Andres Freund <and...@anarazel.de> writes: > On 2019-05-10 11:38:57 -0400, Tom Lane wrote: >> I am wondering if, somehow, the stack depth limit seen by the postmaster >> sometimes doesn't apply to its children. That would be pretty wacko >> kernel behavior, especially if it's only intermittently true. >> But we're running out of other explanations.
> I wonder if this is a SIGSEGV that actually signals an OOM > situation. Linux, if it can't actually extend the stack on-demand due to > OOM, sends a SIGSEGV. The signal has that information, but > unfortunately the buildfarm code doesn't print it. p $_siginfo would > show us some of that... > Mark, how tight is the memory on that machine? Does dmesg have any other > information (often segfaults are logged by the kernel with the code > IIRC). It does sort of smell like a resource exhaustion problem, especially if all these buildfarm animals are VMs running on the same underlying platform. But why would that manifest as "you can't have a measly two megabytes of stack" and not as any other sort of OOM symptom? Mark, if you don't mind modding your local copies of the buildfarm script, I think what Andres is asking for is a pretty trivial addition in PGBuild/Utils.pm's sub get_stack_trace: my $cmdfile = "./gdbcmd"; my $handle; open($handle, '>', $cmdfile) || die "opening $cmdfile: $!"; print $handle "bt\n"; + print $handle "p $_siginfo\n"; close($handle); regards, tom lane