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Posted to commits@pulsar.apache.org by GitBox <gi...@apache.org> on 2022/02/05 17:31:22 UTC
[GitHub] [pulsar] merlimat opened a new pull request #14131: Fixed deadlock on txn semaphore permit exhaustion
merlimat opened a new pull request #14131:
URL: https://github.com/apache/pulsar/pull/14131
### Motivation
Removing semaphore on the end of transactions operations. The semaphore is not very useful here as we are already closing the transactions (backpressure should eventually be applied at the starting of the transactions).
The semaphore here is being acquired from a BK callback thread and it causes a deadlock in broker when the semaphore is full, because the response that will release the permits on the semaphore are coming from either the same thread or a thread in the same condition.
```
sun.misc.Unsafe.park(Unsafe.java)
java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:997)
java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1304)
java.util.concurrent.Semaphore.acquire(Semaphore.java:312)
org.apache.pulsar.broker.transaction.buffer.impl.TransactionBufferHandlerImpl.canSendRequest(TransactionBufferHandlerImpl.java:216)
org.apache.pulsar.broker.transaction.buffer.impl.TransactionBufferHandlerImpl.endTxnOnTopic(TransactionBufferHandlerImpl.java:93)
org.apache.pulsar.broker.transaction.buffer.impl.TransactionBufferClientImpl.commitTxnOnTopic(TransactionBufferClientImpl.java:50)
org.apache.pulsar.broker.TransactionMetadataStoreService.lambda$null$23(TransactionMetadataStoreService.java:484)
org.apache.pulsar.broker.TransactionMetadataStoreService$$Lambda$1253.accept()
java.util.ArrayList.forEach(ArrayList.java:1257)
org.apache.pulsar.broker.TransactionMetadataStoreService.lambda$endTxnInTransactionBuffer$25(TransactionMetadataStoreService.java:481)
org.apache.pulsar.broker.TransactionMetadataStoreService$$Lambda$1251.accept()
java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:760)
java.util.concurrent.CompletableFuture.uniWhenCompleteStage(CompletableFuture.java:778)
java.util.concurrent.CompletableFuture.whenComplete(CompletableFuture.java:2140)
org.apache.pulsar.broker.TransactionMetadataStoreService.endTxnInTransactionBuffer(TransactionMetadataStoreService.java:458)
org.apache.pulsar.broker.TransactionMetadataStoreService.lambda$null$11(TransactionMetadataStoreService.java:349)
org.apache.pulsar.broker.TransactionMetadataStoreService$$Lambda$1309.accept()
java.util.concurrent.CompletableFuture.uniAccept(CompletableFuture.java:656)
java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:632)
java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:474)
java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:1962)
org.apache.pulsar.transaction.coordinator.impl.MLTransactionLogImpl$3.addComplete(MLTransactionLogImpl.java:160)
org.apache.bookkeeper.mledger.impl.OpAddEntry.safeRun(OpAddEntry.java:228)
org.apache.bookkeeper.common.util.SafeRunnable.run(SafeRunnable.java:36)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
java.lang.Thread.run(Thread.java:748)
```
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[GitHub] [pulsar] codelipenghui commented on pull request #14131: Fixed deadlock on txn semaphore permit exhaustion
Posted by GitBox <gi...@apache.org>.
codelipenghui commented on pull request #14131:
URL: https://github.com/apache/pulsar/pull/14131#issuecomment-1030802730
> backpressure should eventually be applied at the start of the transactions
I remember the semaphore is for limiting the transaction buffer calls while reply transaction logs. @congbobo184 Please help double confirm.
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[GitHub] [pulsar] github-actions[bot] removed a comment on pull request #14131: Fixed deadlock on txn semaphore permit exhaustion
Posted by GitBox <gi...@apache.org>.
github-actions[bot] removed a comment on pull request #14131:
URL: https://github.com/apache/pulsar/pull/14131#issuecomment-1030665433
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[GitHub] [pulsar] codelipenghui merged pull request #14131: Fixed deadlock on txn semaphore permit exhaustion
Posted by GitBox <gi...@apache.org>.
codelipenghui merged pull request #14131:
URL: https://github.com/apache/pulsar/pull/14131
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[GitHub] [pulsar] github-actions[bot] commented on pull request #14131: Fixed deadlock on txn semaphore permit exhaustion
Posted by GitBox <gi...@apache.org>.
github-actions[bot] commented on pull request #14131:
URL: https://github.com/apache/pulsar/pull/14131#issuecomment-1030665429
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