[erlang-patches] fix supervisors restarting temporary children
Wed Aug 24 11:10:10 CEST 2011
On 08/23/2011 08:38 PM, Frédéric Trottier-Hébert wrote:
> On 2011-08-23, at 03:48 AM, Henrik Nord wrote:
>> On 08/03/2011 05:07 PM, Frédéric Trottier-Hébert wrote:
>>> git fetch :ferd/otp.git fix_supervisor_temporary_restart
>>> This patch fixes the issue discussed at
>>> http://erlang.org/pipermail/erlang-questions/2011-August/060419.html, namely
>>> that in one_for_all or rest_for_one strategies, the supervisor is
>>> still trying to restart temporary children. Because we don't track
>>> their MFAs entirely, this causes repetitive crashes.
>>> This patch fixes the behaviour by inserting a clause in
>>> terminate_children/2-3 (private function) that will omit temporary
>>> children when building a list of killed processes, to avoid having
>>> the supervisor trying to restart them again.
>>> Only supervisors in need of restarting children used the list, so
>>> the change should be of no impact for the functions that called
>>> terminate_children/2-3 only to kill all children. This also avoids
>>> useless iterations if the filtering step were to be inserted at any
>>> other point in the code.
>>> A test suite has been added to supervisor_SUITE, containing checks
>>> for both one_for_all and rest_for_one. I've only ran the tests for
>>> the suite itself, but all of them pass without a problem.
>>> The commit/diff itself:
>>> Fred Hébert
>>> erlang-patches mailing list
>> Your patch has been reviewed, and we want you to fix the following
>> for it to be graduated.
>> 1) I think the test needs to be extended a bit. I can't see that it
>> checks what happens to the temporary child - i.e. that it is
>> terminated but not restarted. As far as I can understand it only
>> checks that the supervisor survives...
>> 2) There is a minor typo in the description of the test - it says
>> one_for_rest instead of rest_for_one.
>> 3) The behaviour must be documented - i.e. it must be explicitly
>> stated that temporary children under one_for_all or rest_for_one
>> supervisors will be terminated but not restarted.
>> Thank you.
>> /Henrik Nord Erlang/OTP
> 1) Good catch. The broken behaviour would crash the supervisor -- and
> I tested that this was solved, but not that the child isn't retarted.
> This has been fixed.
> 2) also fixed
> 3) I changed it. I wasn't too sure where to put it, but there was only
> one place where temporary children were discussed so I added it there.
> I've amended the commit:
> The fetch command was: git fetch :ferd/otp.git
> Thanks for your time,
> Fred Hébert
> erlang-patches mailing list
/Henrik Nord Erlang/OTP
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