clog-diagnostics.patch

diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index 880f18c1473..126502363f5 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -432,7 +432,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
 	proc->clogGroupMemberLsn = lsn;
 
 	nextidx = pg_atomic_read_u32(&procglobal->clogGroupFirst);
-
+elog(WARNING, "TransactionGroupUpdateXidStatus: %d, %d", proc->pgprocno, nextidx);
 	while (true)
 	{
 		/*
@@ -451,9 +451,10 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
 			ProcGlobal->allProcs[nextidx].clogGroupMemberPage != proc->clogGroupMemberPage)
 		{
 			proc->clogGroupMember = false;
+elog(WARNING, "TransactionGroupUpdateXidStatus: return false (%d)", nextidx);
 			return false;
 		}
-
+elog(WARNING, "TransactionGroupUpdateXidStatus: pg_atomic_write_u32 nextidx: %p, %d", &proc->clogGroupNext, nextidx);
 		pg_atomic_write_u32(&proc->clogGroupNext, nextidx);
 
 		if (pg_atomic_compare_exchange_u32(&procglobal->clogGroupFirst,
@@ -461,7 +462,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
 										   (uint32) proc->pgprocno))
 			break;
 	}
-
+elog(WARNING, "TransactionGroupUpdateXidStatus: after while: %d", nextidx);
 	/*
 	 * If the list was not empty, the leader will update the status of our
 	 * XID. It is impossible to have followers without a leader because the
@@ -489,6 +490,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
 		/* Fix semaphore count for any absorbed wakeups */
 		while (extraWaits-- > 0)
 			PGSemaphoreUnlock(proc->sem);
+elog(WARNING, "TransactionGroupUpdateXidStatus: return true (%d)", nextidx);
 		return true;
 	}
 
@@ -540,8 +542,8 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
 	while (wakeidx != INVALID_PGPROCNO)
 	{
 		PGPROC	   *proc = &ProcGlobal->allProcs[wakeidx];
-
 		wakeidx = pg_atomic_read_u32(&proc->clogGroupNext);
+elog(WARNING, "TransactionGroupUpdateXidStatus: pg_atomic_write_u32 INVALID_PGPROCNO: %p, %d", &proc->clogGroupNext, INVALID_PGPROCNO);
 		pg_atomic_write_u32(&proc->clogGroupNext, INVALID_PGPROCNO);
 
 		/* ensure all previous writes are visible before follower continues. */
@@ -553,6 +555,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
 			PGSemaphoreUnlock(proc->sem);
 	}
 
+elog(WARNING, "TransactionGroupUpdateXidStatus: end");
 	return true;
 }