Re: Transaction timeout

Testing it again, a couple of questions

1) The current test set has only 2 simple cases – I'd suggest adding one more (that one that didn't work in v1):

gitpod=# set transaction_timeout to '20ms';
SET
gitpod=# begin; select pg_sleep(.01); select pg_sleep(.01); select pg_sleep(.01); commit;
BEGIN
 pg_sleep
----------
 
(1 row)

ERROR:  canceling statement due to transaction timeout

SET
gitpod=# begin; select pg_sleep(.01); select pg_sleep(.01); select pg_sleep(.01); commit;
BEGIN
 pg_sleep
----------
 
(1 row)

 pg_sleep
----------
 
(1 row)

 pg_sleep
----------
 
(1 row)

COMMIT

2) Testing for a longer transaction (2 min), in a gitpod VM (everything is local, no network involved)

// not sure what's happening here, maybe some overheads that are not related to the implementation,

// but the goal was to see how precise the limiting is for longer transactions

gitpod=# set transaction_timeout to '2min';
SET
gitpod=# begin;
BEGIN
gitpod=*# select now(), clock_timestamp(), pg_sleep(3) \watch 1
                Fri 13 Jan 2023 03:49:24 PM UTC (every 1s)

              now              |        clock_timestamp        | pg_sleep
-------------------------------+-------------------------------+----------
 2023-01-13 15:49:22.906924+00 | 2023-01-13 15:49:24.088728+00 |
(1 row)

[...]

                Fri 13 Jan 2023 03:51:18 PM UTC (every 1s)

              now              |        clock_timestamp        | pg_sleep
-------------------------------+-------------------------------+----------
 2023-01-13 15:49:22.906924+00 | 2023-01-13 15:51:18.179579+00 |
(1 row)

ERROR:  canceling statement due to transaction timeout

gitpod=!#
gitpod=!# rollback;
ROLLBACK
gitpod=# select timestamptz '2023-01-13 15:51:18.179579+00' - '2023-01-13 15:49:22.906924+00';
    ?column?    
-----------------
 00:01:55.272655
(1 row)

gitpod=# select interval '2min' - '00:01:55.272655';
    ?column?    
-----------------
 00:00:04.727345
(1 row)

gitpod=# select interval '2min' - '00:01:55.272655' - '4s';
    ?column?    
-----------------
 00:00:00.727345
(1 row)

– it seems we could (should) have one more successful "1s wait, 3s sleep" iteration here, ~727ms somehow wasted in a loop, quite a lot.