Hello Alexander and Xuneng,
06.04.2026 22:49, Alexander Korotkov wrote:
Thank you, I've pushed your version of patchset. I made two minor
corrections for patch #2: mention default mode value in the header
comment, and fallback to polling on has_wal_read_bug sparc64+ext4 bug.
I discovered a new test failure, that is apparently caused by new
wait_for_catchup() implementation [1]:
[06:20:23.110](1.069s) not ok 8 - check that the slot state changes to
"extended"
[06:20:23.110](0.001s) # Failed test 'check that the slot state changes to
"extended"'
# at
/Users/ec2-user/bf/goldfish/HEAD/pgsql/src/test/recovery/t/019_replslot_limit.pl
line 140.
[06:20:23.111](0.000s) # got: 'unreserved'
# expected: 'extended'
[06:20:23.231](0.120s) not ok 9 - check that the slot state changes to
"unreserved"
[06:20:23.231](0.000s) # Failed test 'check that the slot state changes to
"unreserved"'
# at
/Users/ec2-user/bf/goldfish/HEAD/pgsql/src/test/recovery/t/019_replslot_limit.pl
line 152.
[06:20:23.231](0.000s) # got: 'lost|'
# expected: 'unreserved|t'
I've managed to reproduce such failures with:
diff --git a/src/backend/replication/walreceiver.c
b/src/backend/replication/walreceiver.c
index 07eac07b9ce..493ce92674e 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -1143,2 +1143,3 @@ XLogWalRcvSendReply(bool force, bool requestReply, bool
checkApply)
+pg_usleep(10000);
/* Get current timestamp. */
diff --git a/src/backend/replication/walsender.c
b/src/backend/replication/walsender.c
index 04aa770d981..19cda3a6b51 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -2521,2 +2521,3 @@ ProcessStandbyReplyMessage(void)
+pg_usleep(100000);
/* the caller already consumed the msgtype byte */
Concretely, a loop:
for i in {1..100}; do echo "ITERATION $i"; PROVE_TESTS="t/019*" make -s check
-C src/test/recovery/ || break; done
failed for me on iterations 2, 1, 7:
ITERATION 7
# +++ tap check in src/test/recovery +++
t/019_replslot_limit.pl .. 8/?
# Failed test 'check that the slot state changes to "extended"'
# at t/019_replslot_limit.pl line 140.
# got: 'unreserved'
# expected: 'extended'
t/019_replslot_limit.pl .. 26/? # Looks like you failed 1 test of 26.
t/019_replslot_limit.pl .. Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/26 subtests
With "WAIT FOR LSN" in wait_for_catchup() disabled, 100 iterations
passed.
Having extra logging added, I could see the key difference.
Failed run:
2026-05-19 22:01:37.968 EEST client backend[3632148] 019_replslot_limit.pl LOG: !!!GetWALAvailability| targetLSN:
0/016C0000, targetSeg: 22, oldestSlotSeg: 23, oldestSegMaxWalSize: 24, oldestSeg: 22
2026-05-19 22:01:37.968 EEST client backend[3632148] 019_replslot_limit.pl STATEMENT: SELECT wal_status FROM
pg_replication_slots WHERE slot_name = 'rep1'
vs
Successful run:
2026-05-19 22:04:18.102 EEST client backend[3633761] 019_replslot_limit.pl LOG: !!!GetWALAvailability| targetLSN:
0/01700000, targetSeg: 23, oldestSlotSeg: 23, oldestSegMaxWalSize: 24, oldestSeg: 23
2026-05-19 22:04:18.102 EEST client backend[3633761] 019_replslot_limit.pl STATEMENT: SELECT wal_status FROM
pg_replication_slots WHERE slot_name = 'rep1'
That is, with WAIT FOR LSN, primary in this test may advance
slot->data.restart_lsn to the expected position after wait_for_catchup()
returns.
[1]
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=goldfish&dt=2026-05-13%2006%3A15%3A03
Best regards,
Alexander
