topic Re: AsyncExecutor multiple instances causing deadlock in Alfresco Forum

AsyncExecutor multiple instances causing deadlock

francop — Wed, 11 Jan 2017 14:14:38 GMT

Hi, We are currently experiencing out of memory(OOM) situation in our application. Thread dump shows blocked threads on activiti's AsyncJobExecutor with 2 instances of the same being created concurrently to acquire the jobs, blocking on each other causing deadlock situation. This results in spinning

Re: AsyncExecutor multiple instances causing deadlock

gdharley — Wed, 11 Jan 2017 17:53:12 GMT

Hello Franco,

An interesting problem and certainly not one I have ever come across, which suggests it to be an environmental issue.
The fact that Activiti creates two threads that both monitor the Job Queue (ACT_RU_JOBS) is completely expected and in fact a performance enhancement made around the 5.17 release. Prior to this, a single Job Executor thread was responsible for both async and timer jobs.

The change introduced a second thread, now we have a thread managing async jobs and a second managing timer jobs. Both share the ACT_RU_JOBS table where lock details, retry counts etc are stored.

Likely this has something to do with your Oracle connection pool setup, transaction isolation level or something like that but without a full repro environment I can't really give you much more than that.

Greg

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Re: AsyncExecutor multiple instances causing deadlock

francop — Wed, 11 Jan 2017 19:51:55 GMT

Thanks for the response Greg. I will dig into at our end to see if we can find something.