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From: Bharath Rupireddy <[email protected]>
To: PostgreSQL Hackers <[email protected]>
Subject: Lockless exit path for ReplicationOriginExitCleanup
Date: Wed, 22 Nov 2023 14:12:06 +0530
Message-ID: <CALj2ACX+YaeRU5xJqR4C7kLsTO_F7DBRNF8WgeHvJZcKtNuK_A@mail.gmail.com> (raw)

Hi,

While looking at the use of session_replication_state, I noticed that
ReplicationOriginLock is acquired in ReplicationOriginExitCleanup()
even if session_replication_state is reset to NULL by
replorigin_session_reset(). Why can't there be a lockless exit path
something like [1] similar to
replorigin_session_reset() which checks session_replication_state ==
NULL without a lock?

[1]
diff --git a/src/backend/replication/logical/origin.c
b/src/backend/replication/logical/origin.c
index 460e3dcc38..99bbe90f6c 100644
--- a/src/backend/replication/logical/origin.c
+++ b/src/backend/replication/logical/origin.c
@@ -1056,6 +1056,9 @@ ReplicationOriginExitCleanup(int code, Datum arg)
 {
        ConditionVariable *cv = NULL;

+       if (session_replication_state == NULL)
+               return;
+
        LWLockAcquire(ReplicationOriginLock, LW_EXCLUSIVE);

        if (session_replication_state != NULL &&

-- 
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

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