Re: psql tests hangs

On Fri, May 12, 2023 at 2:40 AM Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
wrote:

> pá 12. 5. 2023 v 8:20 odesílatel Kirk Wolak <wolakk(at)gmail(dot)com> napsal:
>
>> On Fri, May 12, 2023 at 1:46 AM Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
>> wrote:
>>
>>> pá 12. 5. 2023 v 6:50 odesílatel Kirk Wolak <wolakk(at)gmail(dot)com> napsal:
>>>
>>>> On Fri, May 12, 2023 at 12:14 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>>>
>>>>> Kirk Wolak <wolakk(at)gmail(dot)com> writes:
>>>>> > Did you try the print statement that Andrey asked Pavel to try?
>>>>> ...
>>>>
>>>>
>>> The strange thing is hanging. Broken tests depending on locale are
>>> usual. But I didn't remember hanging.
>>>
>>> Regards
>>>
>>> Pavel
>>>
>>
>> So, if you do psql -c "..."
>> with both of those \watch instructions, do either one hang? (I am now
>> guessing "no")
>>
>> I know that perl is using a special library to "remote control psql"
>> (like a pseudo terminal, I guess).
>> [I had to abort some of the perl testing in Windows because that perl
>> library didn't work with my psql in Windows]
>>
>> Next, can you detect which process is hanging? (is it perl, the library,
>> psql, ?).
>>
>
> It hangs in perl
>
> but now I found there is dependency on PSQL_PAGER setting
>
> it started pager in background, I had lot of zombie pspg processes
>
> Unfortunately, when I unset this variable, the test hangs still
>
> here is backtrace
>
> Missing separate debuginfos, use: dnf debuginfo-install
> perl-interpreter-5.36.1-496.fc38.x86_64
> (gdb) bt
> #0 0x00007fbbc1129ade in select () from /lib64/libc.so.6
> #1 0x00007fbbc137363b in Perl_pp_sselect () from /lib64/libperl.so.5.36
> #2 0x00007fbbc1317958 in Perl_runops_standard () from
> /lib64/libperl.so.5.36
> #3 0x00007fbbc128259d in perl_run () from /lib64/libperl.so.5.36
> #4 0x000056392bd9034a in main ()
>
> It is waiting on reading from pipe probably
>
> psql is living too, and it is waiting too
>
> Using host libthread_db library "/lib64/libthread_db.so.1".
> 0x00007f071740bc37 in wait4 () from /lib64/libc.so.6
> Missing separate debuginfos, use: dnf debuginfo-install
> glibc-2.37-4.fc38.x86_64 ncurses-libs-6.4-3.20230114.fc38.x86_64
> readline-8.2-3.fc38.x86_64
> (gdb) bt
> #0 0x00007f071740bc37 in wait4 () from /lib64/libc.so.6
> #1 0x00007f07173a9a10 in _IO_proc_close@@GLIBC_2.2.5 () from
> /lib64/libc.so.6
> #2 0x00007f07173b51e9 in __GI__IO_file_close_it () from /lib64/libc.so.6
> #3 0x00007f07173a79fb in fclose@@GLIBC_2.2.5 () from /lib64/libc.so.6
> #4 0x0000000000406be4 in do_watch (query_buf=query_buf(at)entry=0x5ae540,
> sleep=sleep(at)entry=0(dot)01, iter=0, iter(at)entry=3) at command.c:5348
> #5 0x00000000004087a5 in exec_command_watch (scan_state=scan_state(at)entry=0x5ae490,
> active_branch=active_branch(at)entry=true, query_buf=query_buf(at)entry=0x5ae540,
> previous_buf=previous_buf(at)entry=0x5ae560) at command.c:2875
> #6 0x000000000040d4ba in exec_command (previous_buf=0x5ae560,
> query_buf=0x5ae540, cstack=0x5ae520, scan_state=0x5ae490, cmd=0x5ae9a0
> "watch") at command.c:413
> #7 HandleSlashCmds (scan_state=scan_state(at)entry=0x5ae490,
> cstack=cstack(at)entry=0x5ae520, query_buf=0x5ae540, previous_buf=0x5ae560)
> at command.c:230
>
> I am not sure, it is still doesn't work but probably there are some
> dependencies on my setting
>
> PSQL_PAGER and PSQL_WATCH_PAGER
>
> so this tests fails due my setting
>
> [pavel(at)localhost postgresql.master]$ set |grep PSQL
> PSQL_PAGER='pspg -X'
> PSQL_WATCH_PAGER='pspg -X --stream'
>
> Regards
>
> Pavel
>
>
Ummm... We are testing PSQL \watch and you potentially have a
PSQL_WATCH_PAGER that is kicking in?
By chance does that attempt to read/process/understand the \watch ?
Also, if it is interfering with the stream, that would explain it. The
perl library is trying to "control" psql.
If it ends up talking to you instead... All bets are off, imo. I don't
know enough about PSQL_WATCH_PAGER.

Now I would be curious if you changed the test from
SELECT 1 \watch c=3 0.01

to
SELECT 1 \watch 0.01

because that should work. Then I would test
SELECT \watch 0.01 c=3

If you are trying to parse the watch at all, that could break. Then your
code might be trying to "complain",
and then that is screwing up the planned interaction (Just Guessing).

Kirk...