      throw new ISE("Got a null list of results");
                                     }
 
                                     return retVal;

processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/ByteBufferHashTable.java

@@ -169,7 +169,7 @@ public class ByteBufferHashTable
     }
 
     if (newBuckets < maxBuckets) {
-      throw new ISE("WTF?! newBuckets[%,d] < maxBuckets[%,d]", newBuckets, maxBuckets);
+      throw new ISE("newBuckets[%,d] < maxBuckets[%,d]", newBuckets, maxBuckets);
     }
 
     ByteBuffer newTableBuffer = buffer.duplicate();
@@ -206,7 +206,7 @@ public class ByteBufferHashTable
         final int newBucket = findBucket(true, newBuckets, newTableBuffer, keyBuffer, keyHash);
 
         if (newBucket < 0) {
-          throw new ISE("WTF?! Couldn't find a bucket while resizing?!");
+          throw new ISE("Couldn't find a bucket while resizing");
         }
 
         final int newBucketOffset = newBucket * bucketSizeWithHash;
@@ -230,7 +230,7 @@ public class ByteBufferHashTable
     growthCount++;
 
     if (size != newSize) {
-      throw new ISE("WTF?! size[%,d] != newSize[%,d] after resizing?!", size, newSize);
+      throw new ISE("size[%,d] != newSize[%,d] after resizing", size, newSize);
     }
   }
 

processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/LimitedBufferHashGrouper.java

@@ -98,7 +98,7 @@ public class LimitedBufferHashGrouper<KeyType> extends AbstractBufferHashGrouper
     // We check this already in SpillingGrouper to ensure that LimitedBufferHashGrouper is only used when there is
     // sufficient buffer capacity. If this error occurs, something went very wrong.
     if (!validateBufferCapacity(totalBuffer.capacity())) {
-      throw new IAE("WTF? Using LimitedBufferHashGrouper with insufficient buffer capacity.");
+      throw new IAE("LimitedBufferHashGrouper initialized with insufficient buffer capacity");
     }
 
     //only store offsets up to `limit` + 1 instead of up to # of buckets, we only keep the top results
@@ -485,7 +485,7 @@ public class LimitedBufferHashGrouper<KeyType> extends AbstractBufferHashGrouper
           final int newBucket = findBucket(true, maxBuckets, newTableBuffer, keyBuffer, keyHash);
 
           if (newBucket < 0) {
-            throw new ISE("WTF?! Couldn't find a bucket while resizing?!");
+            throw new ISE("Couldn't find a bucket while resizing");
           }
 
           final int newBucketOffset = newBucket * bucketSizeWithHash;

processing/src/main/java/org/apache/druid/query/scan/ScanQueryEngine.java

@@ -65,7 +65,7 @@ public class ScanQueryEngine
   )
   {
     // "legacy" should be non-null due to toolChest.mergeResults
-    final boolean legacy = Preconditions.checkNotNull(query.isLegacy(), "WTF?! Expected non-null legacy");
+    final boolean legacy = Preconditions.checkNotNull(query.isLegacy(), "Expected non-null 'legacy' parameter");
 
     final Object numScannedRows = responseContext.get(ResponseContext.Key.NUM_SCANNED_ROWS);
     if (numScannedRows != null) {

processing/src/main/java/org/apache/druid/query/scan/ScanQueryRunnerFactory.java

@@ -253,7 +253,7 @@ public class ScanQueryRunnerFactory implements QueryRunnerFactory<ScanResultValu
               }
             }
             if (finalInterval == null) {
-              throw new ISE("Row unexpectedly came from an unscanned interval");
+              throw new ISE("Row came from an unscanned interval");
             }
           }
         }

processing/src/main/java/org/apache/druid/query/topn/AggregateTopNMetricFirstAlgorithm.java

@@ -80,7 +80,7 @@ public class AggregateTopNMetricFirstAlgorithm implements TopNAlgorithm<int[], T
         AggregatorUtil.condensedAggregators(query.getAggregatorSpecs(), query.getPostAggregatorSpecs(), metric);
 
     if (condensedAggPostAggPair.lhs.isEmpty() && condensedAggPostAggPair.rhs.isEmpty()) {
-      throw new ISE("WTF! Can't find the metric to do topN over?");
+      throw new ISE("Can't find the topN metric");
     }
     // Run topN for only a single metric
     TopNQuery singleMetricQuery = new TopNQueryBuilder(query)

processing/src/main/java/org/apache/druid/segment/incremental/OffheapIncrementalIndex.java

@@ -217,7 +217,7 @@ public class OffheapIncrementalIndex extends IncrementalIndex<BufferAggregator>
         if (IncrementalIndexRow.EMPTY_ROW_INDEX == prev) {
           getNumEntries().incrementAndGet();
         } else {
-          throw new ISE("WTF! we are in sychronized block.");
+          throw new ISE("Unexpected state: Concurrent fact addition.");
         }
       }
     }

processing/src/main/java/org/apache/druid/segment/virtual/SingleLongInputCachingExpressionColumnValueSelector.java

@@ -60,7 +60,7 @@ public class SingleLongInputCachingExpressionColumnValueSelector implements Colu
   {
     // Verify expression has just one binding.
     if (expression.analyzeInputs().getRequiredBindings().size() != 1) {
-      throw new ISE("WTF?! Expected expression with just one binding");
+      throw new ISE("Expected expression with just one binding");
     }
 
     this.selector = Preconditions.checkNotNull(selector, "selector");

processing/src/main/java/org/apache/druid/segment/virtual/SingleStringInputCachingExpressionColumnValueSelector.java

@@ -56,7 +56,7 @@ public class SingleStringInputCachingExpressionColumnValueSelector implements Co
   {
     // Verify expression has just one binding.
     if (expression.analyzeInputs().getRequiredBindings().size() != 1) {
-      throw new ISE("WTF?! Expected expression with just one binding");
+      throw new ISE("Expected expression with just one binding");
     }
 
     this.selector = Preconditions.checkNotNull(selector, "selector");

processing/src/test/java/org/apache/druid/query/SchemaEvolutionTest.java

@@ -210,7 +210,7 @@ public class SchemaEvolutionTest
 
     if (index4.getAvailableDimensions().size() != 0) {
       // Just double-checking that the exclusions are working properly
-      throw new ISE("WTF?! Expected no dimensions in index4");
+      throw new ISE("Expected no dimensions in index4");
     }
   }
 

processing/src/test/java/org/apache/druid/query/groupby/epinephelinae/LimitedBufferHashGrouperTest.java

@@ -132,7 +132,7 @@ public class LimitedBufferHashGrouperTest
   public void testBufferTooSmall()
   {
     expectedException.expect(IAE.class);
-    expectedException.expectMessage("WTF? Using LimitedBufferHashGrouper with insufficient buffer capacity.");
+    expectedException.expectMessage("LimitedBufferHashGrouper initialized with insufficient buffer capacity");
     final TestColumnSelectorFactory columnSelectorFactory = GrouperTestUtil.newColumnSelectorFactory();
     makeGrouper(columnSelectorFactory, 10, 2, 100);
   }

server/src/main/java/org/apache/druid/curator/discovery/ServerDiscoverySelector.java

@@ -60,7 +60,7 @@ public class ServerDiscoverySelector implements DiscoverySelector<Server>
     {
       Preconditions.checkState(
           instance.getPort() >= 0 || (instance.getSslPort() != null && instance.getSslPort() >= 0),
-          "WTH?! Both port and sslPort not set"
+          "Both port and sslPort not set"
       );
       final int port;
       final String scheme;

server/src/main/java/org/apache/druid/metadata/IndexerSQLMetadataStorageCoordinator.java

@@ -322,7 +322,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
 
     // Metadata transaction cannot fail because we are not trying to do one.
     if (!result.isSuccess()) {
-      throw new ISE("WTF?! announceHistoricalSegments failed with null metadata, should not happen.");
+      throw new ISE("announceHistoricalSegments failed with null metadata, should not happen.");
     }
 
     return result.getSegments();

server/src/main/java/org/apache/druid/segment/loading/SegmentLoaderLocalCacheManager.java

@@ -334,9 +334,9 @@ public class SegmentLoaderLocalCacheManager implements SegmentLoader
         dataSegment,
         (segment, existingLock) -> {
           if (existingLock == null) {
-            throw new ISE("WTH? the given lock has already been removed");
+            throw new ISE("Lock has already been removed");
           } else if (existingLock != lock) {
-            throw new ISE("WTH? Different lock instance");
+            throw new ISE("Different lock instance");
           } else {
             if (existingLock.numReferences == 1) {
               return null;

server/src/main/java/org/apache/druid/segment/realtime/FireHydrant.java

@@ -96,7 +96,7 @@ public class FireHydrant
           !newSegment.getId().equals(currentSegment.getId())) {
         // Sanity check: identifier should not change
         throw new ISE(
-            "WTF?! Cannot swap identifier[%s] -> [%s]!",
+            "Cannot swap identifier[%s] -> [%s]",
             currentSegment.getId(),
             newSegment.getId()
         );

server/src/main/java/org/apache/druid/segment/realtime/appenderator/AppenderatorImpl.java

@@ -706,12 +706,12 @@ public class AppenderatorImpl implements Appenderator
     // Sanity checks
     for (FireHydrant hydrant : sink) {
       if (sink.isWritable()) {
-        throw new ISE("WTF?! Expected sink to be no longer writable before mergeAndPush. Segment[%s].", identifier);
+        throw new ISE("Expected sink to be no longer writable before mergeAndPush for segment[%s].", identifier);
       }
 
       synchronized (hydrant) {
         if (!hydrant.hasSwapped()) {
-          throw new ISE("WTF?! Expected sink to be fully persisted before mergeAndPush. Segment[%s].", identifier);
+          throw new ISE("Expected sink to be fully persisted before mergeAndPush for segment[%s].", identifier);
         }
       }
     }

server/src/main/java/org/apache/druid/segment/realtime/appenderator/BaseAppenderatorDriver.java

@@ -131,7 +131,7 @@ public abstract class BaseAppenderatorDriver implements Closeable
       // There should be only one appending segment at any time
       Preconditions.checkState(
           this.appendingSegment == null,
-          "WTF?! Current appendingSegment[%s] is not null. "
+          "Current appendingSegment[%s] is not null. "
           + "Its state must be changed before setting a new appendingSegment[%s]",
           this.appendingSegment,
           appendingSegment
@@ -345,7 +345,7 @@ public abstract class BaseAppenderatorDriver implements Closeable
           for (SegmentIdWithShardSpec identifier : appenderator.getSegments()) {
             if (identifier.equals(newSegment)) {
               throw new ISE(
-                  "WTF?! Allocated segment[%s] which conflicts with existing segment[%s].",
+                  "Allocated segment[%s] which conflicts with existing segment[%s].",
                   newSegment,
                   identifier
               );
@@ -418,7 +418,7 @@ public abstract class BaseAppenderatorDriver implements Closeable
         );
       }
       catch (SegmentNotWritableException e) {
-        throw new ISE(e, "WTF?! Segment[%s] not writable when it should have been.", identifier);
+        throw new ISE(e, "Segment[%s] not writable when it should have been.", identifier);
       }
     } else {
       return AppenderatorDriverAddResult.fail();

server/src/main/java/org/apache/druid/segment/realtime/appenderator/StreamAppenderatorDriver.java

@@ -197,7 +197,7 @@ public class StreamAppenderatorDriver extends BaseAppenderatorDriver
     synchronized (segments) {
       final SegmentsForSequence activeSegmentsForSequence = segments.get(sequenceName);
       if (activeSegmentsForSequence == null) {
-        throw new ISE("WTF?! Asked to remove segments for sequenceName[%s] which doesn't exist...", sequenceName);
+        throw new ISE("Asked to remove segments for sequenceName[%s], which doesn't exist", sequenceName);
       }
 
       for (final SegmentIdWithShardSpec identifier : identifiers) {
@@ -207,7 +207,7 @@ public class StreamAppenderatorDriver extends BaseAppenderatorDriver
         if (segmentsOfInterval == null ||
             segmentsOfInterval.getAppendingSegment() == null ||
             !segmentsOfInterval.getAppendingSegment().getSegmentIdentifier().equals(identifier)) {
-          throw new ISE("WTF?! Asked to remove segment[%s] that didn't exist...", identifier);
+          throw new ISE("Asked to remove segment[%s], which doesn't exist", identifier);
         }
         segmentsOfInterval.finishAppendingToCurrentActiveSegment(SegmentWithState::finishAppending);
       }
@@ -424,7 +424,7 @@ public class StreamAppenderatorDriver extends BaseAppenderatorDriver
       if (segmentWithState.getState() == SegmentState.APPENDING) {
         if (pair != null && pair.lhs != null) {
           throw new ISE(
-              "WTF?! there was already an appendingSegment[%s] before adding an appendingSegment[%s]",
+              "appendingSegment[%s] existed before adding an appendingSegment[%s]",
               pair.lhs,
               segmentWithState
           );

server/src/main/java/org/apache/druid/segment/realtime/plumber/Plumbers.java

@@ -76,7 +76,7 @@ public class Plumbers
     catch (IndexSizeExceededException e) {
       // Shouldn't happen if this is only being called by a single thread.
       // plumber.add should be swapping out indexes before they fill up.
-      throw new ISE(e, "WTF?! Index size exceeded, this shouldn't happen. Bad Plumber!");
+      throw new ISE(e, "Index size exceeded");
     }
 
     if (addResult.getRowCount() == -1) {

server/src/main/java/org/apache/druid/segment/realtime/plumber/RealtimePlumber.java

@@ -95,6 +95,7 @@ import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
 /**
+ *
  */
 public class RealtimePlumber implements Plumber
 {
@@ -213,7 +214,8 @@ public class RealtimePlumber implements Plumber
   }
 
   @Override
-  public IncrementalIndexAddResult add(InputRow row, Supplier<Committer> committerSupplier) throws IndexSizeExceededException
+  public IncrementalIndexAddResult add(InputRow row, Supplier<Committer> committerSupplier)
+      throws IndexSizeExceededException
   {
     long messageTimestamp = row.getTimestampFromEpoch();
     final Sink sink = getSink(messageTimestamp);
@@ -394,7 +396,7 @@ public class RealtimePlumber implements Plumber
               if (!isPushedMarker.exists()) {
                 removeSegment(sink, mergedTarget);
                 if (mergedTarget.exists()) {
-                  log.wtf("Merged target[%s] exists?!", mergedTarget);
+                  log.warn("Merged target[%s] still exists after attempt to delete it; skipping push.", mergedTarget);
                   return;
                 }
               } else {

server/src/main/java/org/apache/druid/server/coordination/ChangeRequestHttpSyncer.java

@@ -391,7 +391,7 @@ public class ChangeRequestHttpSyncer<T>
         } else {
           log.makeAlert(
               th,
-              "WTF! Couldn't schedule next sync. [%s] is not being synced any more, restarting Druid process on that "
+              "Couldn't schedule next sync. [%s] is not being synced any more, restarting Druid process on that "
               + "server might fix the issue.",
               logIdentity
           ).emit();

server/src/main/java/org/apache/druid/server/coordinator/HttpLoadQueuePeon.java

@@ -227,7 +227,7 @@ public class HttpLoadQueuePeon extends LoadQueuePeon
                             break;
                           default:
                             scheduleNextRunImmediately = false;
-                            log.error("WTF! Server[%s] returned unknown state in status[%s].", serverId, e.getStatus());
+                            log.error("Server[%s] returned unknown state in status[%s].", serverId, e.getStatus());
                         }
                       }
                     }

server/src/main/java/org/apache/druid/server/coordinator/duty/CompactSegments.java

@@ -98,7 +98,7 @@ public class CompactSegments implements CoordinatorDuty
         for (TaskStatusPlus status : compactionTasks) {
           final TaskPayloadResponse response = indexingServiceClient.getTaskPayload(status.getId());
           if (response == null) {
-            throw new ISE("WTH? got a null paylord from overlord for task[%s]", status.getId());
+            throw new ISE("Got a null paylord from overlord for task[%s]", status.getId());
           }
           if (COMPACTION_TASK_TYPE.equals(response.getPayload().getType())) {
             final ClientCompactionTaskQuery compactionTaskQuery = (ClientCompactionTaskQuery) response.getPayload();
@@ -107,7 +107,7 @@ public class CompactSegments implements CoordinatorDuty
             final int numSubTasks = findNumMaxConcurrentSubTasks(compactionTaskQuery.getTuningConfig());
             numEstimatedNonCompleteCompactionTasks += numSubTasks + 1; // count the compaction task itself
           } else {
-            throw new ISE("WTH? task[%s] is not a compactionTask?", status.getId());
+            throw new ISE("task[%s] is not a compactionTask", status.getId());
           }
         }
 

server/src/main/java/org/apache/druid/server/lookup/cache/LookupCoordinatorManager.java

@@ -395,7 +395,7 @@ public class LookupCoordinatorManager
                 lookupCoordinatorManagerConfig.getHostTimeout().getMillis() * 10,
                 TimeUnit.MILLISECONDS
             )) {
-          throw new ISE("WTF! LookupCoordinatorManager executor from last start() hasn't finished. Failed to Start.");
+          throw new ISE("LookupCoordinatorManager executor from last start() hasn't finished. Failed to Start.");
         }
 
         executorService = MoreExecutors.listeningDecorator(

server/src/test/java/org/apache/druid/segment/realtime/appenderator/AppenderatorTest.java

@@ -844,7 +844,7 @@ public class AppenderatorTest extends InitializedNullHandlingTest
           } else if (a instanceof DataSegment && b instanceof DataSegment) {
             return ((DataSegment) a).getId().compareTo(((DataSegment) b).getId());
           } else {
-            throw new IllegalStateException("WTF??");
+            throw new IllegalStateException("BAD");
           }
         }
     );

services/src/main/java/org/apache/druid/cli/DumpSegment.java

@@ -189,7 +189,7 @@ public class DumpSegment extends GuiceRunnable
           runBitmaps(injector, index);
           break;
         default:
-          throw new ISE("WTF?! dumpType[%s] has no handler?", dumpType);
+          throw new ISE("dumpType[%s] has no handler", dumpType);
       }
     }
     catch (Exception e) {

sql/src/main/java/org/apache/druid/sql/calcite/expression/BinaryOperatorConversion.java

@@ -60,7 +60,7 @@ public class BinaryOperatorConversion implements SqlOperatorConversion
         rexNode,
         operands -> {
           if (operands.size() < 2) {
-            throw new ISE("WTF?! Got binary operator[%s] with %s args?", operator.getName(), operands.size());
+            throw new ISE("Got binary operator[%s] with %s args", operator.getName(), operands.size());
           }
 
           return DruidExpression.fromExpression(
@@ -92,7 +92,7 @@ public class BinaryOperatorConversion implements SqlOperatorConversion
         rexNode,
         operands -> {
           if (operands.size() < 2) {
-            throw new ISE("WTF?! Got binary operator[%s] with %s args?", operator.getName(), operands.size());
+            throw new ISE("Got binary operator[%s] with %s args", operator.getName(), operands.size());
           }
 
           return DruidExpression.fromExpression(

sql/src/main/java/org/apache/druid/sql/calcite/expression/Expressions.java

@@ -221,7 +221,7 @@ public class Expressions
     final RexInputRef ref = (RexInputRef) rexNode;
     final String columnName = rowSignature.getColumnName(ref.getIndex());
     if (columnName == null) {
-      throw new ISE("WTF?! Expression referred to nonexistent index[%d]", ref.getIndex());
+      throw new ISE("Expression referred to nonexistent index[%d]", ref.getIndex());
     }
 
     return DruidExpression.fromColumn(columnName);
@@ -490,7 +490,7 @@ public class Expressions
                || kind == SqlKind.LESS_THAN
                || kind == SqlKind.LESS_THAN_OR_EQUAL) {
       final List<RexNode> operands = ((RexCall) rexNode).getOperands();
-      Preconditions.checkState(operands.size() == 2, "WTF?! Expected 2 operands, got[%,d]", operands.size());
+      Preconditions.checkState(operands.size() == 2, "Expected 2 operands, got[%,d]", operands.size());
       boolean flip = false;
       RexNode lhs = operands.get(0);
       RexNode rhs = operands.get(1);
@@ -525,7 +525,7 @@ public class Expressions
             flippedKind = SqlKind.GREATER_THAN_OR_EQUAL;
             break;
           default:
-            throw new ISE("WTF?! Kind[%s] not expected here", kind);
+            throw new ISE("Kind[%s] not expected here", kind);
         }
       } else {
         flippedKind = kind;
@@ -632,7 +632,7 @@ public class Expressions
           filter = Bounds.lessThanOrEqualTo(boundRefKey, val);
           break;
         default:
-          throw new IllegalStateException("WTF?! Shouldn't have got here...");
+          throw new IllegalStateException("Shouldn't have got here");
       }
 
       return filter;
@@ -770,7 +770,7 @@ public class Expressions
       case LESS_THAN_OR_EQUAL:
         return Bounds.lessThan(boundRefKey, String.valueOf(interval.getEndMillis()));
       default:
-        throw new IllegalStateException("WTF?! Shouldn't have got here...");
+        throw new IllegalStateException("Shouldn't have got here");
     }
   }
 }

sql/src/main/java/org/apache/druid/sql/calcite/expression/OperatorConversions.java

@@ -195,7 +195,7 @@ public class OperatorConversions
       final RexInputRef ref = (RexInputRef) rexNode;
       final String columnName = rowSignature.getColumnName(ref.getIndex());
       if (columnName == null) {
-        throw new ISE("WTF?! PostAgg referred to nonexistent index[%d]", ref.getIndex());
+        throw new ISE("PostAggregator referred to nonexistent index[%d]", ref.getIndex());
       }
 
       return new FieldAccessPostAggregator(

sql/src/main/java/org/apache/druid/sql/calcite/expression/builtin/CeilOperatorConversion.java

@@ -23,6 +23,7 @@ import org.apache.calcite.rex.RexCall;
 import org.apache.calcite.rex.RexNode;
 import org.apache.calcite.sql.SqlOperator;
 import org.apache.calcite.sql.fun.SqlStdOperatorTable;
+import org.apache.druid.java.util.common.ISE;
 import org.apache.druid.segment.column.RowSignature;
 import org.apache.druid.sql.calcite.expression.DruidExpression;
 import org.apache.druid.sql.calcite.expression.OperatorConversions;
@@ -59,8 +60,7 @@ public class CeilOperatorConversion implements SqlOperatorConversion
           TimeFloorOperatorConversion.toTimestampFloorOrCeilArgs(plannerContext, rowSignature, call.getOperands())
       );
     } else {
-      // WTF? CEIL with the wrong number of arguments?
+      throw new ISE("Unexpected number of arguments");
-      return null;
     }
   }
 }

sql/src/main/java/org/apache/druid/sql/calcite/expression/builtin/FloorOperatorConversion.java

@@ -23,6 +23,7 @@ import org.apache.calcite.rex.RexCall;
 import org.apache.calcite.rex.RexNode;
 import org.apache.calcite.sql.SqlOperator;
 import org.apache.calcite.sql.fun.SqlStdOperatorTable;
+import org.apache.druid.java.util.common.ISE;
 import org.apache.druid.segment.column.RowSignature;
 import org.apache.druid.sql.calcite.expression.DruidExpression;
 import org.apache.druid.sql.calcite.expression.OperatorConversions;
@@ -59,8 +60,7 @@ public class FloorOperatorConversion implements SqlOperatorConversion
           TimeFloorOperatorConversion.toTimestampFloorOrCeilArgs(plannerContext, rowSignature, call.getOperands())
       );
     } else {
-      // WTF? FLOOR with the wrong number of arguments?
+      throw new ISE("Unexpected number of arguments");
-      return null;
     }
   }
 }

sql/src/main/java/org/apache/druid/sql/calcite/filtration/BoundValue.java

@@ -76,7 +76,7 @@ public class BoundValue implements Comparable<BoundValue>
   public int compareTo(BoundValue o)
   {
     if (!comparator.equals(o.comparator)) {
-      throw new ISE("WTF?! Comparator mismatch?!");
+      throw new ISE("Comparator mismatch");
     }
     return comparator.compare(value, o.value);
   }

sql/src/main/java/org/apache/druid/sql/calcite/filtration/CombineAndSimplifyBounds.java

@@ -153,7 +153,8 @@ public class CombineAndSimplifyBounds extends BottomUpTransform
         // We found a simplification. Remove the old filters and add new ones.
         for (final BoundDimFilter bound : filterList) {
           if (!newChildren.remove(bound)) {
-            throw new ISE("WTF?! Tried to remove bound but couldn't?");
+            // Don't expect this to happen, but include it as a sanity check.
+            throw new ISE("Tried to remove bound, but couldn't");
           }
         }
 

sql/src/main/java/org/apache/druid/sql/calcite/filtration/ConvertSelectorsToIns.java

@@ -85,7 +85,8 @@ public class ConvertSelectorsToIns extends BottomUpTransform
           for (final SelectorDimFilter selector : filterList) {
             values.add(selector.getValue());
             if (!children.remove(selector)) {
-              throw new ISE("WTF?! Tried to remove selector but couldn't?");
+              // Don't expect this to happen, but include it as a sanity check.
+              throw new ISE("Tried to remove selector but couldn't");
             }
           }
 

sql/src/main/java/org/apache/druid/sql/calcite/filtration/Filtration.java

@@ -141,7 +141,8 @@ public class Filtration
     );
 
     if (!transformed.getIntervals().equals(ImmutableList.of(eternity()))) {
-      throw new ISE("WTF?! optimizeFilterOnly was about to return filtration with intervals?!");
+      // Should not happen, but include as a sanity check to be sure.
+      throw new ISE("optimizeFilterOnly was about to return filtration with intervals");
     }
 
     return transformed;

sql/src/main/java/org/apache/druid/sql/calcite/planner/DruidConvertletTable.java

@@ -149,7 +149,7 @@ public class DruidConvertletTable implements SqlRexConvertletTable
             )
         );
       } else {
-        throw new ISE("WTF?! Should not have got here, operator was: %s", operator);
+        throw new ISE("Should not have got here, operator was: %s", operator);
       }
     }
   }

sql/src/main/java/org/apache/druid/sql/calcite/rel/PartialDruidQuery.java

@@ -393,7 +393,7 @@ public class PartialDruidQuery
       case SCAN:
         return scan;
       default:
-        throw new ISE("WTF?! Unknown stage: %s", currentStage);
+        throw new ISE("Unknown stage: %s", currentStage);
     }
   }
 

sql/src/main/java/org/apache/druid/sql/calcite/rule/ProjectAggregatePruneUnusedCallRule.java

@@ -61,7 +61,7 @@ public class ProjectAggregatePruneUnusedCallRule extends RelOptRule
     final int fieldCount = aggregate.getGroupCount() + aggregate.getAggCallList().size();
     if (fieldCount != aggregate.getRowType().getFieldCount()) {
       throw new ISE(
-          "WTF, expected[%s] to have[%s] fields but it had[%s]",
+          "Expected[%s] to have[%s] fields but it had[%s]",
           aggregate,
           fieldCount,
           aggregate.getRowType().getFieldCount()