slfan1989 commented on code in PR #8747:
URL: https://github.com/apache/hadoop/pull/8747#discussion_r4092081972
##########
hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/scheduler/capacity/QueueManagementDynamicEditPolicy.java:
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@@ -183,47 +183,52 @@ List<QueueManagementChange> manageAutoCreatedLeafQueues()
List<QueueManagementChange> queueManagementChanges =
Collections.emptyList();
- if (!parentQueue.shouldFailAutoCreationWhenGuaranteedCapacityExceeded()) {
-
- AutoCreatedQueueManagementPolicy policyClazz =
- parentQueue.getAutoCreatedQueueManagementPolicy();
- long startTime = 0;
- try {
- startTime = clock.getTime();
-
- queueManagementChanges = policyClazz.computeQueueManagementChanges();
-
- //Scheduler update is asynchronous
- if (queueManagementChanges.size() > 0) {
- QueueManagementChangeEvent queueManagementChangeEvent =
- new QueueManagementChangeEvent(parentQueue,
- queueManagementChanges);
- scheduler.getRMContext().getDispatcher().getEventHandler().handle(
- queueManagementChangeEvent);
- }
-
- if (LOG.isDebugEnabled()) {
- LOG.debug("{} uses {} millisecond" + " to run",
- policyClazz.getClass().getName(), clock.getTime() - startTime);
+ parentQueue.getReadLock().lock();
Review Comment:
This read lock introduces a read-to-write lock upgrade deadlock.
`GuaranteedOrZeroCapacityOverTimePolicy.computeQueueManagementChanges()`
calls
`managedParentQueue.updateTemplateCapacitiesForAbsoluteResource()`, which
unconditionally acquires the same parent's write lock before checking the
capacity mode.
Since `ReentrantReadWriteLock` does not support upgrading a held read lock
to the write lock, the monitor thread will block on itself whenever it reaches
this path, even without a concurrent queue refresh.
Please revise the locking strategy to accommodate this write-lock
acquisition and add a bounded regression test exercising the real policy
through `QueueManagementDynamicEditPolicy`.
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