From 05647a44f32972514a6c1543ae6cb1bf1dae3735 Mon Sep 17 00:00:00 2001
From: dongning12 <dning2017@163.com>
Date: Sat, 18 Mar 2023 11:41:44 +0800
Subject: [PATCH] add sleep time to avoid LWLock starvation for buffer content
 lock

---
 src/gausskernel/ddes/adapter/ss_dms_bufmgr.cpp | 9 +++++++++
 src/gausskernel/storage/buffer/bufmgr.cpp      | 8 ++++++--
 src/include/ddes/dms/ss_dms_bufmgr.h           | 1 +
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/gausskernel/ddes/adapter/ss_dms_bufmgr.cpp b/src/gausskernel/ddes/adapter/ss_dms_bufmgr.cpp
index 792a6b533..14114aad8 100644
--- a/src/gausskernel/ddes/adapter/ss_dms_bufmgr.cpp
+++ b/src/gausskernel/ddes/adapter/ss_dms_bufmgr.cpp
@@ -884,3 +884,12 @@ void SSMarkBufferDirtyForERTO(RedoBufferInfo* bufferinfo)
         }
     }
 }
+
+const int ss_buf_retry_threshold = 5;
+long SSGetBufSleepTime(int retry_times)
+{
+    if (retry_times < ss_buf_retry_threshold) {
+        return 5000L * retry_times;
+    }
+    return 1000L * 1000 * 60;
+}
diff --git a/src/gausskernel/storage/buffer/bufmgr.cpp b/src/gausskernel/storage/buffer/bufmgr.cpp
index 53767c729..ab8a0d0ec 100644
--- a/src/gausskernel/storage/buffer/bufmgr.cpp
+++ b/src/gausskernel/storage/buffer/bufmgr.cpp
@@ -5858,6 +5858,7 @@ void LockBuffer(Buffer buffer, int mode)
 {
     volatile BufferDesc *buf = NULL;
     bool need_update_lockid = false;
+    int dms_retry_times = 0;
 
     Assert(BufferIsValid(buffer));
     if (BufferIsLocal(buffer)) {
@@ -5912,7 +5913,8 @@ retry:
             
             LWLockRelease(buf->content_lock);
 
-            pg_usleep(5000L);
+            dms_retry_times++;
+            pg_usleep(SSGetBufSleepTime(dms_retry_times));
             goto retry;
         }
     }
@@ -5984,6 +5986,7 @@ bool TryLockBuffer(Buffer buffer, int mode, bool must_wait)
 bool ConditionalLockBuffer(Buffer buffer)
 {
     volatile BufferDesc *buf = NULL;
+    int dms_retry_times = 0;
 
     Assert(BufferIsValid(buffer));
     if (BufferIsLocal(buffer)) {
@@ -6015,7 +6018,8 @@ retry:
             }
             LWLockRelease(buf->content_lock);
 
-            pg_usleep(5000L);
+            dms_retry_times++;
+            pg_usleep(SSGetBufSleepTime(dms_retry_times));
             goto retry;
         }
     }
diff --git a/src/include/ddes/dms/ss_dms_bufmgr.h b/src/include/ddes/dms/ss_dms_bufmgr.h
index 3017bbf04..692d83c3a 100644
--- a/src/include/ddes/dms/ss_dms_bufmgr.h
+++ b/src/include/ddes/dms/ss_dms_bufmgr.h
@@ -80,5 +80,6 @@ bool SSSegRead(SMgrRelation reln, ForkNumber forknum, char *buffer);
 bool DmsCheckBufAccessible();
 bool SSHelpFlushBufferIfNeed(BufferDesc* buf_desc);
 void SSMarkBufferDirtyForERTO(RedoBufferInfo* bufferinfo);
+long SSGetBufSleepTime(int retry_times);
 
 #endif