Re: RFC: Logging plan of the running query

On 2023-06-15 01:48, James Coleman wrote:
> On Tue, Jun 13, 2023 at 11:53 AM James Coleman <jtc331(at)gmail(dot)com>
> wrote:
>>
>> ...
>> I'm going to re-run tests with my patch version + resetting the flag
>> on SIGINT (and any other error condition) to be certain that the issue
>> you uncovered (where backends get stuck after a SIGINT not responding
>> to the requested plan logging) wasn't masking any other issues.
>>
>> As long as that run is clean also then I believe the patch is safe
>> as-is even without the re-entrancy guard.
>>
>> I'll report back with the results of that testing.
>
> The tests have been running since last night, but have been apparently
> hung now for many hours. I haven't been able to fully look into it,
> but so far I know the hung (100% CPU) backend last logged this:
>
> 2023-06-14 02:00:30.045 UTC client backend[84461]
> pg_regress/updatable_views LOG: query plan running on backend with
> PID 84461 is:
> Query Text: SELECT table_name, column_name, is_updatable
> FROM information_schema.columns
> WHERE table_name LIKE E'r_\\_view%'
> ORDER BY table_name, ordinal_position;
>
> The last output from the regression test harness was:
>
> # parallel group (5 tests): index_including create_view
> index_including_gist create_index create_index_spgist
> ok 66 + create_index 36508 ms
> ok 67 + create_index_spgist 38588 ms
> ok 68 + create_view 1394 ms
> ok 69 + index_including 654 ms
> ok 70 + index_including_gist 1701 ms
> # parallel group (16 tests): errors create_cast drop_if_exists
> create_aggregate roleattributes constraints hash_func typed_table
> infinite_recurse
>
> Attaching gdb to the hung backend shows this:
>
> #0 0x00005601ab1f9529 in ProcLockWakeup
> (lockMethodTable=lockMethodTable(at)entry=0x5601ab6484e0
> <default_lockmethod>, lock=lock(at)entry=0x7f5325c913f0) at proc.c:1655
> #1 0x00005601ab1e99dc in CleanUpLock (lock=lock(at)entry=0x7f5325c913f0,
> proclock=proclock(at)entry=0x7f5325d40d60,
> lockMethodTable=lockMethodTable(at)entry=0x5601ab6484e0
> <default_lockmethod>,
> hashcode=hashcode(at)entry=573498161, wakeupNeeded=<optimized out>)
> at lock.c:1673
> #2 0x00005601ab1e9e21 in LockRefindAndRelease
> (lockMethodTable=lockMethodTable(at)entry=0x5601ab6484e0
> <default_lockmethod>, proc=<optimized out>,
> locktag=locktag(at)entry=0x5601ac3d7998, lockmode=lockmode(at)entry=1,
>
> decrement_strong_lock_count=decrement_strong_lock_count(at)entry=false)
> at lock.c:3150
> #3 0x00005601ab1edb27 in LockReleaseAll
> (lockmethodid=lockmethodid(at)entry=1, allLocks=false) at lock.c:2295
> #4 0x00005601ab1f8599 in ProcReleaseLocks
> (isCommit=isCommit(at)entry=true) at proc.c:781
> #5 0x00005601ab37f1f4 in ResourceOwnerReleaseInternal
> (owner=<optimized out>, phase=phase(at)entry=RESOURCE_RELEASE_LOCKS,
> isCommit=isCommit(at)entry=true, isTopLevel=isTopLevel(at)entry=true) at
> resowner.c:618
> #6 0x00005601ab37f7b7 in ResourceOwnerRelease (owner=<optimized out>,
> phase=phase(at)entry=RESOURCE_RELEASE_LOCKS,
> isCommit=isCommit(at)entry=true, isTopLevel=isTopLevel(at)entry=true) at
> resowner.c:494
> #7 0x00005601aaec1d84 in CommitTransaction () at xact.c:2334
> #8 0x00005601aaec2b22 in CommitTransactionCommand () at xact.c:3067
> #9 0x00005601ab200a66 in finish_xact_command () at postgres.c:2783
> #10 0x00005601ab20338f in exec_simple_query (
> query_string=query_string(at)entry=0x5601ac3b0858 "SELECT table_name,
> column_name, is_updatable\n FROM information_schema.columns\n WHERE
> table_name LIKE E'r_\\\\_view%'\n ORDER BY table_name,
> ordinal_position;") at postgres.c:1300
>
> I am unable to connect to the regression test Postgres instance --
> psql just hangs, so the lock seems to have affected the postmaster
> also.
>
> I'm wondering if this might represent a bug in the current patch.

Thanks for running and analyzing the test!

Could you share me how you are running the test?

I imagined something like below, but currently couldn't reproduce it.
- apply both v26-0001 and v27-0002 and build
- run PostgreSQL with default GUCssaaa
- make installcheck-world
- run 'SELECT pg_log_query_plan(pid) FROM pg_stat_activity \watch 0.1'
during make installcheck-world

--
Regards,

--
Atsushi Torikoshi
NTT DATA CORPORATION