Re: Add CHECK_FOR_INTERRUPTS in polling loop code path in XactLockTableWait

Hi all,

Thank you for the earlier pushed patch—after testing it, things work
well. Per Fujii’s and Kevin’s ideas and suggestions[1], [2], I’ve
tried to extend it to add a new wait event and a progressive backoff
mechanism for XactLockTableWait in logical replication scenarios.

New wait event

• XACT_DONE (“Waiting for a transaction to commit or abort”):

This shows up when a standby is blocked waiting for the primary’s XID replay.

Progressive backoff

• When XactLockTableWait is called from logical replication (oper ==
XLTW_None), the sleep interval doubles each loop up to one second.

• ConditionalXactLockTableWait still uses a fixed 1 ms sleep, since it
is only invoked by heap and index operations.

With the patch applied, a blocked slot‐creation session on standby now shows:

testdb=# SELECT pid, wait_event_type, wait_event, state, query FROM
pg_stat_activity WHERE pid = 62774;
pid | wait_event_type | wait_event | state |
query

-------+-----------------+------------+--------+------------------------------------------------------------------

62774 | IPC | XactDone | active | SELECT *

| | | | FROM
pg_create_logical_replication_slot('my_slot','pgoutput');

(1 row)

Please let me know if you have any feedback or suggestions.

[1] https://www.postgresql.org/message-id/422ea29f-2051-441c-aa5d-5eea04a81b95%40oss.nttdata.com
[2] https://www.postgresql.org/message-id/CAM45KeF6%2B3GtR7dDTAM-kwpGWpnUmAeg%3Djh0N3cd%3DNGBgvVkkA%40mail.gmail.com