recovery-conflict-fail-extra-logging.patch

diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 28c7019402b..cc25abbb5ce 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -2122,6 +2122,8 @@ InvalidatePossiblyObsoleteSlot(uint32 possible_causes,
 
 				last_signaled_pid = active_pid;
 			}
+			else
+				elog(LOG, "XXX: same process (%d) is still blocking us, not signaling again", active_pid);
 
 			/* Wait until the slot is released. */
 			ConditionVariableSleep(&s->active_cv,
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 40312df2cac..c82761f5da3 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -3473,6 +3473,8 @@ SignalRecoveryConflict(PGPROC *proc, pid_t pid, RecoveryConflictReason reason)
 		(void) SendProcSignal(pid, PROCSIG_RECOVERY_CONFLICT, GetNumberFromPGProc(proc));
 		found = true;
 	}
+	else
+		elog(LOG, "XXX: SignalRecoveryConflict signaling pid %d, because it's gone (proc->pid == %d)", pid, proc->pid);
 
 	LWLockRelease(ProcArrayLock);
 
diff --git a/src/backend/storage/ipc/procsignal.c b/src/backend/storage/ipc/procsignal.c
index d47d180a32f..b561dc64265 100644
--- a/src/backend/storage/ipc/procsignal.c
+++ b/src/backend/storage/ipc/procsignal.c
@@ -289,19 +289,24 @@ SendProcSignal(pid_t pid, ProcSignalReason reason, ProcNumber procNumber)
 
 	if (procNumber != INVALID_PROC_NUMBER)
 	{
+		uint32 slot_pid;
 		Assert(procNumber < NumProcSignalSlots);
 		slot = &ProcSignal->psh_slot[procNumber];
 
 		SpinLockAcquire(&slot->pss_mutex);
-		if (pg_atomic_read_u32(&slot->pss_pid) == pid)
+		slot_pid = pg_atomic_read_u32(&slot->pss_pid);
+		if (slot_pid == pid)
 		{
 			/* Atomically set the proper flag */
 			slot->pss_signalFlags[reason] = true;
 			SpinLockRelease(&slot->pss_mutex);
+			elog(LOG, "XXX: SendProcSignal sending SIGUSR1 to pid %d", pid);
 			/* Send signal */
 			return kill(pid, SIGUSR1);
 		}
 		SpinLockRelease(&slot->pss_mutex);
+		elog(LOG, "XXX: SendProcSignal NOT sending SIGUSR1 to pid %d, because it's gone (slot->pss_pid %u)",
+			 pid, slot_pid);
 	}
 	else
 	{
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index d01a09dd0c4..734ff056dad 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -3182,6 +3182,9 @@ report_recovery_conflict(RecoveryConflictReason reason)
 {
 	bool		fatal;
 
+	elog(LOG, "XXX: report_recovery_conflict called; reason %d; IsAbortedTransactionBlockState() %d; DoingCommandRead %d; QueryCancelHoldoffCount %d",
+		 reason, IsAbortedTransactionBlockState(), DoingCommandRead, QueryCancelHoldoffCount);
+
 	if (reason == RECOVERY_CONFLICT_DATABASE)
 	{
 		/* note: no hint about reconnecting, and different errcode */