Re: Query interruption with MySQL 5.7 using KILL QUERY in signal handler does no more work

About:

 > B) For some reason, the program does not want to exit() - (must investigate)

In fact we use prepared statements with a sequence of mysql_stmt_init,
mysql_stmt_prepare, mysql_stmt_execute, mysql_stmt_fetch, ... and
mysql_stmt_close.

After the statement was interrupted, we try to free the MySQL statement hanlde with:

mysql_stmt_close(<interrupted-stmt-handle>);

But this API call hangs... (below the strace output)

This was working fine in older versions...

Seb

strace log:

...

sendto(3, "s\0\0\0\26select COUNT(*) from   t2 a"..., 119, 0, NULL, 0) = 119
recvfrom(3, "\f\0\0\1\0\1\0\0\0\1\0\0\0\0\0\0\36\0\0\2\3def\0\0\0\10COUN"..., 16384, 0, NULL, NULL) = 50
sendto(3, "\n\0\0\0\27\1\0\0\0\1\1\0\0\0", 14, 0, NULL, 0) = 14
recvfrom(3, 0x629000005220, 16384, 0, 0, 0) = ? ERESTARTSYS (To be restarted if SA_RESTART is set)

...

When mysql_stmt_close() is called, hangs in recvfrom():

recvfrom(3,





On 07/03/2016 06:55 PM, Sebastien FLAESCH wrote:
> Hi all,
>
> I use the following technique to cancel a long running query:
>
> In the SIGINT signal handler, I restart a connection and I perform a
>
>     KILL QUERY mysql-process-id-of-running-query
>
> This was working find with MySQL 5.6.
>
> But with 5.7 (5.7.11), we get now a different result:
>
> A) The query is still interrupted, but we no longer get an SQL error -1317.
>
> B) For some reason, the program does not want to exit() - (must investigate)
>
> Any clues?
>
>
> With mysql it's working fine:
>
> mysql> select sleep(10);
> ^C^C -- query aborted
> +-----------+
> | sleep(10) |
> +-----------+
> +-----------+
> 1 row in set (2.79 sec)
>
> mysql> \q
> Bye
>
>
> Thanks!
> Seb
>


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