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jvm.gc.live.data.size and max not updating for optavgpause/optthruput collectors #2874

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Merged
merged 2 commits into from
Nov 26, 2021
Merged

jvm.gc.live.data.size and max not updating for optavgpause/optthruput collectors #2874

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305ebd3
NPE when allocation pool name not set
shakuzen Nov 26, 2021
c86842c
Forcing GC does not guarantee object promotion in gen gc
shakuzen Nov 26, 2021
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5 changes: 4 additions & 1 deletion micrometer-core/src/main/java/io/micrometer/core/instrument/binder/jvm/JvmGcMetrics.java
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Original file line number Diff line number Diff line change
Expand Up @@ -195,7 +195,10 @@ private boolean isGenerationalGcConfigured() {
}

private void countPoolSizeDelta(Map<String, MemoryUsage> before, Map<String, MemoryUsage> after, Counter counter,
AtomicLong previousPoolSize, String poolName) {
AtomicLong previousPoolSize, @Nullable String poolName) {
if (poolName == null) {
return;
}
final long beforeBytes = before.get(poolName).getUsed();
final long afterBytes = after.get(poolName).getUsed();
final long delta = beforeBytes - previousPoolSize.get();
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18 changes: 11 additions & 7 deletions micrometer-core/src/test/java/io/micrometer/core/instrument/binder/jvm/JvmGcMetricsTest.java
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Expand Up @@ -34,7 +34,6 @@
import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.within;
import static org.awaitility.Awaitility.await;
import static org.junit.jupiter.api.Assumptions.assumeTrue;

/**
* Tests for {@link JvmGcMetrics}.
Expand Down Expand Up @@ -65,13 +64,18 @@ void noJvmImplementationSpecificApiSignatures() {
}

@Test
void metersAreBound() {
assertThat(registry.find("jvm.gc.live.data.size").gauge()).isNotNull();
assertThat(registry.find("jvm.gc.memory.allocated").counter()).isNotNull();
assertThat(registry.find("jvm.gc.max.data.size").gauge().value()).isGreaterThan(0);
void gcMetricsAvailableAfterGc() {
System.gc();
await().timeout(200, TimeUnit.MILLISECONDS).alias("NotificationListener takes time after GC")
.untilAsserted(() ->
assertThat(registry.find("jvm.gc.live.data.size").gauge().value()).isPositive());
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@shakuzen shakuzen Nov 26, 2021

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By forcing a GC and waiting for the notification listener to update metrics, this test does a much better job of ensuring expected metrics are available for the configured collector.

assertThat(registry.find("jvm.gc.memory.allocated").counter().count()).isPositive();
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@shakuzen shakuzen Nov 26, 2021

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This metric is still missing for optavgpause and optthruput due to the allocation pool name not being set. We don't have a CI job run with OpenJ9 because we're still waiting for CI images (possibly CircleCI-Public/cimg-openjdk#78). I think we can fix the missing allocated counter separately from this pull request because it is still an improvement to get rid of the NPE which allows updating of the live and max data size gauges.

assertThat(registry.find("jvm.gc.max.data.size").gauge().value()).isPositive();

assumeTrue(binder.isGenerationalGc);
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@shakuzen shakuzen Nov 26, 2021

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When the condition failed, the whole test was marked as skipped, but if we want to use this same test for generational and non-generational collectors, we should run the part of this test before here for both and report it as passed (not skipped) for non-generational collectors if all assertions passed before here.

assertThat(registry.find("jvm.gc.memory.promoted").counter()).isNotNull();
if (!binder.isGenerationalGc) {
return;
}
assertThat(registry.find("jvm.gc.memory.promoted").counter().count()).isPositive();
}

@Test
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