SOLR-11673: Slave doesn't commit empty index if new index appears on master by deafult.

solr/CHANGES.txt

@@ -61,6 +61,10 @@ Upgrade Notes
   This is a server side change only and clients using SolrJ won't need any changes. Clients can still use any logging
   implementation which is compatible with SLF4J.
 
+* SOLR-11673: Slave doesn't commit empty index when completely new index is detected on master during replication. 
+  To return the previous behavior pass false to skipCommitOnMasterVersionZero in slave section of replication 
+  handler configuration, or pass it to the fetchindex command.
+
 New Features
 ----------------------
 
@@ -95,6 +99,9 @@ Bug Fixes
   document. Multithreaded test for AtomicUpdateRequestProcessor was also beefed up and fixed.
   (Ishan Chattopadhyaya, Noble Paul, Amrit Sarkar, shalin)
 
+* SOLR-11673: By default slave doesn't commit empty index when completely new index appears on master. 
+  See Upgrade Notes to find a way to get back to the previous behavior. (Mikhail Khludnev)
+
 Optimizations
 ----------------------
 

solr/core/src/java/org/apache/solr/handler/IndexFetcher.java

@@ -16,6 +16,31 @@
  */
 package org.apache.solr.handler;
 
+import static org.apache.solr.common.params.CommonParams.JAVABIN;
+import static org.apache.solr.common.params.CommonParams.NAME;
+import static org.apache.solr.handler.ReplicationHandler.ALIAS;
+import static org.apache.solr.handler.ReplicationHandler.CHECKSUM;
+import static org.apache.solr.handler.ReplicationHandler.CMD_DETAILS;
+import static org.apache.solr.handler.ReplicationHandler.CMD_GET_FILE;
+import static org.apache.solr.handler.ReplicationHandler.CMD_GET_FILE_LIST;
+import static org.apache.solr.handler.ReplicationHandler.CMD_INDEX_VERSION;
+import static org.apache.solr.handler.ReplicationHandler.COMMAND;
+import static org.apache.solr.handler.ReplicationHandler.COMPRESSION;
+import static org.apache.solr.handler.ReplicationHandler.CONF_FILES;
+import static org.apache.solr.handler.ReplicationHandler.CONF_FILE_SHORT;
+import static org.apache.solr.handler.ReplicationHandler.EXTERNAL;
+import static org.apache.solr.handler.ReplicationHandler.FETCH_FROM_LEADER;
+import static org.apache.solr.handler.ReplicationHandler.FILE;
+import static org.apache.solr.handler.ReplicationHandler.FILE_STREAM;
+import static org.apache.solr.handler.ReplicationHandler.GENERATION;
+import static org.apache.solr.handler.ReplicationHandler.INTERNAL;
+import static org.apache.solr.handler.ReplicationHandler.MASTER_URL;
+import static org.apache.solr.handler.ReplicationHandler.OFFSET;
+import static org.apache.solr.handler.ReplicationHandler.SIZE;
+import static org.apache.solr.handler.ReplicationHandler.SKIP_COMMIT_ON_MASTER_VERSION_ZERO;
+import static org.apache.solr.handler.ReplicationHandler.TLOG_FILE;
+import static org.apache.solr.handler.ReplicationHandler.TLOG_FILES;
+
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
@@ -86,7 +111,7 @@ import org.apache.solr.core.DirectoryFactory;
 import org.apache.solr.core.DirectoryFactory.DirContext;
 import org.apache.solr.core.IndexDeletionPolicyWrapper;
 import org.apache.solr.core.SolrCore;
-import org.apache.solr.handler.ReplicationHandler.*;
+import org.apache.solr.handler.ReplicationHandler.FileInfo;
 import org.apache.solr.request.LocalSolrQueryRequest;
 import org.apache.solr.request.SolrQueryRequest;
 import org.apache.solr.search.SolrIndexSearcher;
@@ -99,13 +124,10 @@ import org.apache.solr.util.FileUtils;
 import org.apache.solr.util.PropertiesOutputStream;
 import org.apache.solr.util.RTimer;
 import org.apache.solr.util.RefCounted;
+import org.apache.solr.util.TestInjection;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import static org.apache.solr.common.params.CommonParams.JAVABIN;
-import static org.apache.solr.common.params.CommonParams.NAME;
-import static org.apache.solr.handler.ReplicationHandler.*;
-
 import com.google.common.base.Strings;
 
 /**
@@ -167,7 +189,7 @@ public class IndexFetcher {
 
   private boolean downloadTlogFiles = false;
 
-  private boolean skipCommitOnMasterVersionZero;
+  private boolean skipCommitOnMasterVersionZero = true;
 
   private static final String INTERRUPT_RESPONSE_MESSAGE = "Interrupted while waiting for modify lock";
 
@@ -453,6 +475,7 @@ public class IndexFetcher {
           } finally {
             iw.decref();
           }
+          assert TestInjection.injectDelayBeforeSlaveCommitRefresh();
           if (skipCommitOnMasterVersionZero) {
             openNewSearcherAndUpdateCommitPoint();
           } else {

solr/core/src/java/org/apache/solr/util/TestInjection.java

@@ -144,6 +144,8 @@ public class TestInjection {
 
   private static AtomicInteger countPrepRecoveryOpPauseForever = new AtomicInteger(0);
 
+  public static Integer delayBeforeSlaveCommitRefresh=null;
+
   public static void reset() {
     nonGracefullClose = null;
     failReplicaRequests = null;
@@ -158,6 +160,7 @@ public class TestInjection {
     waitForReplicasInSync = "true:60";
     failIndexFingerprintRequests = null;
     wrongIndexFingerprint = null;
+    delayBeforeSlaveCommitRefresh = null;
 
     for (Timer timer : timers) {
       timer.cancel();
@@ -455,4 +458,16 @@ public class TestInjection {
     return new Pair<>(Boolean.parseBoolean(val), Integer.parseInt(percent));
   }
 
+  public static boolean injectDelayBeforeSlaveCommitRefresh() {
+    if (delayBeforeSlaveCommitRefresh!=null) {
+      try {
+        log.info("Pausing IndexFetcher for {}ms", delayBeforeSlaveCommitRefresh);
+        Thread.sleep(delayBeforeSlaveCommitRefresh);
+      } catch (InterruptedException e) {
+        Thread.currentThread().interrupt();
+      }
+    }
+    return true;
+  }
+
 }

solr/core/src/test/org/apache/solr/handler/TestReplicationHandler.java

@@ -70,6 +70,7 @@ import org.apache.solr.core.SolrCore;
 import org.apache.solr.core.StandardDirectoryFactory;
 import org.apache.solr.core.snapshots.SolrSnapshotMetaDataManager;
 import org.apache.solr.util.FileUtils;
+import org.apache.solr.util.TestInjection;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.BeforeClass;
@@ -494,8 +495,10 @@ public class TestReplicationHandler extends SolrTestCaseJ4 {
   }
   
   @Test
-  @BadApple(bugUrl="https://issues.apache.org/jira/browse/SOLR-11673")
   public void doTestIndexAndConfigReplication() throws Exception {
+
+    TestInjection.delayBeforeSlaveCommitRefresh = random().nextInt(10);
+
     clearIndexWithReplication();
 
     nDocs--;
@@ -550,7 +553,6 @@ public class TestReplicationHandler extends SolrTestCaseJ4 {
     slaveJetty = createJetty(slave);
     slaveClient.close();
     slaveClient = createNewSolrClient(slaveJetty.getLocalPort());
-
     //add a doc with new field and commit on master to trigger index fetch from slave.
     index(masterClient, "id", "2000", "name", "name = " + 2000, "newname", "newname = " + 2000);
     masterClient.commit();
@@ -567,7 +569,6 @@ public class TestReplicationHandler extends SolrTestCaseJ4 {
     
     checkForSingleIndex(masterJetty);
     checkForSingleIndex(slaveJetty, true);
-    
   }
 
   @Test