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Various cleanups in instrumentation-jvm #1014

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Various cleanups in instrumentation-jvm #1014

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9ebe41e
Various cleanups in instrumentation-jvm
mimaison Oct 1, 2024
ee36ad0
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mimaison Oct 1, 2024
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251 changes: 130 additions & 121 deletions ...c/main/java/io/prometheus/metrics/instrumentation/jvm/JvmMemoryPoolAllocationMetrics.java
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Original file line number Diff line number Diff line change
Expand Up @@ -5,28 +5,34 @@
import io.prometheus.metrics.config.PrometheusProperties;
import io.prometheus.metrics.core.metrics.Counter;
import io.prometheus.metrics.model.registry.PrometheusRegistry;

import javax.management.Notification;
import javax.management.NotificationEmitter;
import javax.management.NotificationListener;
import javax.management.openmbean.CompositeData;
import java.lang.management.GarbageCollectorMXBean;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryUsage;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.management.Notification;
import javax.management.NotificationEmitter;
import javax.management.NotificationListener;
import javax.management.openmbean.CompositeData;

/**
* JVM memory allocation metrics. The {@link JvmMemoryPoolAllocationMetrics} are registered as part of the {@link JvmMetrics} like this:
* JVM memory allocation metrics. The {@link JvmMemoryPoolAllocationMetrics} are registered as part
* of the {@link JvmMetrics} like this:
*
* <pre>{@code
* JvmMetrics.builder().register();
* JvmMetrics.builder().register();
* }</pre>
* However, if you want only the {@link JvmMemoryPoolAllocationMetrics} you can also register them directly:
*
* However, if you want only the {@link JvmMemoryPoolAllocationMetrics} you can also register them
* directly:
*
* <pre>{@code
* JvmMemoryAllocationMetrics.builder().register();
* JvmMemoryAllocationMetrics.builder().register();
* }</pre>
*
* Example metrics being exported:
*
* <pre>
* # HELP jvm_memory_pool_allocated_bytes_total Total bytes allocated in a given JVM memory pool. Only updated after GC, not continuously.
* # TYPE jvm_memory_pool_allocated_bytes_total counter
Expand All @@ -40,131 +46,134 @@
*/
public class JvmMemoryPoolAllocationMetrics {

private static final String JVM_MEMORY_POOL_ALLOCATED_BYTES_TOTAL = "jvm_memory_pool_allocated_bytes_total";
private static final String JVM_MEMORY_POOL_ALLOCATED_BYTES_TOTAL =
"jvm_memory_pool_allocated_bytes_total";

private final List<GarbageCollectorMXBean> garbageCollectorBeans;

private JvmMemoryPoolAllocationMetrics(
List<GarbageCollectorMXBean> garbageCollectorBeans, PrometheusProperties config) {
this.garbageCollectorBeans = garbageCollectorBeans;
}

private void register(PrometheusRegistry registry) {

Counter allocatedCounter =
Counter.builder()
.name(JVM_MEMORY_POOL_ALLOCATED_BYTES_TOTAL)
.help(
"Total bytes allocated in a given JVM memory pool. Only updated after GC, not continuously.")
.labelNames("pool")
.register(registry);

AllocationCountingNotificationListener listener =
new AllocationCountingNotificationListener(allocatedCounter);
for (GarbageCollectorMXBean garbageCollectorMXBean : garbageCollectorBeans) {
if (garbageCollectorMXBean instanceof NotificationEmitter) {
((NotificationEmitter) garbageCollectorMXBean)
.addNotificationListener(listener, null, null);
}
}
}

private final PrometheusProperties config;
private final List<GarbageCollectorMXBean> garbageCollectorBeans;
static class AllocationCountingNotificationListener implements NotificationListener {

private final Map<String, Long> lastMemoryUsage = new HashMap<>();
private final Counter counter;

private JvmMemoryPoolAllocationMetrics(List<GarbageCollectorMXBean> garbageCollectorBeans, PrometheusProperties config) {
this.garbageCollectorBeans = garbageCollectorBeans;
this.config = config;
AllocationCountingNotificationListener(Counter counter) {
this.counter = counter;
}

private void register(PrometheusRegistry registry) {
@Override
public synchronized void handleNotification(Notification notification, Object handback) {
GarbageCollectionNotificationInfo info =
GarbageCollectionNotificationInfo.from((CompositeData) notification.getUserData());
GcInfo gcInfo = info.getGcInfo();
Map<String, MemoryUsage> memoryUsageBeforeGc = gcInfo.getMemoryUsageBeforeGc();
Map<String, MemoryUsage> memoryUsageAfterGc = gcInfo.getMemoryUsageAfterGc();
for (Map.Entry<String, MemoryUsage> entry : memoryUsageBeforeGc.entrySet()) {
String memoryPool = entry.getKey();
long before = entry.getValue().getUsed();
long after = memoryUsageAfterGc.get(memoryPool).getUsed();
handleMemoryPool(memoryPool, before, after);
}
}

Counter allocatedCounter = Counter.builder()
.name(JVM_MEMORY_POOL_ALLOCATED_BYTES_TOTAL)
.help("Total bytes allocated in a given JVM memory pool. Only updated after GC, not continuously.")
.labelNames("pool")
.register(registry);
// Visible for testing
void handleMemoryPool(String memoryPool, long before, long after) {
/*
* Calculate increase in the memory pool by comparing memory used
* after last GC, before this GC, and after this GC.
* See ascii illustration below.
* Make sure to count only increases and ignore decreases.
* (Typically a pool will only increase between GCs or during GCs, not both.
* E.g. eden pools between GCs. Survivor and old generation pools during GCs.)
*
* |<-- diff1 -->|<-- diff2 -->|
* Timeline: |-- last GC --| |---- GC -----|
* ___^__ ___^____ ___^___
* Mem. usage vars: / last \ / before \ / after \
*/

// Get last memory usage after GC and remember memory used after for next time
long last = getAndSet(lastMemoryUsage, memoryPool, after);
// Difference since last GC
long diff1 = before - last;
// Difference during this GC
long diff2 = after - before;
// Make sure to only count increases
if (diff1 < 0) {
diff1 = 0;
}
if (diff2 < 0) {
diff2 = 0;
}
long increase = diff1 + diff2;
if (increase > 0) {
counter.labelValues(memoryPool).inc(increase);
}
}

AllocationCountingNotificationListener listener = new AllocationCountingNotificationListener(allocatedCounter);
for (GarbageCollectorMXBean garbageCollectorMXBean : garbageCollectorBeans) {
if (garbageCollectorMXBean instanceof NotificationEmitter) {
((NotificationEmitter) garbageCollectorMXBean).addNotificationListener(listener, null, null);
}
}
private static long getAndSet(Map<String, Long> map, String key, long value) {
Long last = map.put(key, value);
return last == null ? 0 : last;
}
}

public static Builder builder() {
return new Builder(PrometheusProperties.get());
}

public static Builder builder(PrometheusProperties config) {
return new Builder(config);
}

public static class Builder {

private final PrometheusProperties config;
private List<GarbageCollectorMXBean> garbageCollectorBeans;

static class AllocationCountingNotificationListener implements NotificationListener {

private final Map<String, Long> lastMemoryUsage = new HashMap<String, Long>();
private final Counter counter;

AllocationCountingNotificationListener(Counter counter) {
this.counter = counter;
}

@Override
public synchronized void handleNotification(Notification notification, Object handback) {
GarbageCollectionNotificationInfo info = GarbageCollectionNotificationInfo.from((CompositeData) notification.getUserData());
GcInfo gcInfo = info.getGcInfo();
Map<String, MemoryUsage> memoryUsageBeforeGc = gcInfo.getMemoryUsageBeforeGc();
Map<String, MemoryUsage> memoryUsageAfterGc = gcInfo.getMemoryUsageAfterGc();
for (Map.Entry<String, MemoryUsage> entry : memoryUsageBeforeGc.entrySet()) {
String memoryPool = entry.getKey();
long before = entry.getValue().getUsed();
long after = memoryUsageAfterGc.get(memoryPool).getUsed();
handleMemoryPool(memoryPool, before, after);
}
}

// Visible for testing
void handleMemoryPool(String memoryPool, long before, long after) {
/*
* Calculate increase in the memory pool by comparing memory used
* after last GC, before this GC, and after this GC.
* See ascii illustration below.
* Make sure to count only increases and ignore decreases.
* (Typically a pool will only increase between GCs or during GCs, not both.
* E.g. eden pools between GCs. Survivor and old generation pools during GCs.)
*
* |<-- diff1 -->|<-- diff2 -->|
* Timeline: |-- last GC --| |---- GC -----|
* ___^__ ___^____ ___^___
* Mem. usage vars: / last \ / before \ / after \
*/

// Get last memory usage after GC and remember memory used after for next time
long last = getAndSet(lastMemoryUsage, memoryPool, after);
// Difference since last GC
long diff1 = before - last;
// Difference during this GC
long diff2 = after - before;
// Make sure to only count increases
if (diff1 < 0) {
diff1 = 0;
}
if (diff2 < 0) {
diff2 = 0;
}
long increase = diff1 + diff2;
if (increase > 0) {
counter.labelValues(memoryPool).inc(increase);
}
}

private static long getAndSet(Map<String, Long> map, String key, long value) {
Long last = map.put(key, value);
return last == null ? 0 : last;
}
private Builder(PrometheusProperties config) {
this.config = config;
}

public static Builder builder() {
return new Builder(PrometheusProperties.get());
/** Package private. For testing only. */
Builder withGarbageCollectorBeans(List<GarbageCollectorMXBean> garbageCollectorBeans) {
this.garbageCollectorBeans = garbageCollectorBeans;
return this;
}

public static Builder builder(PrometheusProperties config) {
return new Builder(config);
public void register() {
register(PrometheusRegistry.defaultRegistry);
}

public static class Builder {

private final PrometheusProperties config;
private List<GarbageCollectorMXBean> garbageCollectorBeans;

private Builder(PrometheusProperties config) {
this.config = config;
}

/**
* Package private. For testing only.
*/
Builder withGarbageCollectorBeans(List<GarbageCollectorMXBean> garbageCollectorBeans) {
this.garbageCollectorBeans = garbageCollectorBeans;
return this;
}

public void register() {
register(PrometheusRegistry.defaultRegistry);
}

public void register(PrometheusRegistry registry) {
List<GarbageCollectorMXBean> garbageCollectorBeans = this.garbageCollectorBeans;
if (garbageCollectorBeans == null) {
garbageCollectorBeans = ManagementFactory.getGarbageCollectorMXBeans();
}
new JvmMemoryPoolAllocationMetrics(garbageCollectorBeans, config).register(registry);
}
public void register(PrometheusRegistry registry) {
List<GarbageCollectorMXBean> garbageCollectorBeans = this.garbageCollectorBeans;
if (garbageCollectorBeans == null) {
garbageCollectorBeans = ManagementFactory.getGarbageCollectorMXBeans();
}
new JvmMemoryPoolAllocationMetrics(garbageCollectorBeans, config).register(registry);
}
}
}
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