ActivitiOptimisticLockException and multiple async executors

[tomekzaremba]

Hi,

why ActivitiOptimisticLockException is thrown after serviceTask is completed, not before its execution? During stress tests I can see, that executor which get AOLE done given serviceTask and after that exception is thrown, so task will be executed again?

Why lock is not checked before serviceTask execution? And another question - how I can handle such case to avoid such situations?

[tomekzaremba]

Additionally I enabled DEBUG level and I see such logs:

<code>
dev-8097EBUG [2016-02-22 14:15:59.905] [,org.activiti.engine.impl.db.DbSqlSession,provideTaskExecutor-1,,,,]   insert JobEntity [id=6a5d299d-d966-11e5-80df-ac87a327df39]
dev-8097EBUG [2016-02-22 14:15:59.905] [,org.activiti.engine.impl.db.DbSqlSession,provideTaskExecutor-1,,,,] inserting: JobEntity [id=6a5d299d-d966-11e5-80df-ac87a327df39]
dev-8097EBUG [2016-02-22 14:15:59.905] [,o.a.e.i.p.entity.JobEntity.insertMessage,provideTaskExecutor-1,,,,] ==> Parameters: 6a5d299d-d966-11e5-80df-ac87a327df39(String), null, null, true(Boolean), cafab7c5-d95e-11e5-890a-ac87a327df39(String), 5cca19f3-d95e-11e5-890a-ac87a327df39(String), exchange-processing:18:a4737b75-d92f-11e5-b0f5-ac87a327df39(String), 2016-02-22 14:20:59.905(Timestamp), 3(Integer), null, null, async-continuation(String), null, (String)
dev-8097EBUG [2016-02-22 14:21:45.417] [,o.a.engine.impl.cmd.LockExclusiveJobCmd ,provideTaskExecutor-1,,,,] Executing lock exclusive job 6a5d299d-d966-11e5-80df-ac87a327df39 cafab7c5-d95e-11e5-890a-ac87a327df39
dev-8097EBUG [2016-02-22 14:21:45.418] [,o.a.engine.impl.cmd.ExecuteAsyncJobCmd  ,provideTaskExecutor-1,,,,] Executing async job 6a5d299d-d966-11e5-80df-ac87a327df39
dev-8097EBUG [2016-02-22 14:21:50.884] [B099000688,org.activiti.engine.impl.db.DbSqlSession,provideTaskExecutor-1,,,729480,1000764210]   delete JobEntity [id=6a5d299d-d966-11e5-80df-ac87a327df39]
dev-8097EBUG [2016-02-22 14:21:50.887] [B099000688,org.activiti.engine.impl.db.DbSqlSession,provideTaskExecutor-1,,,729480,1000764210] executing: delete JobEntity [id=6a5d299d-d966-11e5-80df-ac87a327df39]
dev-8097EBUG [2016-02-22 14:21:50.887] [B099000688,o.a.e.i.p.entity.JobEntity.deleteMessage,provideTaskExecutor-1,,,729480,1000764210] ==> Parameters: 6a5d299d-d966-11e5-80df-ac87a327df39(String), 1(Integer)
dev-8097EBUG [2016-02-22 14:21:50.887] [B099000688,o.a.e.impl.interceptor.CommandContext   ,provideTaskExecutor-1,,,729480,1000764210] Optimistic locking exception : org.activiti.engine.ActivitiOptimisticLockingException: JobEntity [id=6a5d299d-d966-11e5-80df-ac87a327df39] was updated by another transaction concurrently
dev-8097EBUG [2016-02-22 14:21:50.888] [B099000688,o.a.e.i.p.entity.JobEntity.selectJob    ,provideTaskExecutor-1,,,729480,1000764210] ==> Parameters: 6a5d299d-d966-11e5-80df-ac87a327df39(String)
dev-8097EBUG [2016-02-22 14:21:50.889] [B099000688,org.activiti.engine.impl.db.DbSqlSession,provideTaskExecutor-1,,,729480,1000764210]   update JobEntity [id=6a5d299d-d966-11e5-80df-ac87a327df39]
dev-8097EBUG [2016-02-22 14:21:50.889] [B099000688,org.activiti.engine.impl.db.DbSqlSession,provideTaskExecutor-1,,,729480,1000764210] updating: JobEntity [id=6a5d299d-d966-11e5-80df-ac87a327df39]
dev-8097EBUG [2016-02-22 14:21:50.889] [B099000688,o.a.e.i.p.entity.JobEntity.updateMessage,provideTaskExecutor-1,,,729480,1000764210] ==> Parameters: 3(Integer), null, null, 2(Integer), 3b911190-d967-11e5-80df-ac87a327df39(String), JobEntity [id=6a5d299d-d966-11e5-80df-ac87a327df39] was updated by another transaction concurrently(String), 2016-02-22 14:26:50.889(Timestamp), 6a5d299d-d966-11e5-80df-ac87a327df39(String), 2(Integer)
dev-8097EBUG [2016-02-22 14:21:50.890] [B099000688,p.p.e.ComLoggingExecuteAsyncRunnable    ,provideTaskExecutor-1,,,729480,1000764210] Optimistic locking exception during job: 6a5d299d-d966-11e5-80df-ac87a327df39 / executionId: cafab7c5-d95e-11e5-890a-ac87a327df39 / processInstance: 5cca19f3-d95e-11e5-890a-ac87a327df39
dev-8097EBUG [2016-02-22 14:21:50.890] [B099000688,o.a.e.impl.cmd.UnlockExclusiveJobCmd    ,provideTaskExecutor-1,,,729480,1000764210] Unlocking exclusive job 6a5d299d-d966-11e5-80df-ac87a327df39
</code>

I don't see any additional updates, so why AOLE is thrown? JobEntity is executed only on one app instance as you can see from log file name.

[jbarrez]

Optimistic locking on itself is not a problem. If you have multiple executors, it is even expected, as multiple executors are battling for the same jobs. Nothing to worry about.. (see other thread where I replied too)