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ZOOKEEPER-4952:Reduce the GC overhead of Prometheus reject exception handling #2279

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Merged
li4wang merged 1 commit into from
Aug 27, 2025
Merged

ZOOKEEPER-4952:Reduce the GC overhead of Prometheus reject exception handling #2279

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22 changes: 14 additions & 8 deletions ...rics/src/main/java/org/apache/zookeeper/metrics/prometheus/PrometheusMetricsProvider.java
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,7 @@
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
Expand Down Expand Up @@ -677,7 +677,9 @@ private Optional<ExecutorService> createExecutor() {
numWorkerThreads,
0L,
TimeUnit.MILLISECONDS,
queue, new PrometheusWorkerThreadFactory());
queue,
new PrometheusWorkerThreadFactory(),
new PrometheusRejectedExecutionHandler());
LOG.info("Executor service was created with numWorkerThreads {} and maxQueueSize {}",
numWorkerThreads,
maxQueueSize);
Expand Down Expand Up @@ -714,14 +716,18 @@ public Thread newThread(final Runnable runnable) {
}
}

private class PrometheusRejectedExecutionHandler implements RejectedExecutionHandler {
private final String queueExceededMessage = "Prometheus metrics queue size exceeded the max " + maxQueueSize;

@Override
public void rejectedExecution(final Runnable r, final ThreadPoolExecutor e) {
rateLogger.rateLimitLog(queueExceededMessage);
}
}

private void reportMetrics(final Runnable task) {
if (executorOptional.isPresent()) {
try {
executorOptional.get().submit(task);
} catch (final RejectedExecutionException e) {
rateLogger.rateLimitLog("Prometheus metrics reporting task queue size exceeded the max",
String.valueOf(maxQueueSize));
}
executorOptional.get().submit(task);
} else {
task.run();
}
Expand Down
22 changes: 14 additions & 8 deletions zookeeper-server/src/main/java/org/apache/zookeeper/server/RateLogger.java
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Original file line number Diff line number Diff line change
Expand Up @@ -46,15 +46,20 @@ public RateLogger(Logger log, long interval) {

public void flush() {
if (msg != null && count > 0) {
String log = "";
// Optimized logging using parameterized messages to reduce string concatenation overhead
if (count > 1) {
log = "[" + count + " times] ";
if (value != null) {
LOG.warn("[{} times] Message: {} Last value:{}", count, msg, value);
} else {
LOG.warn("[{} times] Message: {}", count, msg);
}
} else {
if (value != null) {
LOG.warn("Message: {} Value:{}", msg, value);
} else {
LOG.warn("Message: {}", msg);
}
}
log += "Message: " + msg;
if (value != null) {
log += " Last value:" + value;
}
LOG.warn(log);
}
msg = null;
value = null;
Expand All @@ -70,7 +75,8 @@ public void rateLimitLog(String newMsg) {
*/
public void rateLimitLog(String newMsg, String newValue) {
long now = Time.currentElapsedTime();
if (Objects.equals(newMsg, msg)) {
// Optimized string comparison: use reference equality first for constant strings
if (newMsg == msg || Objects.equals(newMsg, msg)) {
++count;
value = newValue;
if (now - timestamp >= LOG_INTERVAL) {
Expand Down