Fix parallel retrieve cursor check timeout never going quiet

src/backend/cdb/endpoint/cdbendpointutils.c

@@ -599,3 +599,16 @@ enable_parallel_retrieve_cursor_check_timeout(void)
 							 GP_PARALLEL_RETRIEVE_CURSOR_CHECK_PERIOD_MS);
 	}
 }
+
+/*
+ * Disable the timeout of parallel retrieve cursor check.
+ *
+ * Safe to call unconditionally; disable_timeout() is a no-op when the
+ * timeout is not active.
+ */
+void
+disable_parallel_retrieve_cursor_check_timeout(void)
+{
+	if (Gp_role == GP_ROLE_DISPATCH)
+		disable_timeout(GP_PARALLEL_RETRIEVE_CURSOR_CHECK_TIMEOUT, false);
+}

src/backend/commands/portalcmds.c

@@ -393,8 +393,8 @@ PortalCleanup(Portal portal)
 		}
 	}
 
-	/* 
-	 * If resource scheduling is enabled, release the resource lock. 
+	/*
+	 * If resource scheduling is enabled, release the resource lock.
 	 */
 	if (IsResQueueLockedForPortal(portal))
 	{
@@ -410,6 +410,18 @@ PortalCleanup(Portal portal)
 	{
 		BackoffBackendEntryExit();
 	}
+
+	/*
+	 * If this was a PARALLEL RETRIEVE CURSOR and no others remain, stop
+	 * the periodic check timer immediately rather than waiting for the
+	 * next stray SIGALRM to find a zero count and quiet itself.
+	 * queryDesc was set to NULL above, so the now-cleaned portal is no
+	 * longer counted by GetNumOfParallelRetrieveCursors().
+	 */
+	if (PortalIsParallelRetrieveCursor(portal) &&
+		Gp_role == GP_ROLE_DISPATCH &&
+		GetNumOfParallelRetrieveCursors() == 0)
+		disable_parallel_retrieve_cursor_check_timeout();
 }
 
 /*

src/backend/utils/init/postinit.c

@@ -1894,20 +1894,22 @@ GpParallelRetrieveCursorCheckTimeoutHandler(void)
 
 		/* It calls cdbdisp_checkForCancel(), which doesn't raise error */
 		gp_check_parallel_retrieve_cursor_error();
-		int num = GetNumOfParallelRetrieveCursors();
-
-		/* Reset the alarm to check after a timeout */
-		if (num > 0)
-		{
-			elog(DEBUG1, "There are still %d parallel retrieve cursors alive", num);
-			enable_parallel_retrieve_cursor_check_timeout();
-		}
 	}
 	else
 	{
 		elog(DEBUG1, "DoingCommandRead is false, check parallel cursor timeout delay");
-		enable_parallel_retrieve_cursor_check_timeout();
 	}
+
+	/*
+	 * Only re-arm the periodic check while parallel retrieve cursors are
+	 * still alive. Re-arming unconditionally (the previous behavior) kept
+	 * a SIGALRM firing every GP_PARALLEL_RETRIEVE_CURSOR_CHECK_PERIOD_MS
+	 * for the rest of the backend's life, which interfered with unrelated
+	 * code paths -- most visibly truncating fault-injection 'sleep'
+	 * windows used by isolation2 tests.
+	 */
+	if (GetNumOfParallelRetrieveCursors() > 0)
+		enable_parallel_retrieve_cursor_check_timeout();
 }
 
 /*

src/include/cdb/cdbendpoint.h

@@ -137,6 +137,7 @@ extern void AtAbort_EndpointExecState(void);
 extern void allocEndpointExecState(void);
 extern bool gp_check_parallel_retrieve_cursor_error(void);
 extern void enable_parallel_retrieve_cursor_check_timeout(void);
+extern void disable_parallel_retrieve_cursor_check_timeout(void);
 
 /*
  * Below functions should run on Endpoints(QE/Entry DB).