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commit    4c2eda67f55a8a263820d12aaeaa7e1dfe7406ee
Author:   Alexander Korotkov <akorotkov@postgresql.org>
Date:     Fri Mar 15 12:31:25 2024 +0000
First released in: 17.0

    Fix race condition in transaction timeout TAP tests
    
    The interruption handler within the injection point can get stuck in an
    infinite loop while handling transaction timeout. To avoid this situation
    we reset the timeout flag before invoking the injection point.
    
    Author: Alexander Korotkov
    Reviewed-by: Andrey Borodin
    Discussion: https://postgr.es/m/ZfPchPC6oNN71X2J%40paquier.xyz


 src/backend/tcop/postgres.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 7ac623019bc..fd4199a0983 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -3409,8 +3409,10 @@ ProcessInterrupts(void)
 		/*
 		 * If the GUC has been reset to zero, ignore the signal.  This is
 		 * important because the GUC update itself won't disable any pending
-		 * interrupt.
+		 * interrupt.  We need to unset the flag before the injection point,
+		 * otherwise we could loop in interrupts checking.
 		 */
+		IdleInTransactionSessionTimeoutPending = false;
 		if (IdleInTransactionSessionTimeout > 0)
 		{
 			INJECTION_POINT("idle-in-transaction-session-timeout");
@@ -3418,13 +3420,12 @@ ProcessInterrupts(void)
 					(errcode(ERRCODE_IDLE_IN_TRANSACTION_SESSION_TIMEOUT),
 					 errmsg("terminating connection due to idle-in-transaction timeout")));
 		}
-		else
-			IdleInTransactionSessionTimeoutPending = false;
 	}
 
 	if (TransactionTimeoutPending)
 	{
 		/* As above, ignore the signal if the GUC has been reset to zero. */
+		TransactionTimeoutPending = false;
 		if (TransactionTimeout > 0)
 		{
 			INJECTION_POINT("transaction-timeout");
@@ -3432,13 +3433,12 @@ ProcessInterrupts(void)
 					(errcode(ERRCODE_TRANSACTION_TIMEOUT),
 					 errmsg("terminating connection due to transaction timeout")));
 		}
-		else
-			TransactionTimeoutPending = false;
 	}
 
 	if (IdleSessionTimeoutPending)
 	{
 		/* As above, ignore the signal if the GUC has been reset to zero. */
+		IdleSessionTimeoutPending = false;
 		if (IdleSessionTimeout > 0)
 		{
 			INJECTION_POINT("idle-session-timeout");
@@ -3446,8 +3446,6 @@ ProcessInterrupts(void)
 					(errcode(ERRCODE_IDLE_SESSION_TIMEOUT),
 					 errmsg("terminating connection due to idle-session timeout")));
 		}
-		else
-			IdleSessionTimeoutPending = false;
 	}
 
 	/*


[parent: a3f349c61292]