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Improve global-cached-lookups metric reporting (#13219) 

It was found that the namespace/cache/heapSizeInBytes metric that tracks the total heap size in bytes of all lookup caches loaded on a service instance was being under reported. We were not accounting for the memory overhead of the String object, which I've found in testing to be ~40 bytes. While this overhead may be java version dependent, it should not vary much, and accounting for this provides a better estimate. Also fixed some logging, and reading bytes from the JDBI result set a little more efficient by saving hash table lookups. Also added some of the lookup metrics to the default statsD emitter metric whitelist.
This commit is contained in:
zachjsh 2022-10-13 18:51:54 -04:00 committed by GitHub
parent 45dfd679e9
commit 2f2fe20089
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6 changed files with 14 additions and 8 deletions
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5
extensions-contrib/statsd-emitter/src/main/resources/defaultMetricDimensions.json
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@ -169,5 +169,8 @@
"segment/compacted/bytes" : { "dimensions" : ["dataSource"], "type" : "gauge" },
"segment/compacted/count" : { "dimensions" : ["dataSource"], "type" : "count" },
"interval/compacted/count" : { "dimensions" : ["dataSource"], "type" : "count" }
"interval/compacted/count" : { "dimensions" : ["dataSource"], "type" : "count" },
"namespace/cache/numEntries" : { "dimensions" : [], "type" : "gauge" },
"namespace/cache/heapSizeInBytes" : { "dimensions" : [], "type" : "gauge" }
}

3
extensions-core/lookups-cached-global/src/main/java/org/apache/druid/data/input/MapPopulator.java
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@ -245,7 +245,8 @@ public class MapPopulator<K, V>
{
if (null != o) {
if (o.getClass().getName().equals(STRING_CLASS_NAME)) {
return ((String) (o)).length();
// Each String object has ~40 bytes of overhead
return ((long) ((String) (o)).length() * Character.BYTES) + 40;
} else if (o.getClass().getName().equals(DOUBLE_CLASS_NAME)) {
return 8;
} else if (o.getClass().getName().equals(FLOAT_CLASS_NAME)) {

4
extensions-core/lookups-cached-global/src/main/java/org/apache/druid/server/lookup/namespace/JdbcCacheGenerator.java
View File

@ -105,7 +105,7 @@ public final class JdbcCacheGenerator implements CacheGenerator<JdbcExtractionNa
);
final long duration = System.nanoTime() - startNs;
LOG.info(
"Finished loading %,d values (%d bytes) for [%s] in %,d ns",
"Finished loading %d values (%d bytes) for [%s] in %d ns",
populateResult.getEntries(),
populateResult.getBytes(),
entryId,
@ -151,7 +151,7 @@ public final class JdbcCacheGenerator implements CacheGenerator<JdbcExtractionNa
final String keyColumn = namespace.getKeyColumn();
return handle.createQuery(buildLookupQuery(table, filter, keyColumn, valueColumn))
.map((index1, r1, ctx1) -> new Pair<>(r1.getString(keyColumn), r1.getString(valueColumn)))
.map((index1, r1, ctx1) -> new Pair<>(r1.getString(1), r1.getString(2)))
.iterator();
}

2
extensions-core/lookups-cached-global/src/main/java/org/apache/druid/server/lookup/namespace/UriCacheGenerator.java
View File

@ -156,7 +156,7 @@ public final class UriCacheGenerator implements CacheGenerator<UriExtractionName
);
final long duration = System.nanoTime() - startNs;
log.info(
"Finished loading %,d values (%d bytes) from %,d lines for [%s] in %,d ns",
"Finished loading %d values (%d bytes) from %d lines for [%s] in %d ns",
populateResult.getEntries(),
populateResult.getBytes(),
populateResult.getLines(),

4
extensions-core/lookups-cached-global/src/main/java/org/apache/druid/server/lookup/namespace/cache/OnHeapNamespaceExtractionCacheManager.java vendored
View File

@ -150,7 +150,9 @@ public class OnHeapNamespaceExtractionCacheManager extends NamespaceExtractionCa
size += key.length() + value.length();
}
}
// Each String object has ~40 bytes of overhead, and x 2 for key and value strings
long heapSizeInBytes = (80 * numEntries) + size * Character.BYTES;
serviceEmitter.emit(ServiceMetricEvent.builder().build("namespace/cache/numEntries", numEntries));
serviceEmitter.emit(ServiceMetricEvent.builder().build("namespace/cache/heapSizeInBytes", size * Character.BYTES));
serviceEmitter.emit(ServiceMetricEvent.builder().build("namespace/cache/heapSizeInBytes", heapSizeInBytes));
}
}

4
extensions-core/lookups-cached-global/src/test/java/org/apache/druid/data/input/MapPopulatorTest.java
View File

@ -39,7 +39,7 @@ public class MapPopulatorTest
public void test_getByteLengthOfObject_string_stringLength()
{
String o = "string";
Assert.assertEquals(o.length(), MapPopulator.getByteLengthOfObject(o));
Assert.assertEquals((o.length() * Character.BYTES) + 40, MapPopulator.getByteLengthOfObject(o));
}
@Test
@ -184,7 +184,7 @@ public class MapPopulatorTest
Assert.assertEquals(expectedMap, map);
Assert.assertEquals(4, result.getEntries());
Assert.assertEquals(0, result.getLines());
Assert.assertEquals(16L, result.getBytes());
Assert.assertEquals(192L, result.getBytes());
}
@Test