From 2e371183ee8c766d6d166f71060858e14d181220 Mon Sep 17 00:00:00 2001
From: Magnus Hagander <magnus@hagander.net>
Date: Sun, 15 Feb 2009 13:58:18 +0000
Subject: [PATCH] Loop calling CallNamedPipe() several times in case it fails,
since it can be transient failures, causing kill() to not properly send
signals.
Original patch from Steve Marshall, modified by me.
---
src/port/kill.c | 41 ++++++++++++++++++++++++++---------------
1 file changed, 26 insertions(+), 15 deletions(-)
diff --git a/src/port/kill.c b/src/port/kill.c
index ea71f75c3e9..1ec5ee5b783 100644
--- a/src/port/kill.c
+++ b/src/port/kill.c
@@ -9,7 +9,7 @@
* signals that the backend can recognize.
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/port/kill.c,v 1.11 2009/01/01 17:24:04 momjian Exp $
+ * $PostgreSQL: pgsql/src/port/kill.c,v 1.12 2009/02/15 13:58:18 mha Exp $
*
*-------------------------------------------------------------------------
*/
@@ -25,6 +25,7 @@ pgkill(int pid, int sig)
BYTE sigData = sig;
BYTE sigRet = 0;
DWORD bytes;
+ int pipe_tries;
/* we allow signal 0 here, but it will be ignored in pg_queue_signal */
if (sig >= PG_SIGNAL_COUNT || sig < 0)
@@ -39,23 +40,33 @@ pgkill(int pid, int sig)
return -1;
}
snprintf(pipename, sizeof(pipename), "\\\\.\\pipe\\pgsignal_%u", pid);
- if (!CallNamedPipe(pipename, &sigData, 1, &sigRet, 1, &bytes, 1000))
- {
- if (GetLastError() == ERROR_FILE_NOT_FOUND)
- errno = ESRCH;
- else if (GetLastError() == ERROR_ACCESS_DENIED)
- errno = EPERM;
- else
- errno = EINVAL;
- return -1;
- }
- if (bytes != 1 || sigRet != sig)
+
+ /*
+ * Writing data to the named pipe can fail for transient reasons.
+ * Therefore, it is useful to retry if it fails. The maximum number of
+ * calls to make was empirically determined from a 90-hour notification
+ * stress test.
+ */
+ for (pipe_tries = 0; pipe_tries < 3; pipe_tries++)
{
- errno = ESRCH;
- return -1;
+ if (CallNamedPipe(pipename, &sigData, 1, &sigRet, 1, &bytes, 1000))
+ {
+ if (bytes != 1 || sigRet != sig)
+ {
+ errno = ESRCH;
+ return -1;
+ }
+ return 0;
+ }
}
- return 0;
+ if (GetLastError() == ERROR_FILE_NOT_FOUND)
+ errno = ESRCH;
+ else if (GetLastError() == ERROR_ACCESS_DENIED)
+ errno = EPERM;
+ else
+ errno = EINVAL;
+ return -1;
}
#endif
--
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