[
https://issues.apache.org/jira/browse/FLINK-7368?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16216876#comment-16216876
]
ASF GitHub Bot commented on FLINK-7368:
---------------------------------------
Github user zentol commented on a diff in the pull request:
https://github.com/apache/flink/pull/4840#discussion_r146553570
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/rest/handler/legacy/metrics/MetricStore.java
---
@@ -260,50 +293,66 @@ public String getMetric(String name, String
defaultValue) {
? value
: defaultValue;
}
- }
- /**
- * Sub-structure containing metrics of the JobManager.
- */
- public static class JobManagerMetricStore extends ComponentMetricStore {
+ public static ComponentMetricStore
unmodifiable(ComponentMetricStore source) {
+ if (source == null) {
+ return null;
+ }
+ return new
ComponentMetricStore(unmodifiableMap(source.metrics));
+ }
}
/**
* Sub-structure containing metrics of a single TaskManager.
*/
+ @ThreadSafe
public static class TaskManagerMetricStore extends ComponentMetricStore
{
- public final Set<String> garbageCollectorNames = new
HashSet<>();
+ public final Set<String> garbageCollectorNames;
+
+ public TaskManagerMetricStore() {
+ this(new ConcurrentHashMap<>(),
ConcurrentHashMap.newKeySet());
+ }
+
+ public TaskManagerMetricStore(Map<String, String> metrics,
Set<String> garbageCollectorNames) {
+ super(metrics);
+ this.garbageCollectorNames =
checkNotNull(garbageCollectorNames);
+ }
public void addGarbageCollectorName(String name) {
garbageCollectorNames.add(name);
}
+
+ public static TaskManagerMetricStore
unmodifiable(TaskManagerMetricStore source) {
--- End diff --
I'm wondering whether we really need this unmodifiable business. Yes, it's
technically a good idea, but the access to the MetricStore is limited and fully
under our control; so we _know_ that we never try to modify the map.
> MetricStore makes cpu spin at 100%
> ----------------------------------
>
> Key: FLINK-7368
> URL: https://issues.apache.org/jira/browse/FLINK-7368
> Project: Flink
> Issue Type: Bug
> Components: Metrics
> Reporter: Nico Chen
> Assignee: Piotr Nowojski
> Priority: Blocker
> Fix For: 1.4.0, 1.3.3
>
> Attachments: MyHashMap.java, MyHashMapInfiniteLoopTest.java,
> jm-jstack.log
>
>
> Flink's `MetricStore` is not thread-safe. multi-treads may acess java'
> hashmap inside `MetricStore` and can tirgger hashmap's infinte loop.
> Recently I met the case that flink jobmanager consumed 100% cpu. A part of
> stacktrace is shown below. The full jstack is in the attachment.
> {code:java}
> "ForkJoinPool-1-worker-19" daemon prio=10 tid=0x00007fbdacac9800 nid=0x64c1
> runnable [0x00007fbd7d1c2000]
> java.lang.Thread.State: RUNNABLE
> at java.util.HashMap.put(HashMap.java:494)
> at
> org.apache.flink.runtime.webmonitor.metrics.MetricStore.addMetric(MetricStore.java:176)
> at
> org.apache.flink.runtime.webmonitor.metrics.MetricStore.add(MetricStore.java:121)
> at
> org.apache.flink.runtime.webmonitor.metrics.MetricFetcher.addMetrics(MetricFetcher.java:198)
> at
> org.apache.flink.runtime.webmonitor.metrics.MetricFetcher.access$500(MetricFetcher.java:58)
> at
> org.apache.flink.runtime.webmonitor.metrics.MetricFetcher$4.onSuccess(MetricFetcher.java:188)
> at akka.dispatch.OnSuccess.internal(Future.scala:212)
> at akka.dispatch.japi$CallbackBridge.apply(Future.scala:175)
> at akka.dispatch.japi$CallbackBridge.apply(Future.scala:172)
> at scala.PartialFunction$class.applyOrElse(PartialFunction.scala:123)
> at
> scala.runtime.AbstractPartialFunction.applyOrElse(AbstractPartialFunction.scala:28)
> at
> scala.concurrent.Future$$anonfun$onSuccess$1.apply(Future.scala:117)
> at
> scala.concurrent.Future$$anonfun$onSuccess$1.apply(Future.scala:115)
> at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:32)
> at
> java.util.concurrent.ForkJoinTask$AdaptedRunnable.exec(ForkJoinTask.java:1265)
> at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:334)
> at
> java.util.concurrent.ForkJoinWorkerThread.execTask(ForkJoinWorkerThread.java:604)
> at java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:784)
> at java.util.concurrent.ForkJoinPool.work(ForkJoinPool.java:646)
> at
> java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:398)
> {code}
> There are 24 threads show same stacktrace as above to indicate they are
> spining at HashMap.put(HashMap.java:494) (I am using Java 1.7.0_6). Many
> posts indicate multi-threads accessing hashmap cause this problem and I
> reproduce the case as well. The test code is attached. I only modify the
> HashMap.transfer() by adding concurrent barriers for different treads in
> order to simulate the timing of creation of cycles in hashmap's Entry. My
> program's stacktrace shows it hangs at same line of
> HashMap(HashMap.put(HashMap.java:494)) as the stacktrace I post above.
> Even through `MetricFetcher` has a 10 seconds minimum inteverl between each
> metrics qurey, it still cannot guarntee query responses do not acess
> `MtricStore`'s hashmap concurrently. Thus I think it's a bug to fix.
>
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