postgrespro.git / summary / log / commit / refs

commit    5fde047f2b41e71706d4ea9e8eb0a401f64192c1
Author:   Andres Freund <andres@anarazel.de>
Date:     Sat Nov 10 04:43:56 2018 +0000

    Combine two flag tests in GetSnapshotData().
    
    Previously the code checked PROC_IN_LOGICAL_DECODING and
    PROC_IN_VACUUM separately. As the relevant variable is marked as
    volatile, the compiler cannot combine the two tests.  As
    GetSnapshotData() is pretty hot in a number of workloads, it's
    worthwhile to fix that.
    
    It'd also be a good idea to get rid of the volatiles altogether. But
    for one that's a larger patch, and for another, the code after this
    change still seems at least as easy to read as before.
    
    Author: Andres Freund
    Discussion: https://postgr.es/m/20181005172955.wyjb4fzcdzqtaxjq@alap3.anarazel.de


 src/backend/storage/ipc/procarray.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 908f62d37e..c861f3e17f 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -1589,14 +1589,11 @@ GetSnapshotData(Snapshot snapshot)
 			TransactionId xid;
 
 			/*
-			 * Backend is doing logical decoding which manages xmin
-			 * separately, check below.
+			 * Skip over backends doing logical decoding which manages xmin
+			 * separately (check below) and ones running LAZY VACUUM.
 			 */
-			if (pgxact->vacuumFlags & PROC_IN_LOGICAL_DECODING)
-				continue;
-
-			/* Ignore procs running LAZY VACUUM */
-			if (pgxact->vacuumFlags & PROC_IN_VACUUM)
+			if (pgxact->vacuumFlags &
+				(PROC_IN_LOGICAL_DECODING | PROC_IN_VACUUM))
 				continue;
 
 			/* Update globalxmin to be the smallest valid xmin */


[parent: 5fc1670bad9b]