v3-0001-Fix-burst-checkpoint_req-growth.patch

commit 6f3ab7b6b5562aaf68ccfdd6dde17c27c2d2869e
Author: Anton A. Melnikov <a.melnikov@postgrespro.ru>
Date:   Wed Dec 7 10:10:58 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 a31fbbff78..02d86bf370 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -8935,3 +8935,20 @@ 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 97b882564f..a88c716197 100644
--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -3196,7 +3196,15 @@ 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 f3398425d8..dcc2e64ca7 100644
--- a/src/include/access/xlogrecovery.h
+++ b/src/include/access/xlogrecovery.h
@@ -83,6 +83,7 @@ extern void InitWalRecovery(ControlFileData *ControlFile,
 							bool *wasShutdown_ptr, bool *haveBackupLabel_ptr,
 							bool *haveTblspcMap_ptr);
 extern void PerformWalRecovery(void);
+extern bool RestartPointAvailable(void);
 
 /*
  * FinishWalRecovery() returns this.  It contains information about the point