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Re: [PATCH] utils: Handle errors in worker threads.
From: |
Christopher Baines |
Subject: |
Re: [PATCH] utils: Handle errors in worker threads. |
Date: |
Wed, 05 Feb 2020 18:14:41 +0000 |
User-agent: |
mu4e 1.2.0; emacs 26.3 |
Ludovic Courtès <address@hidden> writes:
> Hi,
>
> Christopher Baines <address@hidden> skribis:
>
>> Previously, if an error occurred, the worker fiber simply never sends a
>> reply. In the case of HTTP requests to Cuirass, where an exception occurs
>> when
>> performing a database query, the fiber handling the request blocks as it
>> never
>> gets a response. I think that this has the potential to cause the process to
>> hit file descriptor limits, as the connections are never responded to.
>>
>> This is fixed by responding with the details of the exception, and then
>> throwing it within the fiber that made the call.
>>
>> * src/cuirass/utils.scm (make-worker-thread-channel): Catch exceptions when
>> calling proc.
>> (call-with-worker-thread): Handle receiving exceptions from the worker
>> thread.
>
> Good catch!
>
>> + (put-message reply
>> + (catch
>> + #t
>
> Please put #t on the same line as ‘catch’. :-)
Ok, I've made this change and pushed as
bb225189fd56d89ec8be926dda269295ccbfe918.
>> + (lambda ()
>> + (apply proc args))
>> + (lambda (key . args)
>> + (cons* 'worker-thread-error key
>> args))))))
>
> As discussed with others at the Guix Days, it’s probably a good idea to
> distinguish “remote” exceptions from local exceptions like you did (and
> unlike what ‘inferior-eval’ does).
>
> LGTM!
I don't quite follow what you're saying here, so feel free to elaborate,
but it also didn't sound like there was a problem to fix, so I've gone
ahead and pushed.
Thanks for taking a look,
Chris
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