Fix Flink IllegalThreadStateException on Java 8 #36730

aIbrahiim · 2025-11-05T14:16:15Z

Fixes: #32949
Successful Run: https://github.com/aIbrahiim/beam/actions/runs/19104037201/job/54582948548

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gemini-code-assist · 2025-11-05T14:16:33Z

Summary of Changes

Hello @aIbrahiim, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a known issue where Flink jobs running on Java 8 in attached mode could encounter an IllegalThreadStateException due to the premature destruction of ThreadGroup instances during Flink's internal cleanup. The solution introduces a targeted workaround that temporarily extends the lifecycle of the relevant ThreadGroup for a brief period, ensuring Flink's cleanup processes can complete without interruption and thereby stabilizing job execution on Java 8 environments.

Highlights

Fix for IllegalThreadStateException on Java 8: This pull request introduces a specific fix to prevent an IllegalThreadStateException that can occur when running Flink jobs on Java 8, particularly in attached execution mode.
Thread Group Protection Mechanism: A new mechanism has been implemented to temporarily protect the current ThreadGroup from premature destruction. This is achieved by adding it to a static protectedThreadGroups set and then releasing it after a short delay (2 seconds) via a dedicated cleanup thread.
Conditional Application: The ensureFlinkCleanupComplete method, which encapsulates this protection logic, is only invoked when the Java runtime version is detected as Java 8 and the Flink job is executed in attached mode.

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github-actions · 2025-11-05T15:37:41Z

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Abacn · 2025-11-05T16:33:11Z

...ers/flink/src/main/java/org/apache/beam/runners/flink/FlinkPipelineExecutionEnvironment.java

  }

+  /** Prevents ThreadGroup destruction while Flink cleanup threads are still running. */
+  private void ensureFlinkCleanupComplete(Object executionEnv) {


there is an executionEnv but not used. What is the consideration here?

Ahh i added for any future checks like stream or batching, or local env and so on.

Abacn · 2025-11-05T16:45:45Z

...ers/flink/src/main/java/org/apache/beam/runners/flink/FlinkPipelineExecutionEnvironment.java

+  private void ensureFlinkCleanupComplete(Object executionEnv) {
+    String javaVersion = System.getProperty("java.version");
+    if (javaVersion == null || !javaVersion.startsWith("1.8")) {
+      return;


Busy wait is generally not desired but for band-aid fix I think it's fine. We should narrow the scenario that introduced 2 seconds latency

this only affects in-memory flink clusters, and also only affects batch jobs (':runners:flink:1.19:validatesRunnerBatch'.). Can we call wait only for batch?

Can we check whether FlinkPipelineOptions.getFlinkMaster is a "org.apache.flink.api.java.ExecutionEnvironment.LocalEnvironment" and only do the busy wait for local environment?

Okay I agree we can narrow the scope to wait for batch jobs and detect the environment and apply it for local env.

sorry realize this parameter is actually useful. We can do

if (executionEnv instanceof org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.LocalStreamEnvironment || executionEnv instanceof org.apache.flink.api.java.ExecutionEnvironment.LocalEnvironment)

this is more reliable than check getFlinkMaster below

Added the parameter

…nts only

Amar3tto · 2025-11-05T20:14:41Z

Is it okay that PreCommit Java PVR Flink Batch previously took ~2 min, and now it takes >1 hour?
CC: @Abacn

Abacn · 2025-11-05T20:19:05Z

I don't see a difference here, the last run on this PR was 31 min: https://github.com/apache/beam/actions/runs/19112042171, a (non-cache) run on master is 30 min https://github.com/apache/beam/actions/runs/19089630209

The 1 min run are due to no change in code and skipped on gradle cache.

Abacn · 2025-11-05T21:19:11Z

I see, currently validatesPortableRunnerBatch is timing out.

aIbrahiim · 2025-11-05T21:57:43Z

I see, currently validatesPortableRunnerBatch is timing out.

I guess the timeout related to some other issue as the validatesPortableRunnerBatch doesnt run on direct Flink runner

aIbrahiim · 2025-11-05T23:11:45Z

got a successful run for PreCommit Java PVR Flink Batch on my runner in 37 minutes https://github.com/aIbrahiim/beam/actions/runs/19117606320
cc: @Abacn @Amar3tto

Fix Flink IllegalThreadStateException on Java 8

3b9091d

github-actions bot added runners flink labels Nov 5, 2025

Fixed both Spotless formatting issues

57c07f6

Amar3tto requested a review from damccorm November 5, 2025 15:18

github-actions bot added the Next Action: Reviewers label Nov 5, 2025

Abacn reviewed Nov 5, 2025

View reviewed changes

Applied Flink ThreadGroup fix to Java 8 batch jobs in local environme…

1860c25

…nts only

aIbrahiim requested a review from Abacn November 5, 2025 18:36

Added executionEnv param

77c0bc6

Abacn approved these changes Nov 5, 2025

View reviewed changes

Abacn merged commit 1d33741 into apache:master Nov 6, 2025
21 of 22 checks passed

aIbrahiim deleted the 32949-PostCommit-Java-ValidatesRunner-Flink-Java8 branch November 17, 2025 13:34

Fix Flink IllegalThreadStateException on Java 8 #36730

Fix Flink IllegalThreadStateException on Java 8 #36730

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aIbrahiim commented Nov 5, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Fixes: #32949 Successful Run: https://github.com/aIbrahiim/beam/actions/runs/19104037201/job/54582948548

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aIbrahiim commented Nov 5, 2025 •

edited

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Fixes: #32949
Successful Run: https://github.com/aIbrahiim/beam/actions/runs/19104037201/job/54582948548

aIbrahiim commented Nov 5, 2025 •

edited

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