KAFKA-19697: Fix unregistering connectorStatusMetrics NPE if tasks fa… #20564
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Contributor
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Thanks for catching the bug, @fanyang. Probably easy to nail the scenario in a a small test case to assertDoesNotThrow(() -> metricsGroup.recordTaskRemoved(new ConnectorTaskId('nonadded-task')), "should not throw NPE"). |
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Author
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Added UT. Thanks @zheguang |
zheguang
approved these changes
Sep 24, 2025
| @ValueSource(booleans = {true, false}) | ||
| public void testConnectorStatusMetricsGroup_tasksFailedToStart(boolean enableTopicCreation) { | ||
| setup(enableTopicCreation); | ||
| ConcurrentMap<ConnectorTaskId, WorkerTask<?, ?>> tasks = new ConcurrentHashMap<>(); |
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Minor: to help with reading the test, I'd name this as emptyTasks instantiated with immutable empty map.
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Thanks. It's hard to create an immutable ConcurrentHashMap. I directly pass an empty ConcurrentHashMap to metrics group.
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The PR fixed an NPE when connectorStatusMetrics unregistering task. The issue will happen if a connector has more than 1 task on one worker and these tasks fail to start. For example, if the DNS cant resolve producer URL, tasks will fail to build. If these tasks failing to start, ConnectorStatusMetricsGroup will unregister them. After first task unregistered , connectorStatusMetrics removed connector. When second task calles recordTaskRemoved(), connectorStatusMetrics is empty, so connectorStatusMetrics.get(connectorTaskId.connector()).close(); will throw NPE.
Like in method recordTaskAdded(), this fix checkes connectorStatusMetrics at the beginning of method recordTaskRemoved().