Lionel Bouton wrote:
>
> The following bug has been logged online:
>
> Bug reference: 1588
> Logged by: Lionel Bouton
> Email address: [EMAIL PROTECTED]
> PostgreSQL version: 8.0.1
> Operating system: Linux 2.6, glibc 2.3.4
> Description: pg_autovacuum sleep parameter overflow
> Details:
>
> pg_autovacuum doesn't sleep when the -s parameter is set above 2147
> (PostgreSQL then is under constant stress), seems like a 32-bit signed
> integer overflow (the time in µs then gets past 2^31-1) somewhere.
>
> This worked with 7.4.6 (at least with -s 3600).
Yes, this is a bug. Right now, pg_autovacuum uses pg_usleep(), which
accepts a 'long' value representing the number of microseconds to sleep.
Because long is 32-bits on many platforms, it overflows around 2 billion
microseconds, which is 2147 seconds. The comment in pg_usleep()
verifies it:
* On machines where "long" is 32 bits, the maximum delay is ~2000 seconds.
Here is a proposed patch that will fix it. There is no reason to use
pg_usleep in pg_autovacuum in this area, so we just use sleep(). We
don't need micro-second accuracy, and we don't need Win32 to handle
signals that arrive during the sleep.
However, I am now wondering if we should change pg_usleep() to take a
double rather than long. This would avoid such problems in the future
in other places in our code.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
Index: contrib/pg_autovacuum/pg_autovacuum.c
===================================================================
RCS file: /cvsroot/pgsql/contrib/pg_autovacuum/pg_autovacuum.c,v
retrieving revision 1.31
diff -c -c -r1.31 pg_autovacuum.c
*** contrib/pg_autovacuum/pg_autovacuum.c 19 Apr 2005 03:35:15 -0000
1.31
--- contrib/pg_autovacuum/pg_autovacuum.c 11 May 2005 14:43:34 -0000
***************
*** 1749,1755 ****
fflush(LOGOUTPUT);
}
! pg_usleep(sleep_secs * 1000000); /* Larger Pause between
outer loops */
gettimeofday(&then, 0); /* Reset time counter */
--- 1749,1764 ----
fflush(LOGOUTPUT);
}
! /* Larger Pause between outer loops */
! /*
! * pg_usleep() is wrong here because its maximum is ~2000
seconds,
! * and we don't need signal interruptability on Win32 here.
! */
! #ifndef WIN32
! sleep(sleep_secs); /* Unix sleep is
seconds */
! #else
! sleep(sleep_secs * 1000); /* Win32 sleep() is
milliseconds */
! #endif
gettimeofday(&then, 0); /* Reset time counter */
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