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Support ZGC Cycles MXBean #2795

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Sep 27, 2021
Merged

Support ZGC Cycles MXBean #2795

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3 changes: 2 additions & 1 deletion micrometer-core/src/main/java/io/micrometer/core/instrument/binder/jvm/JvmMemory.java
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,8 @@ static Optional<MemoryPoolMXBean> getLongLivedHeapPool() {

static boolean isConcurrentPhase(String cause, String name) {
return "No GC".equals(cause)
|| "Shenandoah Cycles".equals(name);
|| "Shenandoah Cycles".equals(name)
|| "ZGC Cycles".equals(name);
}

static boolean isAllocationPool(String name) {
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63 changes: 59 additions & 4 deletions micrometer-core/src/test/java/io/micrometer/core/instrument/binder/jvm/JvmGcMetricsTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -19,14 +19,22 @@
import com.tngtech.archunit.core.domain.JavaClasses;
import com.tngtech.archunit.core.importer.ClassFileImporter;
import com.tngtech.archunit.lang.ArchRule;
import io.micrometer.core.instrument.Timer;
import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.*;
import org.junit.jupiter.api.condition.EnabledForJreRange;
import org.junit.jupiter.api.condition.JRE;

import java.lang.management.GarbageCollectorMXBean;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryPoolMXBean;
import java.util.concurrent.TimeUnit;

import static com.tngtech.archunit.core.domain.JavaClass.Predicates.resideInAPackage;
import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.methods;
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;

/**
Expand All @@ -37,6 +45,13 @@
@GcTest
class JvmGcMetricsTest {

SimpleMeterRegistry registry = new SimpleMeterRegistry();

@BeforeEach
void beforeEach() {
new JvmGcMetrics().bindTo(registry);
}

@Test
void noJvmImplementationSpecificApiSignatures() {
JavaClasses importedClasses = new ClassFileImporter().importPackages("io.micrometer.core.instrument.binder.jvm");
Expand All @@ -50,9 +65,6 @@ void noJvmImplementationSpecificApiSignatures() {

@Test
void metersAreBound() {
SimpleMeterRegistry registry = new SimpleMeterRegistry();
JvmGcMetrics binder = new JvmGcMetrics();
binder.bindTo(registry);
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);
Expand All @@ -61,6 +73,49 @@ void metersAreBound() {
assertThat(registry.find("jvm.gc.memory.promoted").counter()).isNotNull();
}

@Test
@Disabled("Garbage collection can happen before JvmGcMetrics are registered, making our metrics not match overall counts/timings")
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While the test worked consistently for me on IntelliJ with ZGC and Shenandoah, it failed on the command line because of GC happening before JvmGcMetrics is registered, so the information in the GarbageCollectorMXBeans and our metrics do not add up. This is the issue described in #2561.

// available for some platforms and distributions earlier, but broadest availability in an LTS is 17
@EnabledForJreRange(min = JRE.JAVA_17)
void gcTimingIsCorrect() {
System.gc();
long pausePhaseCount = 0;
long pauseTimeMs = 0;
long concurrentPhaseCount = 0;
long concurrentTimeMs = 0;
for (GarbageCollectorMXBean mbean : ManagementFactory.getGarbageCollectorMXBeans()) {
if (mbean.getName().contains("Pauses")) {
pausePhaseCount += mbean.getCollectionCount();
pauseTimeMs += mbean.getCollectionTime();
} else if (mbean.getName().contains("Cycles")) {
concurrentPhaseCount += mbean.getCollectionCount();
concurrentTimeMs += mbean.getCollectionTime();
}
System.out.println(mbean.getName() + " (" + mbean.getCollectionCount() + ") " + mbean.getCollectionTime() + "ms");
}
checkPhaseCount(pausePhaseCount, concurrentPhaseCount);
checkCollectionTime(pauseTimeMs, concurrentTimeMs);
}

private void checkPhaseCount(long expectedPauseCount, long expectedConcurrentCount) {
await().atMost(200, TimeUnit.MILLISECONDS).untilAsserted(() -> {
long observedPauseCount = registry.find("jvm.gc.pause").timers().stream().mapToLong(Timer::count).sum();
long observedConcurrentCount = registry.find("jvm.gc.concurrent.phase.time").timers().stream().mapToLong(Timer::count).sum();
assertThat(observedPauseCount).isEqualTo(expectedPauseCount);
assertThat(observedConcurrentCount).isEqualTo(expectedConcurrentCount);
});
}

private void checkCollectionTime(long expectedPauseTimeMs, long expectedConcurrentTimeMs) {
await().atMost(200, TimeUnit.MILLISECONDS).untilAsserted(() -> {
double observedPauseTimeMs = registry.find("jvm.gc.pause").timers().stream().mapToDouble(timer -> timer.totalTime(TimeUnit.MILLISECONDS)).sum();
double observedConcurrentTimeMs = registry.find("jvm.gc.concurrent.phase.time").timers().stream().mapToDouble(timer -> timer.totalTime(TimeUnit.MILLISECONDS)).sum();
// small difference can happen when less than 1ms timing gets rounded
assertThat(observedPauseTimeMs).isCloseTo(expectedPauseTimeMs, within(1d));
assertThat(observedConcurrentTimeMs).isCloseTo(expectedConcurrentTimeMs, within(1d));
});
}

private boolean isGenerationalGc() {
return JvmMemory.getLongLivedHeapPool().map(MemoryPoolMXBean::getName).filter(JvmMemory::isOldGenPool).isPresent();
}
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