From ebfc56d3fb41d914c799555a1f4c9d1a72379e9f Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sun, 23 May 2004 03:50:45 +0000 Subject: Handle impending sinval queue overflow by means of a separate signal (SIGUSR1, which we have not been using recently) instead of piggybacking on SIGUSR2-driven NOTIFY processing. This has several good results: the processing needed to drain the sinval queue is a lot less than the processing needed to answer a NOTIFY; there's less contention since we don't have a bunch of backends all trying to acquire exclusive lock on pg_listener; backends that are sitting inside a transaction block can still drain the queue, whereas NOTIFY processing can't run if there's an open transaction block. (This last is a fairly serious issue that I don't think we ever recognized before --- with clients like JDBC that tend to sit with open transaction blocks, the sinval queue draining mechanism never really worked as intended, probably resulting in a lot of useless cache-reset overhead.) This is the last of several proposed changes in response to Philip Warner's recent report of sinval-induced performance problems. --- src/backend/tcop/postgres.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) (limited to 'src/backend/tcop/postgres.c') diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index d097612ba30..604dd9819eb 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.413 2004/05/21 05:07:58 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.414 2004/05/23 03:50:45 tgl Exp $ * * NOTES * this is the "main" module of the postgres backend and @@ -52,6 +52,7 @@ #include "storage/ipc.h" #include "storage/pg_shmem.h" #include "storage/proc.h" +#include "storage/sinval.h" #include "tcop/fastpath.h" #include "tcop/pquery.h" #include "tcop/tcopprot.h" @@ -1899,6 +1900,7 @@ die(SIGNAL_ARGS) /* until we are done getting ready for it */ InterruptHoldoffCount++; DisableNotifyInterrupt(); + DisableCatchupInterrupt(); /* Make sure CheckDeadLock won't run while shutting down... */ LockWaitCancel(); InterruptHoldoffCount--; @@ -1955,6 +1957,7 @@ StatementCancelHandler(SIGNAL_ARGS) if (LockWaitCancel()) { DisableNotifyInterrupt(); + DisableCatchupInterrupt(); InterruptHoldoffCount--; ProcessInterrupts(); } @@ -2006,6 +2009,7 @@ ProcessInterrupts(void) QueryCancelPending = false; /* ProcDie trumps QueryCancel */ ImmediateInterruptOK = false; /* not idle anymore */ DisableNotifyInterrupt(); + DisableCatchupInterrupt(); ereport(FATAL, (errcode(ERRCODE_ADMIN_SHUTDOWN), errmsg("terminating connection due to administrator command"))); @@ -2015,6 +2019,7 @@ ProcessInterrupts(void) QueryCancelPending = false; ImmediateInterruptOK = false; /* not idle anymore */ DisableNotifyInterrupt(); + DisableCatchupInterrupt(); ereport(ERROR, (errcode(ERRCODE_QUERY_CANCELED), errmsg("canceling query due to user request"))); @@ -2595,9 +2600,8 @@ PostgresMain(int argc, char *argv[], const char *username) * midst of output during who-knows-what operation... */ pqsignal(SIGPIPE, SIG_IGN); - pqsignal(SIGUSR1, SIG_IGN); /* this signal available for use */ - - pqsignal(SIGUSR2, Async_NotifyHandler); /* flush also sinval cache */ + pqsignal(SIGUSR1, CatchupInterruptHandler); + pqsignal(SIGUSR2, NotifyInterruptHandler); pqsignal(SIGFPE, FloatExceptionHandler); /* @@ -2761,6 +2765,7 @@ PostgresMain(int argc, char *argv[], const char *username) disable_sig_alarm(true); QueryCancelPending = false; /* again in case timeout occurred */ DisableNotifyInterrupt(); + DisableCatchupInterrupt(); debug_query_string = NULL; /* @@ -2879,6 +2884,7 @@ PostgresMain(int argc, char *argv[], const char *username) * signal */ EnableNotifyInterrupt(); + EnableCatchupInterrupt(); /* Allow "die" interrupt to be processed while waiting */ ImmediateInterruptOK = true; @@ -2901,6 +2907,7 @@ PostgresMain(int argc, char *argv[], const char *username) QueryCancelPending = false; /* forget any CANCEL signal */ DisableNotifyInterrupt(); + DisableCatchupInterrupt(); /* * (5) check for any other interesting events that happened while -- cgit v1.2.3