From 3847ab73a79f11038459b68edfced6a9acf5ecb6 Mon Sep 17 00:00:00 2001
From: Konstantin Knizhnik <konstantin.knizhnik@databricks.com>
Date: Thu, 24 Jul 2025 17:12:25 +0300
Subject: [PATCH] Cleanup perf_counters on backend exit

---
 pgxn/neon/communicator.c       | 11 ++++++++---
 pgxn/neon/neon_perf_counters.c |  7 +++++++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/pgxn/neon/communicator.c b/pgxn/neon/communicator.c
index 03ab065d59..f76c611c8e 100644
--- a/pgxn/neon/communicator.c
+++ b/pgxn/neon/communicator.c
@@ -2551,12 +2551,17 @@ communicator_read_slru_segment(SlruKind kind, int64 segno, neon_request_lsns *re
 void
 communicator_reconfigure_timeout_if_needed(void)
 {
-	bool	needs_set = (MyPState->ring_receive != MyPState->ring_unused ||
-						 (MIN_BACKEND_PREFETCH_LSN != InvalidXLogRecPtr &&
-						  MIN_BACKEND_PREFETCH_LSN != GetXLogReplayRecPtr(NULL))) &&
+	bool	needs_set = MyPState->ring_receive != MyPState->ring_unused &&
 						!AmPrewarmWorker && /* do not pump prefetch state in prewarm worker */
 						readahead_getpage_pull_timeout_ms > 0;
 
+	if (!needs_set && MIN_BACKEND_PREFETCH_LSN != InvalidXLogRecPtr)
+	{
+		if (last_replay_lsn == InvalidXLogRecPtr)
+			MIN_BACKEND_PREFETCH_LSN = InvalidXLogRecPtr;
+		else
+			needs_set = true; /* Can not reset MIN_BACKEND_PREFETCH_LSN now, have to do it later */
+	}
 	if (needs_set != timeout_set)
 	{
 		/*
diff --git a/pgxn/neon/neon_perf_counters.c b/pgxn/neon/neon_perf_counters.c
index dd576e4e73..2a7af15560 100644
--- a/pgxn/neon/neon_perf_counters.c
+++ b/pgxn/neon/neon_perf_counters.c
@@ -13,6 +13,7 @@
 
 #include "funcapi.h"
 #include "miscadmin.h"
+#include "storage/ipc.h"
 #include "storage/proc.h"
 #include "storage/shmem.h"
 #include "utils/builtins.h"
@@ -42,6 +43,11 @@ NeonPerfCountersShmemRequest(void)
 }
 
 
+static void
+NeonPerfCountersReset(int code, Datum arg)
+{
+	memset(MyNeonCounters, 0, sizeof(*MyNeonCounters));
+}
 
 void
 NeonPerfCountersShmemInit(void)
@@ -58,6 +64,7 @@ NeonPerfCountersShmemInit(void)
 	{
 		/* shared memory is initialized to zeros, so nothing to do here */
 	}
+	on_shmem_exit(NeonPerfCountersReset, 0);
 }
 
 static inline void