From 51ef64973b747bb563c425ef2b717677ba24dc35 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Tue, 17 Feb 2026 23:04:26 +0200 Subject: [PATCH v10 2/5] Use standard die() handler for SIGTERM in bgworkers The previous default bgworker_die() signal would exit with elog(FATAL) directly from the signal handler. That could cause deadlocks or crashes if the signal handler runs while we're e.g holding a spinlock or in the middle of a memory allocation. All the built-in background workers overrode that to use the normal die() handler and CHECK_FOR_INTERRUPTS(). Let's make that the default for all background workers. Some extensions relying on the old behavior might need to adapt, but the new default is much safer and the right thing to do for most background workers. --- doc/src/sgml/bgworker.sgml | 10 ++++++++++ src/backend/access/transam/parallel.c | 1 - src/backend/postmaster/bgworker.c | 16 +--------------- .../replication/logical/applyparallelworker.c | 1 - src/backend/replication/logical/launcher.c | 1 - src/backend/replication/logical/worker.c | 1 - 6 files changed, 11 insertions(+), 19 deletions(-) diff --git a/doc/src/sgml/bgworker.sgml b/doc/src/sgml/bgworker.sgml index 4699ef6345f..2affba74382 100644 --- a/doc/src/sgml/bgworker.sgml +++ b/doc/src/sgml/bgworker.sgml @@ -232,6 +232,8 @@ typedef struct BackgroundWorker + A well-behaved background worker must react promptly to standard signals + that the postmaster uses to control its child processes. Signals are initially blocked when control reaches the background worker's main function, and must be unblocked by it; this is to allow the process to customize its signal handlers, if necessary. @@ -240,6 +242,14 @@ typedef struct BackgroundWorker BackgroundWorkerBlockSignals. + + The default signal handlers merely set interrupt flags + that are processed later by CHECK_FOR_INTERRUPTS(). + CHECK_FOR_INTERRUPTS() should be called in any + long-running loop to ensure that the background worker doesn't prevent the + system from shutting down in a timely fashion. + + If bgw_restart_time for a background worker is configured as BGW_NEVER_RESTART, or if it exits with an exit diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c index fe00488487d..44786dc131f 100644 --- a/src/backend/access/transam/parallel.c +++ b/src/backend/access/transam/parallel.c @@ -1327,7 +1327,6 @@ ParallelWorkerMain(Datum main_arg) InitializingParallelWorker = true; /* Establish signal handlers. */ - pqsignal(SIGTERM, die); BackgroundWorkerUnblockSignals(); /* Determine and set our parallel worker number. */ diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c index d4031ac3787..133af5aee97 100644 --- a/src/backend/postmaster/bgworker.c +++ b/src/backend/postmaster/bgworker.c @@ -718,20 +718,6 @@ SanityCheckBackgroundWorker(BackgroundWorker *worker, int elevel) return true; } -/* - * Standard SIGTERM handler for background workers - */ -static void -bgworker_die(SIGNAL_ARGS) -{ - sigprocmask(SIG_SETMASK, &BlockSig, NULL); - - ereport(FATAL, - (errcode(ERRCODE_ADMIN_SHUTDOWN), - errmsg("terminating background worker \"%s\" due to administrator command", - MyBgworkerEntry->bgw_type))); -} - /* * Main entry point for background worker processes. */ @@ -787,7 +773,7 @@ BackgroundWorkerMain(const void *startup_data, size_t startup_data_len) pqsignal(SIGUSR1, SIG_IGN); pqsignal(SIGFPE, SIG_IGN); } - pqsignal(SIGTERM, bgworker_die); + pqsignal(SIGTERM, die); /* SIGQUIT handler was already set up by InitPostmasterChild */ pqsignal(SIGHUP, SIG_IGN); diff --git a/src/backend/replication/logical/applyparallelworker.c b/src/backend/replication/logical/applyparallelworker.c index 8a01f16a2ca..1730ace5490 100644 --- a/src/backend/replication/logical/applyparallelworker.c +++ b/src/backend/replication/logical/applyparallelworker.c @@ -879,7 +879,6 @@ ParallelApplyWorkerMain(Datum main_arg) * receiving SIGTERM. */ pqsignal(SIGHUP, SignalHandlerForConfigReload); - pqsignal(SIGTERM, die); pqsignal(SIGUSR2, SignalHandlerForShutdownRequest); BackgroundWorkerUnblockSignals(); diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c index 3ed86480be2..e6112e11ec2 100644 --- a/src/backend/replication/logical/launcher.c +++ b/src/backend/replication/logical/launcher.c @@ -1213,7 +1213,6 @@ ApplyLauncherMain(Datum main_arg) /* Establish signal handlers. */ pqsignal(SIGHUP, SignalHandlerForConfigReload); - pqsignal(SIGTERM, die); BackgroundWorkerUnblockSignals(); /* diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c index 32725c48623..75af3a71ca8 100644 --- a/src/backend/replication/logical/worker.c +++ b/src/backend/replication/logical/worker.c @@ -5890,7 +5890,6 @@ SetupApplyOrSyncWorker(int worker_slot) /* Setup signal handling */ pqsignal(SIGHUP, SignalHandlerForConfigReload); - pqsignal(SIGTERM, die); BackgroundWorkerUnblockSignals(); /* -- 2.47.3