[PATCH v12a 2/4] Centralize resetting SIGCHLD handler
Heikki Linnakangas <heikki.linnakangas@iki.fi>
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
To:
Date: 2026-01-08T18:22:43Z
Lists: pgsql-hackers
---
src/backend/postmaster/autovacuum.c | 2 --
src/backend/postmaster/bgworker.c | 1 -
src/backend/postmaster/bgwriter.c | 5 -----
src/backend/postmaster/checkpointer.c | 5 -----
src/backend/postmaster/pgarch.c | 3 ---
src/backend/postmaster/startup.c | 5 -----
src/backend/postmaster/syslogger.c | 5 -----
src/backend/postmaster/walsummarizer.c | 5 -----
src/backend/postmaster/walwriter.c | 5 -----
src/backend/replication/logical/slotsync.c | 1 -
src/backend/replication/walreceiver.c | 3 ---
src/backend/replication/walsender.c | 3 ---
src/backend/tcop/postgres.c | 7 -------
src/backend/utils/init/miscinit.c | 14 ++++++++++++++
14 files changed, 14 insertions(+), 50 deletions(-)
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 74574e1eaf9..e8180634db5 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -410,7 +410,6 @@ AutoVacLauncherMain(const void *startup_data, size_t startup_data_len)
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, avl_sigusr2_handler);
pqsignal(SIGFPE, FloatExceptionHandler);
- pqsignal(SIGCHLD, SIG_DFL);
/*
* Create a per-backend PGPROC struct in shared memory. We must do this
@@ -1417,7 +1416,6 @@ AutoVacWorkerMain(const void *startup_data, size_t startup_data_len)
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, SIG_IGN);
pqsignal(SIGFPE, FloatExceptionHandler);
- pqsignal(SIGCHLD, SIG_DFL);
/*
* Create a per-backend PGPROC struct in shared memory. We must do this
diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c
index 0104a86b9ec..8ff6a88a141 100644
--- a/src/backend/postmaster/bgworker.c
+++ b/src/backend/postmaster/bgworker.c
@@ -782,7 +782,6 @@ BackgroundWorkerMain(const void *startup_data, size_t startup_data_len)
pqsignal(SIGPIPE, SIG_IGN);
pqsignal(SIGUSR2, SIG_IGN);
- pqsignal(SIGCHLD, SIG_DFL);
/*
* If an exception is encountered, processing resumes here.
diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c
index 1d8947774a9..efd041832a8 100644
--- a/src/backend/postmaster/bgwriter.c
+++ b/src/backend/postmaster/bgwriter.c
@@ -109,11 +109,6 @@ BackgroundWriterMain(const void *startup_data, size_t startup_data_len)
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, SIG_IGN);
- /*
- * Reset some signals that are accepted by postmaster but not here
- */
- pqsignal(SIGCHLD, SIG_DFL);
-
/*
* We just started, assume there has been either a shutdown or
* end-of-recovery snapshot.
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index e4075265495..98c2933a822 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -222,11 +222,6 @@ CheckpointerMain(const void *startup_data, size_t startup_data_len)
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, SignalHandlerForShutdownRequest);
- /*
- * Reset some signals that are accepted by postmaster but not here
- */
- pqsignal(SIGCHLD, SIG_DFL);
-
/*
* Initialize so that first time-driven event happens at the correct time.
*/
diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index fa4bdfe9ab9..36247c8a254 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -238,9 +238,6 @@ PgArchiverMain(const void *startup_data, size_t startup_data_len)
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, pgarch_waken_stop);
- /* Reset some signals that are accepted by postmaster but not here */
- pqsignal(SIGCHLD, SIG_DFL);
-
/* Unblock signals (they were blocked when the postmaster forked us) */
sigprocmask(SIG_SETMASK, &UnBlockSig, NULL);
diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c
index cdbe53dd262..330c10ddb0b 100644
--- a/src/backend/postmaster/startup.c
+++ b/src/backend/postmaster/startup.c
@@ -234,11 +234,6 @@ StartupProcessMain(const void *startup_data, size_t startup_data_len)
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, StartupProcTriggerHandler);
- /*
- * Reset some signals that are accepted by postmaster but not here
- */
- pqsignal(SIGCHLD, SIG_DFL);
-
/*
* Register timeouts needed for standby mode
*/
diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index 9792f638718..74d082ea51c 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -284,11 +284,6 @@ SysLoggerMain(const void *startup_data, size_t startup_data_len)
pqsignal(SIGUSR1, sigUsr1Handler); /* request log rotation */
pqsignal(SIGUSR2, SIG_IGN);
- /*
- * Reset some signals that are accepted by postmaster but not here
- */
- pqsignal(SIGCHLD, SIG_DFL);
-
sigprocmask(SIG_SETMASK, &UnBlockSig, NULL);
#ifdef WIN32
diff --git a/src/backend/postmaster/walsummarizer.c b/src/backend/postmaster/walsummarizer.c
index e1aa102f41d..09a8301d669 100644
--- a/src/backend/postmaster/walsummarizer.c
+++ b/src/backend/postmaster/walsummarizer.c
@@ -264,11 +264,6 @@ WalSummarizerMain(const void *startup_data, size_t startup_data_len)
ALLOCSET_DEFAULT_SIZES);
MemoryContextSwitchTo(context);
- /*
- * Reset some signals that are accepted by postmaster but not here
- */
- pqsignal(SIGCHLD, SIG_DFL);
-
/*
* If an exception is encountered, processing resumes here.
*/
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index 2c3b4f831aa..f2ba5720986 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -109,11 +109,6 @@ WalWriterMain(const void *startup_data, size_t startup_data_len)
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, SIG_IGN); /* not used */
- /*
- * Reset some signals that are accepted by postmaster but not here
- */
- pqsignal(SIGCHLD, SIG_DFL);
-
/*
* Create a memory context that we will do all our work in. We do this so
* that we can reset the context during error recovery and thereby avoid
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..91c17928e9c 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -1541,7 +1541,6 @@ ReplSlotSyncWorkerMain(const void *startup_data, size_t startup_data_len)
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, SIG_IGN);
pqsignal(SIGPIPE, SIG_IGN);
- pqsignal(SIGCHLD, SIG_DFL);
check_and_set_sync_info(MyProcPid);
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index fabe3c73034..06d0fc1c23d 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -258,9 +258,6 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, SIG_IGN);
- /* Reset some signals that are accepted by postmaster but not here */
- pqsignal(SIGCHLD, SIG_DFL);
-
/* Load the libpq-specific functions */
load_file("libpqwalreceiver", false);
if (WalReceiverFunctions == NULL)
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 79fc192b171..f0912f3f670 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -3744,9 +3744,6 @@ WalSndSignals(void)
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, WalSndLastCycleHandler); /* request a last cycle and
* shutdown */
-
- /* Reset some signals that are accepted by postmaster but not here */
- pqsignal(SIGCHLD, SIG_DFL);
}
/* Report shared-memory space needed by WalSndShmemInit */
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index d01a09dd0c4..5d66c80567c 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -4285,13 +4285,6 @@ PostgresMain(const char *dbname, const char *username)
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
pqsignal(SIGUSR2, SIG_IGN);
pqsignal(SIGFPE, FloatExceptionHandler);
-
- /*
- * Reset some signals that are accepted by postmaster but not by
- * backend
- */
- pqsignal(SIGCHLD, SIG_DFL); /* system() requires this on some
- * platforms */
}
/* Early initialization */
diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index ba191977697..8d898790c3e 100644
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -143,6 +143,15 @@ InitPostmasterChild(void)
elog(FATAL, "setsid() failed: %m");
#endif
+ /*
+ * Reset signals that are used by postmaster but not by child processes.
+ *
+ * Currently just SIGCHLD. The handlers for other signals are overridden
+ * later, depending on the child process type.
+ */
+ pqsignal(SIGCHLD, SIG_DFL); /* system() requires this to be SIG_DFL rather
+ * than SIG_IGN on some platforms */
+
/*
* Every postmaster child process is expected to respond promptly to
* SIGQUIT at all times. Therefore we centrally remove SIGQUIT from
@@ -155,6 +164,11 @@ InitPostmasterChild(void)
sigdelset(&BlockSig, SIGQUIT);
sigprocmask(SIG_SETMASK, &BlockSig, NULL);
+ /*
+ * It is up to the *Main() function to set signal handlers appropriate for
+ * the child process and unblock the rest of the signals.
+ */
+
/* Request a signal if the postmaster dies, if possible. */
PostmasterDeathSignalInit();
--
2.53.0.1.gb2826b52eb
--3rzmtywijtp4k7v2
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