On Fri, Mar 13, 2015 at 7:00 PM, Robert Haas <robertmh...@gmail.com> wrote: > > On Fri, Mar 13, 2015 at 8:59 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: > > We can't directly call DestroyParallelContext() to terminate workers as > > it can so happen that by that time some of the workers are still not > > started. > > That shouldn't be a problem. TerminateBackgroundWorker() not only > kills an existing worker if there is one, but also tells the > postmaster that if it hasn't started the worker yet, it should not > bother. So at the conclusion of the first loop inside > DestroyParallelContext(), every running worker will have received > SIGTERM and no more workers will be started. >
The problem occurs in second loop inside DestroyParallelContext() where it calls WaitForBackgroundWorkerShutdown(). Basically WaitForBackgroundWorkerShutdown() just checks for BGWH_STOPPED status, refer below code in parallel-mode patch: + status = GetBackgroundWorkerPid(handle, &pid); + if (status == BGWH_STOPPED) + return status; So if the status here returned is BGWH_NOT_YET_STARTED, then it will go for WaitLatch and will there forever. I think fix is to check if status is BGWH_STOPPED or BGWH_NOT_YET_STARTED, then just return the status. What do you say? With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
