backend freezeing on win32 fixed (I hope ;-) )

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: 1999-08-16 09:35:54
Message-ID: 2E7F82FAC1FCD2118E1500A024B3BF907DED3B@exchange.mmp.plzen-city.cz
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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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