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authorAlvaro Herrera2009-06-09 16:41:02 +0000
committerAlvaro Herrera2009-06-09 16:41:02 +0000
commitfdb17362ad4ca499651f3f6cacc9e769c7afaf7d (patch)
treeeadc197e331b5cf19d30794561b7322b66941665
parent0065bc020c95f50e54ba060ac2b8749f2927ff8e (diff)
Dynamically set a lower bound on autovacuum nap time so that we don't rebuild
the database list too often. Per bug report from Łukasz Jagiełło and ensuing discussion on pgsql-performance.
-rw-r--r--src/backend/postmaster/autovacuum.c19
1 files changed, 15 insertions, 4 deletions
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index ad7228144f..3bdb12e3b0 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -123,6 +123,8 @@ int Log_autovacuum_min_duration = -1;
/* how long to keep pgstat data in the launcher, in milliseconds */
#define STATS_READ_DELAY 1000
+/* the minimum allowed time between two awakening of the launcher */
+#define MIN_AUTOVAC_SLEEPTIME 100.0 /* milliseconds */
/* Flags to tell if we are in an autovacuum process */
static bool am_autovacuum_launcher = false;
@@ -822,11 +824,11 @@ launcher_determine_sleep(bool canlaunch, bool recursing, struct timeval * nap)
return;
}
- /* 100ms is the smallest time we'll allow the launcher to sleep */
- if (nap->tv_sec <= 0 && nap->tv_usec <= 100000)
+ /* The smallest time we'll allow the launcher to sleep. */
+ if (nap->tv_sec <= 0 && nap->tv_usec <= MIN_AUTOVAC_SLEEPTIME * 1000)
{
nap->tv_sec = 0;
- nap->tv_usec = 100000; /* 100 ms */
+ nap->tv_usec = MIN_AUTOVAC_SLEEPTIME * 1000;
}
}
@@ -997,8 +999,17 @@ rebuild_database_list(Oid newdb)
/* sort the array */
qsort(dbary, nelems, sizeof(avl_dbase), db_comparator);
- /* this is the time interval between databases in the schedule */
+ /*
+ * Determine the time interval between databases in the schedule.
+ * If we see that the configured naptime would take us to sleep times
+ * lower than our min sleep time (which launcher_determine_sleep is
+ * coded not to allow), silently use a larger naptime (but don't touch
+ * the GUC variable).
+ */
millis_increment = 1000.0 * autovacuum_naptime / nelems;
+ if (millis_increment <= MIN_AUTOVAC_SLEEPTIME)
+ millis_increment = MIN_AUTOVAC_SLEEPTIME * 1.1;
+
current_time = GetCurrentTimestamp();
/*