0003-Avoid-leaving-DataChecksumState-worker_pid-to-an-old.patch

From 409926ec65f6b27020ee454903aba5b9fbe242db Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Tue, 23 Jun 2026 23:29:59 +0300
Subject: [PATCH 3/6] Avoid leaving DataChecksumState->worker_pid to an old
 value

It might be left to an old value if the launcher was terminated while
a worker was running. launcher_exit() sends SIGTERM to the worker, but
did not clear 'worker_pid'. Clear it, to be tidy.

Also clear it in ProcessDatabase() before starting a new datachecksums
worker, to be sure we start from clean slate. The codepath where
WaitForBackgroundWorkerStartup() returns BGWH_STOPPED but
worker_result != DATACHECKSUMSWORKER_SUCCESSFUL didn't clear it, while
all other codepaths did clear or set it.
---
 src/backend/postmaster/datachecksum_state.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/backend/postmaster/datachecksum_state.c b/src/backend/postmaster/datachecksum_state.c
index 91fff22d70d..6b44e4ee9ea 100644
--- a/src/backend/postmaster/datachecksum_state.c
+++ b/src/backend/postmaster/datachecksum_state.c
@@ -817,6 +817,7 @@ ProcessDatabase(DataChecksumsWorkerDatabase *db)
 
 	LWLockAcquire(DataChecksumsWorkerLock, LW_EXCLUSIVE);
 	DataChecksumState->success = DATACHECKSUMSWORKER_FAILED;
+	DataChecksumState->worker_pid = InvalidPid;
 	LWLockRelease(DataChecksumsWorkerLock);
 
 	memset(&bgw, 0, sizeof(bgw));
@@ -856,9 +857,6 @@ ProcessDatabase(DataChecksumsWorkerDatabase *db)
 		{
 			LWLockRelease(DataChecksumsWorkerLock);
 			pgstat_report_activity(STATE_IDLE, NULL);
-			LWLockAcquire(DataChecksumsWorkerLock, LW_EXCLUSIVE);
-			DataChecksumState->worker_pid = InvalidPid;
-			LWLockRelease(DataChecksumsWorkerLock);
 			return DataChecksumState->success;
 		}
 		LWLockRelease(DataChecksumsWorkerLock);
@@ -951,6 +949,7 @@ launcher_exit(int code, Datum arg)
 			ereport(LOG,
 					errmsg("data checksums launcher exiting while worker is still running, signalling worker"));
 			kill(DataChecksumState->worker_pid, SIGTERM);
+			DataChecksumState->worker_pid = InvalidPid;
 		}
 		LWLockRelease(DataChecksumsWorkerLock);
 	}
-- 
2.47.3