Hi, On 2017-11-20 10:13:57 -0800, David Pacheco wrote: > I expect what happened is that the syslogger process attempted to allocate > memory, failed because the system was low, and explicitly exited. That's > consistent with an exited process, no core file generated, and the "FATAL" > "out > of memory" entries in the log I posted. Well unfortunately we're presumably not going to see output from syslogger's death itself, chicken and egg etc. > Tom Lane wrote: > > Hm, so that's another angle David didn't report on: is it possible that > > his workload could have resulted in a very large volume of incomplete > > in-progress log messages? > > Yes. I mentioned in my Nov 6 mail that large log messages over a > short period appear to have been a major contributing factor: So it's actually quite possible that syslogger did use a fair amount of memory. Could you show its memory usage, just via ps? > This is a critical point. As far as I can tell, all that's necessary > for this deadlock to occur is: > > - the syslogger is unable to make forward progress (e.g., because it > segfaulted) This specific case I don't care that much about, but ... > - enough other processes write to the pipe that it fills up before the > postmaster can restart the syslogger > - the postmaster attempts to write to the log as part of any of its signal > handling operations > > It seems to me that the same thing can happen if there were a bug in the > syslogger that resulted in a segfault around the same time that the > postmaster > attempted to start an autovacuum worker, for example (if there was also > reasonably high log traffic). Greetings, Andres Freund
