Re: [PATCHES] Possible explanation for Win32 stats regression
От | Andrew Dunstan |
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Тема | Re: [PATCHES] Possible explanation for Win32 stats regression |
Дата | |
Msg-id | 44CB6ED1.4040803@dunslane.net обсуждение исходный текст |
Ответ на | Re: Possible explanation for Win32 stats regression test ("korryd@enterprisedb.com" <korryd@enterprisedb.com>) |
Ответы |
Re: [PATCHES] Possible explanation for Win32 stats
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Список | pgsql-hackers |
heh. I was just doing it the way Tom suggested - see attached. With a little more trouble we could also keep track if the listened for events and sometimes save ourselves a second call to WSAEventSelect, but I'm not sure it's worth it. cheers andrew korryd@enterprisedb.com wrote: >> Is anyone working on this? >> >> Tom Lane wrote: >> > korry <korry@appx.com <mailto:korry@appx.com>> writes: >> > > The problem is that, each time you go through >> > > pgwin32_waitforsinglesocket(), you tie the *same* kernel object >> > > (waitevent is static) to each socket. >> > >> > > The fix is pretty simple - just call WSAEventSelect( s, waitevent, 0 ) >> > > after WaitForMultipleObjectsEx() returns. That disassociates the socket >> > > from the Event (it will get re-associated the next time >> > > pgwin32_waitforsingleselect() is called. >> > >> > Hmm. Presumably we don't do this a whole lot (use multiple sockets) or >> > we'd have noticed before. Perhaps better would be to keep an additional >> > static variable saying which socket the event is currently associated >> > to, and only issue the extra WSAEventSelect calls if we need to change >> > it. Or is WSAEventSelect fast enough that it doesn't matter? >> > >> > > Here's a simple patch that fixes the problem (I haven't explored the > performance of this patch compared to Tom's suggestion). > > Index: backend/port/win32/socket.c =================================================================== RCS file: /cvsroot/pgsql/src/backend/port/win32/socket.c,v retrieving revision 1.11 diff -c -r1.11 socket.c *** backend/port/win32/socket.c 5 Mar 2006 15:58:35 -0000 1.11 --- backend/port/win32/socket.c 29 Jul 2006 14:19:23 -0000 *************** *** 106,111 **** --- 106,112 ---- pgwin32_waitforsinglesocket(SOCKET s, int what) { static HANDLE waitevent = INVALID_HANDLE_VALUE; + static SOCKET current_socket = -1; HANDLE events[2]; int r; *************** *** 121,126 **** --- 122,136 ---- ereport(ERROR, (errmsg_internal("Failed to reset socket waiting event: %i", (int) GetLastError()))); + /* + * make sure we don't multiplex this with a different socket + * from a previous call + */ + + if (current_socket != s && current_socket != -1) + WSAEventSelect(current_socket, waitevent, 0); + + current_socket = s; if (WSAEventSelect(s, waitevent, what) == SOCKET_ERROR) {
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