[hunchentoot-devel] Race condition in stop

Faré fahree at gmail.com
Sun Mar 17 17:49:22 UTC 2013


Looking back at the code, it looks like the race condition can be avoided simply
by moving the
  (shutdown (acceptor-taskmaster acceptor))
below the
  (when soft ...)

Do you want me to send a patch / merge request for this simple change?

—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org
An atheist doesn't have to be someone who thinks he has a proof that there
can't be a god. He only has to be someone who believes that the evidence on
the God question is at a similar level to the evidence on the werewolf
question.  — John McCarthy


On Mon, Mar 11, 2013 at 6:01 PM, Hans Hübner <hans.huebner at gmail.com> wrote:
> Hunchentoot must run on Windows and with LispWorks, so patches that break in
> either of these environments are unlikely to get pulled.  Other than that,
> I'm open to fixes to this problem.
>
> -Hans
>
>
> On Mon, Mar 11, 2013 at 10:55 PM, Faré <fahree at gmail.com> wrote:
>>
>> When we stop an acceptor, we set the stop flag then shutdown the
>> taskmaster. But the acceptor will only stop accepting after timeout
>> and/or after the next connection; in the latter case, said connection
>> will find itself without a taskmaster to process it, and will be
>> dropped on the floor without being processed, while possibly leaking a
>> file descriptor, meanwhile the user on the other end waits 5 minutes
>> for a TCP timeout. That's not very nice, especially if stop is a
>> normal part of frequent server rollouts.
>>
>> To make things better, we could do one or both of these:
>> 1- have the acceptor call the shutdown on the taskmaster after it
>> catches its last request (or lack thereof).
>> 2- have the acceptor use select or poll, so it can be notified of the
>> stop in a timely fashion.
>>
>> Would you accept a patch that does one or the other? What libraries
>> are or aren't OK to pull into hunchentoot to achieve the second? [I
>> suppose, any library that doesn't require linking a .so wrapper.]
>>
>> —♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics•
>> http://fare.tunes.org
>> The hacker: someone who figured things out and made something cool happen.
>>         — Alan Schmitt
>>
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>
>
>
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