Re: [Sqlrelay-discussion] One more fault tolerance patch

[David M. <dav...@fi...>]

Yeah, this is definitely an issue.  I wonder if the same issue exists 
with other semaphores, depending on exactly where sqlr-connection exits.

I think it would be ok just to reset the semaphore to 0 though, no need 
to check its value first.

On 06/29/2011 10:17 AM, Renat Sabitov wrote:
> Hi David,
>
> I am continue testing and generating ideas :)
>
> If sqlr-connection is killed between signalListenerToRead() and 
> waitForListenerToFinishReading(), sem(3) starts growing above one. 
> This consequently breaks listener-connection communication and leads 
> to hanging listener processes under high load.
>
> The patch changes wait points for sem(3) and sem(2) so the values of 
> this semaphores is set to 0 after wait() completed. Since we can not 
> use "WithUndo" on inter-process communication semaphores, I suppose it 
> is a good idea in general to check the state and revert it to normal.
>
>
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