v2-0001-Fix-burst-checkpoint_req-growth.patch

commit d5a58d8585692be0d24db9414859088e3e7f7dad
Author: Anton A. Melnikov <a.melnikov@postgrespro.ru>
Date:   Tue Sep 6 12:18:56 2022 +0300

    Remove burst growth of the checkpoint_req on replica.
    
    with correcttions according to comment:
     https://www.postgresql.org/message-id/20220907.163946.2214338139097492905.horikyota.ntt%40gmail.com

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 81d339d57d..3ed1a87943 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -9054,3 +9054,20 @@ SetWalWriterSleeping(bool sleeping)
 	XLogCtl->WalWriterSleeping = sleeping;
 	SpinLockRelease(&XLogCtl->info_lck);
 }
+
+/*
+ * Check if a new checkpoint WAL record has been received since the
+ * last restartpoint. So it is possible to create a new one.
+ */
+bool RestartPointAvailable(void)
+{
+	bool result = false;
+
+	SpinLockAcquire(&XLogCtl->info_lck);
+	if (!XLogRecPtrIsInvalid(XLogCtl->lastCheckPointRecPtr)
+		&& XLogCtl->lastCheckPoint.redo > XLogCtl->RedoRecPtr)
+				result = true;
+	SpinLockRelease(&XLogCtl->info_lck);
+
+	return result;
+}
diff --git a/src/backend/access/transam/xlogrecovery.c b/src/backend/access/transam/xlogrecovery.c
index b41e682664..7236e0f0a4 100644
--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -3199,7 +3199,15 @@ XLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr, int reqLen,
 			{
 				(void) GetRedoRecPtr();
 				if (XLogCheckpointNeeded(readSegNo))
-					RequestCheckpoint(CHECKPOINT_CAUSE_XLOG);
+				{
+					/*
+						* If there is no new checkpoint WAL records since the
+						* last restartpoint the creation of new one
+						* will certainly fail, so skip it.
+						*/
+					if (RestartPointAvailable())
+						RequestCheckpoint(CHECKPOINT_CAUSE_XLOG);
+				}
 			}
 		}
 
diff --git a/src/include/access/xlogrecovery.h b/src/include/access/xlogrecovery.h
index 0aa85d90e8..a248f2251e 100644
--- a/src/include/access/xlogrecovery.h
+++ b/src/include/access/xlogrecovery.h
@@ -82,6 +82,7 @@ extern void XLogRecoveryShmemInit(void);
 
 extern void InitWalRecovery(ControlFileData *ControlFile, bool *wasShutdownPtr, bool *haveBackupLabel, bool *haveTblspcMap);
 extern void PerformWalRecovery(void);
+extern bool RestartPointAvailable(void);
 
 /*
  * FinishWalRecovery() returns this.  It contains information about the point