Re: pgbench error: (setshell) of script 0; execution of meta-command failed

Andy Fan <zhihuifan1213@163.com> writes:

> Hi:
>
> I run into the {subject} issue with the below setup.
>
> cat foo.sql
>
> \setshell txn_mode echo ${TXN_MODE}
> \setshell speed echo ${SPEED}
> \setshell sleep_ms echo ${SLEEP_MS}
> \setshell subtxn_mode echo ${SUBTXN_MODE}
>
> select 1;
>
> $ TXN_MODE=-1 SPEED=1 SLEEP_MS=0 SUBTXN_MODE=-1 pgbench -n -ffoo.sql postgres -T5 -c4 --exit-on-abort
>
> I *randomly*(7/8) get errors like:
>
> pgbench (18devel)
> pgbench: error: client 2 aborted in command 0 (setshell) of script 0; execution of meta-command failed
> pgbench: error: Run was aborted due to an error in thread 0

I think I have figured out the issue, if you want reproduce it quicker,
you can change the '-T5' to '-T1' in the pgbench command and run many times.

Here is the patch to fix it, would someone take a look at? 

    pgbench: Avoid misleading error for \[set]shell when timer_exceeded.
    
    fgets in executeMetaCommand may return NULL if it receives a signal
    during the shell command is executing. Before this commit, pgbench
    client raises ERROR like below.
    
    pgbench: error: client 3 aborted in command 3 (setshell) of script 0;
    execution of meta-command failed
    
    This behavior is misleading since people may think something is
    wrong. In this commit, we just ignore fgets return NULL when
    timer_exceeded.


-- 
Best Regards
Andy Fan