ITAGAKI Takahiro wrote:
>
> Alvaro Herrera <[EMAIL PROTECTED]> wrote:
>
> > > No, I meant a "while (sleep 1(or 10) and counter < longtime) check for
> > > exit" instead of "sleep longtime".
> >
> > Ah; yes, what I was proposing (or thought about proposing, not sure if I
> > posted it or not) was putting a upper limit of 10 seconds in the sleep
> > (bgwriter sleeps 10 seconds if configured to not do anything). Though
> > 10 seconds may seem like an eternity for systems like the ones Peter was
> > talking about, where there is a script trying to restart the server as
> > soon as the postmaster dies.
>
> Here is a patch for split-sleep of autovacuum_naptime.
>
> There are some other issues in CVS HEAD; We use the calculation
> {autovacuum_naptime * 1000000} in launcher_determine_sleep().
> The result will be corrupted if we set autovacuum_naptime to >2147.
Ugh. How about this patch; this avoids the overflow issue altogether.
I am not sure that this works on Win32 but it seems we are already using
struct timeval elsewhere, so I don't see why it wouldn't work.
> In another place, we use {autovacuum_naptime * 1000}, so we should
> set the upper bound to INT_MAX/1000 instead of INT_MAX.
> Incidentally, we've already had the same protections for
> log_min_duration_statement and log_autovacuum.
Hmm, yes, the naptime should have an upper bound of INT_MAX/1000. It
doesn't seem worth the trouble of changing those places, when we know
that such a high value of naptime is uselessly high.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
Index: src/backend/postmaster/autovacuum.c
===================================================================
RCS file: /home/alvherre/Code/cvs/pgsql/src/backend/postmaster/autovacuum.c,v
retrieving revision 1.49
diff -c -p -r1.49 autovacuum.c
*** src/backend/postmaster/autovacuum.c 8 Jun 2007 21:21:28 -0000 1.49
--- src/backend/postmaster/autovacuum.c 13 Jun 2007 17:27:39 -0000
***************
*** 18,23 ****
--- 18,24 ----
#include <signal.h>
#include <sys/types.h>
+ #include <sys/time.h>
#include <time.h>
#include <unistd.h>
*************** int autovacuum_vac_cost_limit;
*** 73,78 ****
--- 74,83 ----
int Log_autovacuum = -1;
+
+ /* maximum sleep duration in the launcher */
+ #define AV_SLEEP_QUANTUM 10
+
/* Flags to tell if we are in an autovacuum process */
static bool am_autovacuum_launcher = false;
static bool am_autovacuum_worker = false;
*************** NON_EXEC_STATIC void AutoVacWorkerMain(i
*** 197,203 ****
NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]);
static Oid do_start_worker(void);
! static uint64 launcher_determine_sleep(bool canlaunch, bool recursing);
static void launch_worker(TimestampTz now);
static List *get_database_list(void);
static void rebuild_database_list(Oid newdb);
--- 202,209 ----
NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]);
static Oid do_start_worker(void);
! static void launcher_determine_sleep(bool canlaunch, bool recursing,
! struct timeval *nap);
static void launch_worker(TimestampTz now);
static List *get_database_list(void);
static void rebuild_database_list(Oid newdb);
*************** AutoVacLauncherMain(int argc, char *argv
*** 487,493 ****
for (;;)
{
! uint64 micros;
bool can_launch;
TimestampTz current_time = 0;
--- 493,499 ----
for (;;)
{
! struct timeval nap;
bool can_launch;
TimestampTz current_time = 0;
*************** AutoVacLauncherMain(int argc, char *argv
*** 498,508 ****
if (!PostmasterIsAlive(true))
exit(1);
! micros = launcher_determine_sleep(AutoVacuumShmem->av_freeWorkers !=
! INVALID_OFFSET, false);
! /* Sleep for a while according to schedule */
! pg_usleep(micros);
/* the normal shutdown case */
if (avlauncher_shutdown_request)
--- 504,542 ----
if (!PostmasterIsAlive(true))
exit(1);
! launcher_determine_sleep(AutoVacuumShmem->av_freeWorkers !=
! INVALID_OFFSET, false, &nap);
!
! /*
! * Sleep for a while according to schedule. We only sleep in
! * AV_SLEEP_QUANTUM sec intervals, in order to promptly notice
! * postmaster death.
! */
! while (nap.tv_sec > 0 || nap.tv_usec > 0)
! {
! uint32 sleeptime;
!
! sleeptime = nap.tv_usec;
! nap.tv_usec = 0;
! if (nap.tv_sec > 0)
! {
! sleeptime += Min(nap.tv_sec, AV_SLEEP_QUANTUM) * 1000000;
! nap.tv_sec -= Min(nap.tv_sec, AV_SLEEP_QUANTUM);
! }
!
! pg_usleep(sleeptime);
!
! /*
! * Emergency bailout if postmaster has died. This is to avoid the
! * necessity for manual cleanup of all postmaster children.
! */
! if (!PostmasterIsAlive(true))
! exit(1);
!
! if (avlauncher_shutdown_request || got_SIGHUP || got_SIGUSR1)
! break;
! }
/* the normal shutdown case */
if (avlauncher_shutdown_request)
*************** AutoVacLauncherMain(int argc, char *argv
*** 647,662 ****
}
/*
! * Determine the time to sleep, in microseconds, based on the database list.
*
* The "canlaunch" parameter indicates whether we can start a worker right now,
! * for example due to the workers being all busy.
*/
! static uint64
! launcher_determine_sleep(bool canlaunch, bool recursing)
{
- long secs;
- int usecs;
Dlelem *elem;
/*
--- 681,695 ----
}
/*
! * Determine the time to sleep, based on the database list.
*
* The "canlaunch" parameter indicates whether we can start a worker right now,
! * for example due to the workers being all busy. If this is false, we will
! * cause a long sleep, which will be interrupted when a worker exits.
*/
! static void
! launcher_determine_sleep(bool canlaunch, bool recursing, struct timeval *nap)
{
Dlelem *elem;
/*
*************** launcher_determine_sleep(bool canlaunch,
*** 667,689 ****
*/
if (!canlaunch)
{
! secs = autovacuum_naptime;
! usecs = 0;
}
else if ((elem = DLGetTail(DatabaseList)) != NULL)
{
avl_dbase *avdb = DLE_VAL(elem);
TimestampTz current_time = GetCurrentTimestamp();
TimestampTz next_wakeup;
next_wakeup = avdb->adl_next_worker;
TimestampDifference(current_time, next_wakeup, &secs, &usecs);
}
else
{
/* list is empty, sleep for whole autovacuum_naptime seconds */
! secs = autovacuum_naptime;
! usecs = 0;
}
/*
--- 700,727 ----
*/
if (!canlaunch)
{
! nap->tv_sec = autovacuum_naptime;
! nap->tv_usec = 0;
}
else if ((elem = DLGetTail(DatabaseList)) != NULL)
{
avl_dbase *avdb = DLE_VAL(elem);
TimestampTz current_time = GetCurrentTimestamp();
TimestampTz next_wakeup;
+ long secs;
+ int usecs;
next_wakeup = avdb->adl_next_worker;
TimestampDifference(current_time, next_wakeup, &secs, &usecs);
+
+ nap->tv_sec = secs;
+ nap->tv_usec = usecs;
}
else
{
/* list is empty, sleep for whole autovacuum_naptime seconds */
! nap->tv_sec = autovacuum_naptime;
! nap->tv_usec = 0;
}
/*
*************** launcher_determine_sleep(bool canlaunch,
*** 696,715 ****
* We only recurse once. rebuild_database_list should always return times
* in the future, but it seems best not to trust too much on that.
*/
! if (secs == 0L && usecs == 0 && !recursing)
{
rebuild_database_list(InvalidOid);
! return launcher_determine_sleep(canlaunch, true);
}
/* 100ms is the smallest time we'll allow the launcher to sleep */
! if (secs <= 0L && usecs <= 100000)
{
! secs = 0L;
! usecs = 100000; /* 100 ms */
}
-
- return secs * 1000000 + usecs;
}
/*
--- 734,752 ----
* We only recurse once. rebuild_database_list should always return times
* in the future, but it seems best not to trust too much on that.
*/
! if (nap->tv_sec == 0L && nap->tv_usec == 0 && !recursing)
{
rebuild_database_list(InvalidOid);
! launcher_determine_sleep(canlaunch, true, nap);
! return;
}
/* 100ms is the smallest time we'll allow the launcher to sleep */
! if (nap->tv_sec <= 0L && nap->tv_usec <= 100000)
{
! nap->tv_sec = 0L;
! nap->tv_usec = 100000; /* 100 ms */
}
}
/*
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