On Mon, Aug 3, 2009 at 15:47, Nikhil Sontakke<nikhil.sonta...@enterprisedb.com> wrote: > Hi, > >>> >>> >>>> ntdll.dll!NtWaitForMultipleObjects+0xc >>>> kernel32.dll!WaitForMultipleObjectsEx+0x11a >>>> postgres.exe!pgwin32_waitforsinglesocket+0x1ed >>>> postgres.exe!pgwin32_recv+0x90 >>>> postgres.exe!PgstatCollectorMain+0x17f >>>> postgres.exe!SubPostmasterMain+0x33a >>>> postgres.exe!main+0x168 >>>> postgres.exe!__tmainCRTStartup+0x10f >>>> kernel32.dll!BaseProcessStart+0x23 >>> >>> I have seen this problem too. The process seems stuck for no good >>> reason. I wondered at the time if it could be a kernel issue. I >>> remember trying to send some data to the collector to verify whether >>> it'd wake up, but no luck. (I mean I couldn't find a way to do it on >>> Windows). >> >> I have seen this as well, but only in cases where there has been >> broken firewall software or such things involved. I have seen a couple >> of reports from the field though. >> >> Anyway, this really is a should-never-happen thing. As soon as a new >> packet is sent in, WaitForMultipleObjectsEx() should return right >> away. And given that backends regularly send packets over, it >> shouldn't be an issue even if we miss one... >> > > And this fact should lend credence to Alvaro's (as well as mine) > suspicions that it seems to be a Windows kernel issue. > > As a consequence, Magnus I was wondering if having a loop similar to > the WRITE handling of waiting for a fixed timeout in a loop (rather > than an INFINITE call to WaitForMultipleObjectsEx) inside the > pgwin32_waitforsinglesocket() function will help for the READ case > too? I believe Teogor Sigaev had raised a similar concern a while back > about it: > > http://www.nabble.com/-GENERAL--Stats-collector-frozen--td8569977i20.html
Maybe. I'm unsure if it's enough to just try another WaitForSingleObjectEx() on it, or if we need to actually issue a WSARecv() on it as well. Maybe it would be enough to just change the INIFINTE on line 318 of socket.c to a fixed value. That will loop down to WSARecv() which should exit with WSAEWOULDBLOCK which will cause us to do a short sleep and come back. But we'd have to change the limit of 5 somehow then, since in theory we should wait forever. Maybe that outer loop should just be a for(;;), what do you think? From what I understand, none of you have an environment where you can reliably reproduce this? That means it's going to be a PITA to try to figure out if we're actually fixing anything :S -- Magnus Hagander Self: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
