修复备机读组获取快照死锁问题Offering: openGaussDevMore detail: standby read

Match-id-06894f7e495d72c5763653105cbd2c8eee989c81

src/gausskernel/storage/buffer/bufmgr.cpp

@@ -4764,6 +4764,29 @@ int GetThreadBufferLeakNum(void)
     return refCountErrors;
 }
 
+bool CheckForBufferPin(void)
+{
+    PrivateRefCountEntry *res = NULL;
+
+    for (int i = 0; i < REFCOUNT_ARRAY_ENTRIES; i++) {
+        res = &t_thrd.storage_cxt.PrivateRefCountArray[i];
+
+        if (res->buffer != InvalidBuffer) {
+            return true;
+        }
+    }
+
+    if (t_thrd.storage_cxt.PrivateRefCountOverflowed) {
+        HASH_SEQ_STATUS hstat;
+        hash_seq_init(&hstat, t_thrd.storage_cxt.PrivateRefCountHash);
+        while ((res = (PrivateRefCountEntry *)hash_seq_search(&hstat)) != NULL) {
+            hash_seq_term(&hstat);
+            return true;
+        }
+    }
+    return false;
+}
+
 /*
  *		CheckForBufferLeaks - ensure this backend holds no buffer pins
  *

src/gausskernel/storage/ipc/procarray.cpp

@@ -2120,6 +2120,8 @@ RETRY:
     bool retry_get = false;
     uint64 retry_count = 0;
     const static uint64 WAIT_COUNT = 0x7FFFF;
+    bool get_snapshot_by_self = CheckForBufferPin() || forHSFeedBack;
+
     /* reset xmin before acquiring lwlock, in case blocking redo */
     t_thrd.pgxact->xmin = InvalidTransactionId;
 RETRY_GET:
@@ -2184,7 +2186,7 @@ RETRY_GET:
                 goto RETRY_GET;
             }
 #ifndef ENABLE_MULTIPLE_NODES
-        } else if (forHSFeedBack) {
+        } else if (get_snapshot_by_self) {
             LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
             if ((t_thrd.xact_cxt.ShmemVariableCache->standbyXmin
                 <= t_thrd.xact_cxt.ShmemVariableCache->standbyRedoCleanupXmin)

src/include/storage/buf/bufmgr.h

@@ -410,6 +410,7 @@ extern void RangeForgetBuffer(RelFileNode node, ForkNumber forkNum, BlockNumber
 
 extern void DropSegRelNodeSharedBuffer(RelFileNode node, ForkNumber forkNum);
 extern int GetThreadBufferLeakNum(void);
+extern bool CheckForBufferPin(void);
 extern void flush_all_buffers(Relation rel, Oid db_id, HTAB *hashtbl = NULL);
 /* in localbuf.c */
 extern void ForgetLocalBuffer(RelFileNode rnode, ForkNumber forkNum, BlockNumber blockNum);