From 50c67c2019ab9ade8aa8768bfe604cd802fe8591 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Thu, 23 Nov 2023 13:31:36 +0200 Subject: [PATCH] Use ResourceOwner to track WaitEventSets. A WaitEventSet holds file descriptors or event handles (on Windows). If FreeWaitEventSet is not called, those fds or handles are leaked. Use ResourceOwners to track WaitEventSets, to clean those up automatically on error. This was a live bug in async Append nodes, if a FDW's ForeignAsyncRequest function failed. (In back branches, I will apply a more localized fix for that based on PG_TRY-PG_FINALLY.) The added test doesn't check for leaking resources, so it passed even before this commit. But at least it covers the code path. In the passing, fix misleading comment on what the 'nevents' argument to WaitEventSetWait means. Report by Alexander Lakhin, analysis and suggestion for the fix by Tom Lane. Fixes bug #17828. Reviewed-by: Alexander Lakhin, Thomas Munro Discussion: https://www.postgresql.org/message-id/472235.1678387869@sss.pgh.pa.us --- .../postgres_fdw/expected/postgres_fdw.out | 7 ++ contrib/postgres_fdw/sql/postgres_fdw.sql | 6 ++ src/backend/executor/nodeAppend.c | 5 +- src/backend/libpq/pqcomm.c | 2 +- src/backend/postmaster/postmaster.c | 2 +- src/backend/postmaster/syslogger.c | 2 +- src/backend/storage/ipc/latch.c | 68 +++++++++++++++++-- src/include/storage/latch.h | 4 +- src/include/utils/resowner.h | 1 + 9 files changed, 84 insertions(+), 13 deletions(-) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 64bcc66b8d..22cae37a1e 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -10809,6 +10809,13 @@ SELECT * FROM result_tbl ORDER BY a; (2 rows) DELETE FROM result_tbl; +-- Test error handling, if accessing one of the foreign partitions errors out +CREATE FOREIGN TABLE async_p_broken PARTITION OF async_pt FOR VALUES FROM (10000) TO (10001) + SERVER loopback OPTIONS (table_name 'non_existent_table'); +SELECT * FROM async_pt; +ERROR: relation "public.non_existent_table" does not exist +CONTEXT: remote SQL command: SELECT a, b, c FROM public.non_existent_table +DROP FOREIGN TABLE async_p_broken; -- Check case where multiple partitions use the same connection CREATE TABLE base_tbl3 (a int, b int, c text); CREATE FOREIGN TABLE async_p3 PARTITION OF async_pt FOR VALUES FROM (3000) TO (4000) diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index 2d14eeadb5..075da4ff86 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -3607,6 +3607,12 @@ INSERT INTO result_tbl SELECT a, b, 'AAA' || c FROM async_pt WHERE b === 505; SELECT * FROM result_tbl ORDER BY a; DELETE FROM result_tbl; +-- Test error handling, if accessing one of the foreign partitions errors out +CREATE FOREIGN TABLE async_p_broken PARTITION OF async_pt FOR VALUES FROM (10000) TO (10001) + SERVER loopback OPTIONS (table_name 'non_existent_table'); +SELECT * FROM async_pt; +DROP FOREIGN TABLE async_p_broken; + -- Check case where multiple partitions use the same connection CREATE TABLE base_tbl3 (a int, b int, c text); CREATE FOREIGN TABLE async_p3 PARTITION OF async_pt FOR VALUES FROM (3000) TO (4000) diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c index 609df6b9e6..af8e37205f 100644 --- a/src/backend/executor/nodeAppend.c +++ b/src/backend/executor/nodeAppend.c @@ -1025,7 +1025,8 @@ ExecAppendAsyncEventWait(AppendState *node) /* We should never be called when there are no valid async subplans. */ Assert(node->as_nasyncremain > 0); - node->as_eventset = CreateWaitEventSet(CurrentMemoryContext, nevents); + Assert(node->as_eventset == NULL); + node->as_eventset = CreateWaitEventSet(CurrentResourceOwner, nevents); AddWaitEventToSet(node->as_eventset, WL_EXIT_ON_PM_DEATH, PGINVALID_SOCKET, NULL, NULL); @@ -1050,7 +1051,7 @@ ExecAppendAsyncEventWait(AppendState *node) return; } - /* We wait on at most EVENT_BUFFER_SIZE events. */ + /* Return at most EVENT_BUFFER_SIZE events in one call. */ if (nevents > EVENT_BUFFER_SIZE) nevents = EVENT_BUFFER_SIZE; diff --git a/src/backend/libpq/pqcomm.c b/src/backend/libpq/pqcomm.c index 522584e597..2802efc63f 100644 --- a/src/backend/libpq/pqcomm.c +++ b/src/backend/libpq/pqcomm.c @@ -207,7 +207,7 @@ pq_init(void) elog(FATAL, "fcntl(F_SETFD) failed on socket: %m"); #endif - FeBeWaitSet = CreateWaitEventSet(TopMemoryContext, FeBeWaitSetNEvents); + FeBeWaitSet = CreateWaitEventSet(NULL, FeBeWaitSetNEvents); socket_pos = AddWaitEventToSet(FeBeWaitSet, WL_SOCKET_WRITEABLE, MyProcPort->sock, NULL, NULL); latch_pos = AddWaitEventToSet(FeBeWaitSet, WL_LATCH_SET, PGINVALID_SOCKET, diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index 7b6b613c4a..7a5cd06c5c 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -1695,7 +1695,7 @@ ConfigurePostmasterWaitSet(bool accept_connections) FreeWaitEventSet(pm_wait_set); pm_wait_set = NULL; - pm_wait_set = CreateWaitEventSet(CurrentMemoryContext, + pm_wait_set = CreateWaitEventSet(NULL, accept_connections ? (1 + NumListenSockets) : 1); AddWaitEventToSet(pm_wait_set, WL_LATCH_SET, PGINVALID_SOCKET, MyLatch, NULL); diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c index 858a2f6b2b..96dd03d9e0 100644 --- a/src/backend/postmaster/syslogger.c +++ b/src/backend/postmaster/syslogger.c @@ -311,7 +311,7 @@ SysLoggerMain(int argc, char *argv[]) * syslog pipe, which implies that all other backends have exited * (including the postmaster). */ - wes = CreateWaitEventSet(CurrentMemoryContext, 2); + wes = CreateWaitEventSet(NULL, 2); AddWaitEventToSet(wes, WL_LATCH_SET, PGINVALID_SOCKET, MyLatch, NULL); #ifndef WIN32 AddWaitEventToSet(wes, WL_SOCKET_READABLE, syslogPipe[0], NULL, NULL); diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c index 2fd386a4ed..d8a69990b3 100644 --- a/src/backend/storage/ipc/latch.c +++ b/src/backend/storage/ipc/latch.c @@ -62,6 +62,7 @@ #include "storage/pmsignal.h" #include "storage/shmem.h" #include "utils/memutils.h" +#include "utils/resowner.h" /* * Select the fd readiness primitive to use. Normally the "most modern" @@ -101,6 +102,8 @@ /* typedef in latch.h */ struct WaitEventSet { + ResourceOwner owner; + int nevents; /* number of registered events */ int nevents_space; /* maximum number of events in this set */ @@ -195,6 +198,31 @@ static void WaitEventAdjustWin32(WaitEventSet *set, WaitEvent *event); static inline int WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout, WaitEvent *occurred_events, int nevents); +/* ResourceOwner support to hold WaitEventSets */ +static void ResOwnerReleaseWaitEventSet(Datum res); + +static const ResourceOwnerDesc wait_event_set_resowner_desc = +{ + .name = "WaitEventSet", + .release_phase = RESOURCE_RELEASE_AFTER_LOCKS, + .release_priority = RELEASE_PRIO_WAITEVENTSETS, + .ReleaseResource = ResOwnerReleaseWaitEventSet, + .DebugPrint = NULL +}; + +/* Convenience wrappers over ResourceOwnerRemember/Forget */ +static inline void +ResourceOwnerRememberWaitEventSet(ResourceOwner owner, WaitEventSet *set) +{ + ResourceOwnerRemember(owner, PointerGetDatum(set), &wait_event_set_resowner_desc); +} +static inline void +ResourceOwnerForgetWaitEventSet(ResourceOwner owner, WaitEventSet *set) +{ + ResourceOwnerForget(owner, PointerGetDatum(set), &wait_event_set_resowner_desc); +} + + /* * Initialize the process-local latch infrastructure. * @@ -323,7 +351,7 @@ InitializeLatchWaitSet(void) Assert(LatchWaitSet == NULL); /* Set up the WaitEventSet used by WaitLatch(). */ - LatchWaitSet = CreateWaitEventSet(TopMemoryContext, 2); + LatchWaitSet = CreateWaitEventSet(NULL, 2); latch_pos = AddWaitEventToSet(LatchWaitSet, WL_LATCH_SET, PGINVALID_SOCKET, MyLatch, NULL); if (IsUnderPostmaster) @@ -541,7 +569,7 @@ WaitLatchOrSocket(Latch *latch, int wakeEvents, pgsocket sock, int ret = 0; int rc; WaitEvent event; - WaitEventSet *set = CreateWaitEventSet(CurrentMemoryContext, 3); + WaitEventSet *set = CreateWaitEventSet(CurrentResourceOwner, 3); if (wakeEvents & WL_TIMEOUT) Assert(timeout >= 0); @@ -716,9 +744,12 @@ ResetLatch(Latch *latch) * * These events can then be efficiently waited upon together, using * WaitEventSetWait(). + * + * The WaitEventSet is tracked by the given 'resowner'. Use NULL for session + * lifetime. */ WaitEventSet * -CreateWaitEventSet(MemoryContext context, int nevents) +CreateWaitEventSet(ResourceOwner resowner, int nevents) { WaitEventSet *set; char *data; @@ -744,7 +775,10 @@ CreateWaitEventSet(MemoryContext context, int nevents) sz += MAXALIGN(sizeof(HANDLE) * (nevents + 1)); #endif - data = (char *) MemoryContextAllocZero(context, sz); + if (resowner != NULL) + ResourceOwnerEnlarge(resowner); + + data = (char *) MemoryContextAllocZero(TopMemoryContext, sz); set = (WaitEventSet *) data; data += MAXALIGN(sizeof(WaitEventSet)); @@ -770,6 +804,12 @@ CreateWaitEventSet(MemoryContext context, int nevents) set->nevents_space = nevents; set->exit_on_postmaster_death = false; + if (resowner != NULL) + { + ResourceOwnerRememberWaitEventSet(resowner, set); + set->owner = resowner; + } + #if defined(WAIT_USE_EPOLL) if (!AcquireExternalFD()) { @@ -834,6 +874,12 @@ CreateWaitEventSet(MemoryContext context, int nevents) void FreeWaitEventSet(WaitEventSet *set) { + if (set->owner) + { + ResourceOwnerForgetWaitEventSet(set->owner, set); + set->owner = NULL; + } + #if defined(WAIT_USE_EPOLL) close(set->epoll_fd); ReleaseExternalFD(); @@ -841,9 +887,7 @@ FreeWaitEventSet(WaitEventSet *set) close(set->kqueue_fd); ReleaseExternalFD(); #elif defined(WAIT_USE_WIN32) - WaitEvent *cur_event; - - for (cur_event = set->events; + for (WaitEvent *cur_event = set->events; cur_event < (set->events + set->nevents); cur_event++) { @@ -2300,3 +2344,13 @@ drain(void) } #endif + +static void +ResOwnerReleaseWaitEventSet(Datum res) +{ + WaitEventSet *set = (WaitEventSet *) DatumGetPointer(res); + + Assert(set->owner != NULL); + set->owner = NULL; + FreeWaitEventSet(set); +} diff --git a/src/include/storage/latch.h b/src/include/storage/latch.h index 99cc47874a..9efc33add8 100644 --- a/src/include/storage/latch.h +++ b/src/include/storage/latch.h @@ -102,6 +102,8 @@ #include +#include "utils/resowner.h" + /* * Latch structure should be treated as opaque and only accessed through * the public functions. It is defined here to allow embedding Latches as @@ -173,7 +175,7 @@ extern void SetLatch(Latch *latch); extern void ResetLatch(Latch *latch); extern void ShutdownLatchSupport(void); -extern WaitEventSet *CreateWaitEventSet(MemoryContext context, int nevents); +extern WaitEventSet *CreateWaitEventSet(ResourceOwner resowner, int nevents); extern void FreeWaitEventSet(WaitEventSet *set); extern void FreeWaitEventSetAfterFork(WaitEventSet *set); extern int AddWaitEventToSet(WaitEventSet *set, uint32 events, pgsocket fd, diff --git a/src/include/utils/resowner.h b/src/include/utils/resowner.h index 0735480214..ddbf19d8da 100644 --- a/src/include/utils/resowner.h +++ b/src/include/utils/resowner.h @@ -74,6 +74,7 @@ typedef uint32 ResourceReleasePriority; #define RELEASE_PRIO_TUPDESC_REFS 400 #define RELEASE_PRIO_SNAPSHOT_REFS 500 #define RELEASE_PRIO_FILES 600 +#define RELEASE_PRIO_WAITEVENTSETS 700 /* 0 is considered invalid */ #define RELEASE_PRIO_FIRST 1