Skip to content

Commit db0f6ca

Browse files
robertmhaasrobertmhaas
committed
Remove set_latch_on_sigusr1 flag.
This flag has proven to be a recipe for bugs, and it doesn't seem like it can really buy anything in terms of performance. So let's just *always* set the process latch when we receive SIGUSR1 instead of trying to do it only when needed. Per my recent proposal on pgsql-hackers.
1 parent b7aac36 commit db0f6ca

File tree

6 files changed

+86
-153
lines changed

6 files changed

+86
-153
lines changed

‎src/backend/postmaster/bgworker.c

Lines changed: 27 additions & 55 deletions
Original file line numberDiff line numberDiff line change
@@ -954,45 +954,31 @@ WaitForBackgroundWorkerStartup(BackgroundWorkerHandle *handle, pid_t *pidp)
954954
{
955955
BgwHandleStatus status;
956956
int rc;
957-
bool save_set_latch_on_sigusr1;
958957

959-
save_set_latch_on_sigusr1 = set_latch_on_sigusr1;
960-
set_latch_on_sigusr1 = true;
961-
962-
PG_TRY();
958+
for (;;)
963959
{
964-
for (;;)
965-
{
966-
pid_t pid;
960+
pid_t pid;
967961

968-
CHECK_FOR_INTERRUPTS();
962+
CHECK_FOR_INTERRUPTS();
969963

970-
status = GetBackgroundWorkerPid(handle, &pid);
971-
if (status == BGWH_STARTED)
972-
*pidp = pid;
973-
if (status != BGWH_NOT_YET_STARTED)
974-
break;
975-
976-
rc = WaitLatch(MyLatch,
977-
WL_LATCH_SET | WL_POSTMASTER_DEATH, 0);
964+
status = GetBackgroundWorkerPid(handle, &pid);
965+
if (status == BGWH_STARTED)
966+
*pidp = pid;
967+
if (status != BGWH_NOT_YET_STARTED)
968+
break;
978969

979-
if (rc & WL_POSTMASTER_DEATH)
980-
{
981-
status = BGWH_POSTMASTER_DIED;
982-
break;
983-
}
970+
rc = WaitLatch(MyLatch,
971+
WL_LATCH_SET | WL_POSTMASTER_DEATH, 0);
984972

985-
ResetLatch(MyLatch);
973+
if (rc & WL_POSTMASTER_DEATH)
974+
{
975+
status = BGWH_POSTMASTER_DIED;
976+
break;
986977
}
978+
979+
ResetLatch(MyLatch);
987980
}
988-
PG_CATCH();
989-
{
990-
set_latch_on_sigusr1 = save_set_latch_on_sigusr1;
991-
PG_RE_THROW();
992-
}
993-
PG_END_TRY();
994981

995-
set_latch_on_sigusr1 = save_set_latch_on_sigusr1;
996982
return status;
997983
}
998984

@@ -1009,40 +995,26 @@ WaitForBackgroundWorkerShutdown(BackgroundWorkerHandle *handle)
1009995
{
1010996
BgwHandleStatus status;
1011997
int rc;
1012-
bool save_set_latch_on_sigusr1;
1013-
1014-
save_set_latch_on_sigusr1 = set_latch_on_sigusr1;
1015-
set_latch_on_sigusr1 = true;
1016998

1017-
PG_TRY();
999+
for (;;)
10181000
{
1019-
for (;;)
1020-
{
1021-
pid_t pid;
1001+
pid_t pid;
10221002

1023-
CHECK_FOR_INTERRUPTS();
1003+
CHECK_FOR_INTERRUPTS();
10241004

1025-
status = GetBackgroundWorkerPid(handle, &pid);
1026-
if (status == BGWH_STOPPED)
1027-
return status;
1005+
status = GetBackgroundWorkerPid(handle, &pid);
1006+
if (status == BGWH_STOPPED)
1007+
return status;
10281008

1029-
rc = WaitLatch(&MyProc->procLatch,
1030-
WL_LATCH_SET | WL_POSTMASTER_DEATH, 0);
1009+
rc = WaitLatch(&MyProc->procLatch,
1010+
WL_LATCH_SET | WL_POSTMASTER_DEATH, 0);
10311011

1032-
if (rc & WL_POSTMASTER_DEATH)
1033-
return BGWH_POSTMASTER_DIED;
1012+
if (rc & WL_POSTMASTER_DEATH)
1013+
return BGWH_POSTMASTER_DIED;
10341014

1035-
ResetLatch(&MyProc->procLatch);
1036-
}
1037-
}
1038-
PG_CATCH();
1039-
{
1040-
set_latch_on_sigusr1 = save_set_latch_on_sigusr1;
1041-
PG_RE_THROW();
1015+
ResetLatch(&MyProc->procLatch);
10421016
}
1043-
PG_END_TRY();
10441017

1045-
set_latch_on_sigusr1 = save_set_latch_on_sigusr1;
10461018
return status;
10471019
}
10481020

‎src/backend/storage/ipc/procsignal.c

Lines changed: 1 addition & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -59,14 +59,6 @@ typedef struct
5959
*/
6060
#define NumProcSignalSlots (MaxBackends + NUM_AUXPROCTYPES)
6161

62-
/*
63-
* If this flag is set, the process latch will be set whenever SIGUSR1
64-
* is received. This is useful when waiting for a signal from the postmaster.
65-
* Spurious wakeups must be expected. Make sure that the flag is cleared
66-
* in the error path.
67-
*/
68-
bool set_latch_on_sigusr1;
69-
7062
static ProcSignalSlot *ProcSignalSlots = NULL;
7163
static volatile ProcSignalSlot *MyProcSignalSlot = NULL;
7264

@@ -296,8 +288,7 @@ procsignal_sigusr1_handler(SIGNAL_ARGS)
296288
if (CheckProcSignal(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN))
297289
RecoveryConflictInterrupt(PROCSIG_RECOVERY_CONFLICT_BUFFERPIN);
298290

299-
if (set_latch_on_sigusr1)
300-
SetLatch(MyLatch);
291+
SetLatch(MyLatch);
301292

302293
latch_sigusr1_handler();
303294

‎src/backend/storage/ipc/shm_mq.c

Lines changed: 31 additions & 45 deletions
Original file line numberDiff line numberDiff line change
@@ -962,63 +962,49 @@ static bool
962962
shm_mq_wait_internal(volatile shm_mq *mq, PGPROC *volatile * ptr,
963963
BackgroundWorkerHandle *handle)
964964
{
965-
bool save_set_latch_on_sigusr1;
966965
bool result = false;
967966

968-
save_set_latch_on_sigusr1 = set_latch_on_sigusr1;
969-
if (handle != NULL)
970-
set_latch_on_sigusr1 = true;
971-
972-
PG_TRY();
967+
for (;;)
973968
{
974-
for (;;)
969+
BgwHandleStatus status;
970+
pid_t pid;
971+
bool detached;
972+
973+
/* Acquire the lock just long enough to check the pointer. */
974+
SpinLockAcquire(&mq->mq_mutex);
975+
detached = mq->mq_detached;
976+
result = (*ptr != NULL);
977+
SpinLockRelease(&mq->mq_mutex);
978+
979+
/* Fail if detached; else succeed if initialized. */
980+
if (detached)
981+
{
982+
result = false;
983+
break;
984+
}
985+
if (result)
986+
break;
987+
988+
if (handle != NULL)
975989
{
976-
BgwHandleStatus status;
977-
pid_t pid;
978-
bool detached;
979-
980-
/* Acquire the lock just long enough to check the pointer. */
981-
SpinLockAcquire(&mq->mq_mutex);
982-
detached = mq->mq_detached;
983-
result = (*ptr != NULL);
984-
SpinLockRelease(&mq->mq_mutex);
985-
986-
/* Fail if detached; else succeed if initialized. */
987-
if (detached)
990+
/* Check for unexpected worker death. */
991+
status = GetBackgroundWorkerPid(handle, &pid);
992+
if (status != BGWH_STARTED && status != BGWH_NOT_YET_STARTED)
988993
{
989994
result = false;
990995
break;
991996
}
992-
if (result)
993-
break;
994-
995-
if (handle != NULL)
996-
{
997-
/* Check for unexpected worker death. */
998-
status = GetBackgroundWorkerPid(handle, &pid);
999-
if (status != BGWH_STARTED && status != BGWH_NOT_YET_STARTED)
1000-
{
1001-
result = false;
1002-
break;
1003-
}
1004-
}
997+
}
1005998

1006-
/* Wait to be signalled. */
1007-
WaitLatch(MyLatch, WL_LATCH_SET, 0);
999+
/* Wait to be signalled. */
1000+
WaitLatch(MyLatch, WL_LATCH_SET, 0);
10081001

1009-
/* An interrupt may have occurred while we were waiting. */
1010-
CHECK_FOR_INTERRUPTS();
1002+
/* An interrupt may have occurred while we were waiting. */
1003+
CHECK_FOR_INTERRUPTS();
10111004

1012-
/* Reset the latch so we don't spin. */
1013-
ResetLatch(MyLatch);
1014-
}
1015-
}
1016-
PG_CATCH();
1017-
{
1018-
set_latch_on_sigusr1 = save_set_latch_on_sigusr1;
1019-
PG_RE_THROW();
1005+
/* Reset the latch so we don't spin. */
1006+
ResetLatch(MyLatch);
10201007
}
1021-
PG_END_TRY();
10221008

10231009
return result;
10241010
}

‎src/backend/tcop/postgres.c

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -2825,9 +2825,7 @@ RecoveryConflictInterrupt(ProcSignalReason reason)
28252825
/*
28262826
* Set the process latch. This function essentially emulates signal
28272827
* handlers like die() and StatementCancelHandler() and it seems prudent
2828-
* to behave similarly as they do. Alternatively all plain backend code
2829-
* waiting on that latch, expecting to get interrupted by query cancels et
2830-
* al., would also need to set set_latch_on_sigusr1.
2828+
* to behave similarly as they do.
28312829
*/
28322830
SetLatch(MyLatch);
28332831

‎src/include/storage/procsignal.h

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -55,6 +55,5 @@ extern int SendProcSignal(pid_t pid, ProcSignalReason reason,
5555
BackendId backendId);
5656

5757
extern void procsignal_sigusr1_handler(SIGNAL_ARGS);
58-
extern PGDLLIMPORT bool set_latch_on_sigusr1;
5958

6059
#endif /* PROCSIGNAL_H */

‎src/test/modules/test_shm_mq/setup.c

Lines changed: 26 additions & 39 deletions
Original file line numberDiff line numberDiff line change
@@ -255,51 +255,38 @@ static void
255255
wait_for_workers_to_become_ready(worker_state *wstate,
256256
volatile test_shm_mq_header *hdr)
257257
{
258-
bool save_set_latch_on_sigusr1;
259258
bool result = false;
260259

261-
save_set_latch_on_sigusr1 = set_latch_on_sigusr1;
262-
set_latch_on_sigusr1 = true;
263-
264-
PG_TRY();
260+
for (;;)
265261
{
266-
for (;;)
262+
int workers_ready;
263+
264+
/* If all the workers are ready, we have succeeded. */
265+
SpinLockAcquire(&hdr->mutex);
266+
workers_ready = hdr->workers_ready;
267+
SpinLockRelease(&hdr->mutex);
268+
if (workers_ready >= wstate->nworkers)
267269
{
268-
int workers_ready;
269-
270-
/* If all the workers are ready, we have succeeded. */
271-
SpinLockAcquire(&hdr->mutex);
272-
workers_ready = hdr->workers_ready;
273-
SpinLockRelease(&hdr->mutex);
274-
if (workers_ready >= wstate->nworkers)
275-
{
276-
result = true;
277-
break;
278-
}
279-
280-
/* If any workers (or the postmaster) have died, we have failed. */
281-
if (!check_worker_status(wstate))
282-
{
283-
result = false;
284-
break;
285-
}
286-
287-
/* Wait to be signalled. */
288-
WaitLatch(MyLatch, WL_LATCH_SET, 0);
289-
290-
/* An interrupt may have occurred while we were waiting. */
291-
CHECK_FOR_INTERRUPTS();
292-
293-
/* Reset the latch so we don't spin. */
294-
ResetLatch(MyLatch);
270+
result = true;
271+
break;
295272
}
273+
274+
/* If any workers (or the postmaster) have died, we have failed. */
275+
if (!check_worker_status(wstate))
276+
{
277+
result = false;
278+
break;
279+
}
280+
281+
/* Wait to be signalled. */
282+
WaitLatch(MyLatch, WL_LATCH_SET, 0);
283+
284+
/* An interrupt may have occurred while we were waiting. */
285+
CHECK_FOR_INTERRUPTS();
286+
287+
/* Reset the latch so we don't spin. */
288+
ResetLatch(MyLatch);
296289
}
297-
PG_CATCH();
298-
{
299-
set_latch_on_sigusr1 = save_set_latch_on_sigusr1;
300-
PG_RE_THROW();
301-
}
302-
PG_END_TRY();
303290

304291
if (!result)
305292
ereport(ERROR,

0 commit comments

Comments
 (0)
pFad - Phonifier reborn

Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.

Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.


Alternative Proxies:

Alternative Proxy

pFad Proxy

pFad v3 Proxy

pFad v4 Proxy