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Message-ID:	<2E7F82FAC1FCD2118E1500A024B3BF907DED3B@exchange.mmp.plzen-city.cz>
From:	Horak Daniel <horak AT mmp DOT plzen-city DOT cz>
To:	"'pgsql-hackers AT postgreSQL DOT org'" <pgsql-hackers AT postgreSQL DOT org>
Cc:	"'cygwin AT sourceware DOT cygnus DOT com'" <cygwin AT sourceware DOT cygnus DOT com>,
	"'Joost Kraaijeveld'" <JKraaijeveld AT askesis DOT nl>
Subject:	backend freezeing on win32 fixed (I hope ;-) )
Date:	Mon, 16 Aug 1999 11:35:54 +0200
MIME-Version:	1.0
X-Mailer:	Internet Mail Service (5.5.2448.0)

Hi,

I think I have fixed the freezing of the postgres backend on Windows NT. Now
it survives 5 regression test in a cycle with some concurrent connections
during running the tests.

Where the problem was (manual backtrace):
- InitPostgres() (utils/init/postinit.c)
- InitProcess() (storage/lmgr/proc.c)
- IpcSemaphoreCreate() (storage/ipc/ipc.c)
- semget() (now in libcygipc - sem.c)
- sem_connect() (sem.c)
- WaitForSingleObject() (win32 system call)
- freezing....

It have looked like a problem with initializing the same semaphore for
second time (they are "preinitialized" for performance reasons in
InitProcGlobal() in storage/lmgr/proc.c)

The fix (made for v6.5.1) is here:
-------------------------------
--- src/backend/storage/lmgr/proc.c.old	Sat Aug 14 16:50:19 1999
+++ src/backend/storage/lmgr/proc.c	Sat Aug 14 16:50:52 1999
@@ -160,6 +160,7 @@
 		 * Pre-create the semaphores for the first maxBackends
processes,
 		 * unless we are running as a standalone backend.
 		 */
+#ifndef __CYGWIN__
 		if (key != PrivateIPCKey)
 		{
 			for (i = 0;
@@ -180,6 +181,7 @@
 				ProcGlobal->freeSemMap[i] = (1 <<
PROC_NSEMS_PER_SET);
 			}
 		}
+#endif /* __CYGWIN__ */
 	}
 }
------------------------------- 

				Dan

PS: I have packed the tree after "make install" for 6.5.1 with the patch
above, so it is a "binary distribution".

----------------------------------------------
Daniel Horak
network and system administrator
e-mail: horak AT mmp DOT plzen-city DOT cz
privat e-mail: dan DOT horak AT email DOT cz ICQ:36448176
----------------------------------------------

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