Hi Alexey,
On 4/22/09 4:30 AM, Alexey Botchkov wrote:
> #At file:///home/hf/work/mysql_common/37774/ based on
> revid:alfranio.correia@stripped
>
> 3224 Alexey Botchkov 2009-04-22
> Bug#37774 main.events_bugs fails sporadically
> get_lock() function can crash the system when used inside the event
> handler.
> the interruptible_wait() function used in the implementation calls
> thd->vio_is_connected() in some circumstances and this method leads to
> crash when the thread doesn't have an real connection (thd->net.vio is
> NULL).
>
> Fixed by checking that thd->net.vio isn't NULL.
>
[..]
> === modified file 'sql/item_func.cc'
> --- a/sql/item_func.cc 2009-04-08 23:46:45 +0000
> +++ b/sql/item_func.cc 2009-04-22 07:24:13 +0000
> @@ -3540,7 +3540,7 @@ static int interruptible_wait(THD *thd,
> if (error == ETIMEDOUT || error == ETIME)
> {
> /* Return error if timed out or connection is broken. */
> - if (!timeout || !thd->vio_is_connected())
> + if (!timeout || (thd->net.vio&& !thd->vio_is_connected()))
> break;
> }
> } while (error&& timeout);
>
Hum, this scenario looks fishy. The thread was sleeping on a condition
variable, timed out and found out that its connection has been closed.
This sounds more like a race condition waiting to happen... a race
between the time of the check and of pointer dereference.
How does vio becomes null? the thread is killed or something else?
Regards,
-- Davi Arnaut
