From 055c352abbf764a08496e94054137da9e26dac04 Mon Sep 17 00:00:00 2001
From: Simon Riggs <simon@2ndQuadrant.com>
Date: Fri, 1 Jun 2012 09:24:53 +0100
Subject: [PATCH] After any checkpoint, close all smgr files handles in
 bgwriter

---
 src/backend/postmaster/bgwriter.c     |  9 +++++++++
 src/backend/postmaster/checkpointer.c | 25 +++++++++++++++++++++++++
 src/include/postmaster/bgwriter.h     |  2 ++
 3 files changed, 36 insertions(+)

diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c
index 9ad7178aeb..32c254c842 100644
--- a/src/backend/postmaster/bgwriter.c
+++ b/src/backend/postmaster/bgwriter.c
@@ -276,6 +276,15 @@ BackgroundWriterMain(void)
 		 */
 		pgstat_send_bgwriter();
 
+		if (FirstCallSinceLastCheckpoint())
+		{
+			/*
+			 * After any checkpoint, close all smgr files.	This is so we
+			 * won't hang onto smgr references to deleted files indefinitely.
+			 */
+			smgrcloseall();
+		}
+
 		/*
 		 * Sleep until we are signaled or BgWriterDelay has elapsed.
 		 *
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index aa3df37324..6aeade92e6 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -1346,3 +1346,28 @@ UpdateSharedMemoryConfig(void)
 
 	elog(DEBUG2, "checkpointer updated shared memory configuration values");
 }
+
+/*
+ * FirstCallSinceLastCheckpoint allows a process to take an action once
+ * per checkpoint cycle by asynchronously checking for checkpoint completion.
+ */
+bool
+FirstCallSinceLastCheckpoint(void)
+{
+	/* use volatile pointer to prevent code rearrangement */
+	volatile CheckpointerShmemStruct *cps = CheckpointerShmem;
+	static int 	ckpt_done = 0;
+	int 		new_done;
+	bool 		FirstCall = false;
+
+	SpinLockAcquire(&cps->ckpt_lck);
+	new_done = cps->ckpt_done;
+	SpinLockRelease(&cps->ckpt_lck);
+
+	if (new_done != ckpt_done)
+		FirstCall = true;
+
+	ckpt_done = new_done;
+
+	return FirstCall;
+}
diff --git a/src/include/postmaster/bgwriter.h b/src/include/postmaster/bgwriter.h
index d17dd17487..f46d4ad707 100644
--- a/src/include/postmaster/bgwriter.h
+++ b/src/include/postmaster/bgwriter.h
@@ -38,4 +38,6 @@ extern void AbsorbFsyncRequests(void);
 extern Size CheckpointerShmemSize(void);
 extern void CheckpointerShmemInit(void);
 
+extern bool FirstCallSinceLastCheckpoint(void);
+
 #endif   /* _BGWRITER_H */
-- 
2.40.0