On Mon, Feb 11, 2019 at 09:45:07AM +1100, Thomas Munro wrote: > Ouch. Yeah, that'd do it and matches the evidence. With this change, > I couldn't reproduce the problem after 90 minutes with a test case > that otherwise hits it within a couple of minutes. ... > Note that this patch addresses the error "dsa_allocate could not find > %zu free pages". (The error "dsa_area could not attach to segment" is > something else and apparently rarer.)
"could not attach" is the error reported early this morning while stress-testing this patch with queued_alters queries in loops, so that's consistent with your understanding. And I guess it preceded getting stuck on lock; although I don't how long between the first happened and the second, I'm guess not long and perhaps immedidately; since the rest of the processes were all stuck as in bug#15585 rather than ERRORing once every few minutes. I mentioned that "could not attach to segment" occurs in leader either/or parallel worker. And most of the time causes an ERROR only, and doesn't wedge all future parallel workers. Maybe bug#15585 "wedged" state maybe only occurs after some pattern of leader+worker failures (?) I've just triggered bug#15585 again, but if there's a pattern, I don't see it. Please let me know whether you're able to reproduce the "not attach" bug using simultaneous loops around the queued_alters query; it's easy here. Justin
