Re: [EXTERNAL] Re: Add non-blocking version of PQcancel

Andres Freund <andres@anarazel.de> writes:
> On 2024-10-01 15:00:00 +0300, Alexander Lakhin wrote:
>> One month later, treehopper has found a way to break that test: [1].
>> The failure log contains:
>> 2024-09-30 19:35:01.485 UTC [3201033:12] pg_regress/query_cancel WARNING: 
>> could not get result of cancel request due to timeout

> Another failure in CI, that cleared up after a retry:
> +WARNING:  could not get result of cancel request due to timeout

Yeah.  This has been happening off-and-on in the buildfarm ever
since we added that test.  I'm not sure if it's just "the test
is unstable" or if it's telling us there's a problem with the
cancel logic.  Scraping the last 3 months worth of buildfarm
logs finds these instances:

  sysname   |    branch     |      snapshot       |           stage            |                                 l

------------+---------------+---------------------+----------------------------+------------------------------------------------------------------
 adder      | HEAD          | 2024-08-29 10:42:09 | postgres_fdwInstallCheck-C | +WARNING:  could not get result of
cancelrequest due to timeout 
 adder      | REL_17_STABLE | 2024-08-29 12:52:00 | postgres_fdwCheck          | +WARNING:  could not get result of
cancelrequest due to timeout 
 froghopper | HEAD          | 2024-10-25 08:31:55 | ContribCheck-C             | +WARNING:  could not get result of
cancelrequest due to timeout 
 grassquit  | HEAD          | 2024-08-20 19:29:20 | postgres_fdwCheck          | +WARNING:  could not get result of
cancelrequest due to timeout 
 mylodon    | HEAD          | 2024-08-30 06:25:46 | postgres_fdwCheck          | +WARNING:  could not get result of
cancelrequest due to timeout 
 pipit      | HEAD          | 2024-11-13 01:12:28 | ContribCheck-C             | +WARNING:  could not get result of
cancelrequest due to timeout 
 snakefly   | REL_17_STABLE | 2024-08-19 11:30:04 | ContribCheck-C             | +WARNING:  could not get result of
cancelrequest due to timeout 
 treehopper | REL_17_STABLE | 2024-09-30 19:21:14 | ContribCheck-C             | +WARNING:  could not get result of
cancelrequest due to timeout 
(8 rows)

            regards, tom lane