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https://issues.apache.org/jira/browse/AMQ-9808?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18044623#comment-18044623
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ASF subversion and git services commented on AMQ-9808:
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Commit f55e5344226019badea57e8353819882a28d0bd5 in activemq's branch
refs/heads/main from Jean-Louis Monteiro
[ https://gitbox.apache.org/repos/asf?p=activemq.git;h=f55e534422 ]
AMQ-9808: Dead lock when using CRON schedule with AMQ_SCHEDULED_REPEAT (#1536)
* AMQ-9808: Dead lock when using CRON schedule with AMQ_SCHEDULED_REPEAT
* AMQ-9808: Consistency and better exception handling
> Dead lock when using CRON schedule with AMQ_SCHEDULED_REPEAT
> ------------------------------------------------------------
>
> Key: AMQ-9808
> URL: https://issues.apache.org/jira/browse/AMQ-9808
> Project: ActiveMQ
> Issue Type: Bug
> Components: Job Scheduler
> Affects Versions: 5.19.1, 5.18.7, 6.1.8
> Reporter: Jean-Louis Monteiro
> Priority: Major
> Time Spent: 1h 10m
> Remaining Estimate: 0h
>
> This bug is highlighted by the current JmsSchedulerTest@testCron() test case.
> When using a CRON expression with repeat != 0, there is a deadlock happening
> between JobSchedulerImpl and JobSchedulerStoreImpl.
> The original cron job is read inside JobSchedulerImpl.mainLoop(). That loop
> holds JobSchedulerStoreImpl.readLockIndex() for the whole iteration.
> When it hits the cron branch with repeat != 0, the code tries to spawn a new
> (non-cron) schedule by calling schedule(jobId, payload, "", delay, period,
> repeat) while the read lock is still held. schedule() writes a new
> KahaAddScheduledJobCommand, and JobSchedulerStoreImpl.process() needs the
> same indexLock in write mode. Since the scheduler thread already holds the
> read lock, it can’t acquire the write lock and blocks forever.
>
> {code:java}
> "JobScheduler:JMS" #46 [38147] daemon prio=5 os_prio=31 cpu=3.54ms
> elapsed=273.52s tid=0x0000000ac8330800 nid=38147 waiting on condition
> [0x0000000171df6000]
> java.lang.Thread.State: WAITING (parking)
> at jdk.internal.misc.Unsafe.park([email protected]/Native Method)
> - parking to wait for <0x0000000343ac3e80> (a
> java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync)
> at
> java.util.concurrent.locks.LockSupport.park([email protected]/LockSupport.java:223)
> at
> java.util.concurrent.locks.AbstractQueuedLongSynchronizer.acquire([email protected]/AbstractQueuedLongSynchronizer.java:410)
> at
> java.util.concurrent.locks.AbstractQueuedLongSynchronizer.acquire([email protected]/AbstractQueuedLongSynchronizer.java:650)
> at
> java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.lock([email protected]/ReentrantReadWriteLock.java:966)
> at
> org.apache.activemq.store.kahadb.scheduler.JobSchedulerStoreImpl$8.visit(JobSchedulerStoreImpl.java:684)
> at
> org.apache.activemq.store.kahadb.data.KahaAddScheduledJobCommand.visit(KahaAddScheduledJobCommand.java:283)
> at
> org.apache.activemq.store.kahadb.scheduler.JobSchedulerStoreImpl.process(JobSchedulerStoreImpl.java:679)
> at
> org.apache.activemq.store.kahadb.AbstractKahaDBStore.store(AbstractKahaDBStore.java:495)
> at
> org.apache.activemq.store.kahadb.AbstractKahaDBStore.store(AbstractKahaDBStore.java:403)
> at
> org.apache.activemq.store.kahadb.scheduler.JobSchedulerImpl.doSchedule(JobSchedulerImpl.java:252)
> at
> org.apache.activemq.store.kahadb.scheduler.JobSchedulerImpl.schedule(JobSchedulerImpl.java:100)
> at
> org.apache.activemq.store.kahadb.scheduler.JobSchedulerImpl.mainLoop(JobSchedulerImpl.java:782)
> at
> org.apache.activemq.store.kahadb.scheduler.JobSchedulerImpl.run(JobSchedulerImpl.java:699)
> at java.lang.Thread.runWith([email protected]/Thread.java:1487)
> at java.lang.Thread.run([email protected]/Thread.java:1474)
> "ActiveMQ Journal Checkpoint Worker" #43 [38915] daemon prio=5 os_prio=31
> cpu=4.77ms elapsed=273.69s tid=0x0000000ac82f5000 nid=38915 waiting on
> condition [0x00000001719de000]
> java.lang.Thread.State: WAITING (parking)
> at jdk.internal.misc.Unsafe.park([email protected]/Native Method)
> - parking to wait for <0x0000000343ac3e80> (a
> java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync)
> at
> java.util.concurrent.locks.LockSupport.park([email protected]/LockSupport.java:223)
> at
> java.util.concurrent.locks.AbstractQueuedLongSynchronizer.acquire([email protected]/AbstractQueuedLongSynchronizer.java:410)
> at
> java.util.concurrent.locks.AbstractQueuedLongSynchronizer.acquire([email protected]/AbstractQueuedLongSynchronizer.java:650)
> at
> java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.lock([email protected]/ReentrantReadWriteLock.java:966)
> at
> org.apache.activemq.store.kahadb.AbstractKahaDBStore.checkpointCleanup(AbstractKahaDBStore.java:739)
> at
> org.apache.activemq.store.kahadb.AbstractKahaDBStore$2.run(AbstractKahaDBStore.java:707)
> {code}
>
>
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