On Wed, Jun 7, 2017 at 12:37 AM, Robert Haas <robertmh...@gmail.com> wrote: > On Tue, Jun 6, 2017 at 2:21 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >>> One thought is that the only places where shm_mq_set_sender() should >>> be getting invoked during the main regression tests are >>> ParallelWorkerMain() and ExecParallelGetReceiver, and both of those >>> places using ParallelWorkerNumber to figure out what address to pass. >>> So if ParallelWorkerNumber were getting set to the same value in two >>> different parallel workers - e.g. because the postmaster went nuts and >>> launched two processes instead of only one - or if >>> ParallelWorkerNumber were not getting initialized at all or were >>> getting initialized to some completely bogus value, it could cause >>> this symptom. >> >> Hmm. With some generous assumptions it'd be possible to think that >> aa1351f1eec4adae39be59ce9a21410f9dd42118 triggered this. That commit was >> present in 20 successful lorikeet runs before the first of these failures, >> which is a bit more than the MTBF after that, but not a huge amount more. >> >> That commit in itself looks innocent enough, but could it have exposed >> some latent bug in bgworker launching? > > Hmm, that's a really interesting idea, but I can't quite put together > a plausible theory around it. I mean, it seems like that commit could > make launching bgworkers faster, which could conceivably tickle some > heretofore-latent timing-related bug. But it wouldn't, IIUC, make the > first worker start any faster than before - it would just make them > more closely-spaced thereafter, and it's not very obvious how that > would cause a problem. > > Another idea is that the commit in question is managing to corrupt > BackgroundWorkerList somehow. >
I don't think so because this problem has been reported previously as well [1][2] even before the commit in question. [1] - https://www.postgresql.org/message-id/1ce5a19f-3b1d-bb1c-4561-0158176f65f1%40dunslane.net [2] - https://www.postgresql.org/message-id/25861.1472215822%40sss.pgh.pa.us -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
