[zeromq-dev] zmq_socket and threads

[Thiago Cangussu]

Hi Nishant,

I had a similar problem (
http://lists.zeromq.org/pipermail/zeromq-dev/2012-July/017665.html), but
from my experience you should not have the file descriptor problem opening
"only" 5 sockets every minute. I successfully implemented a socket pool to
solve the issue, but you should definitely redesign if you can :)

Regards,
Thiago


On Thu, Jan 3, 2013 at 1:39 PM, Nishant Mittal <nmittal at rblt.com> wrote:

> Andy, your arguments make sense and I am now creating/closing sockets
> inside each thread. and at some point, as Pieter suggested, we will look at
> redesigning the app so work load is distributed using zeromq to worker
> threads.
>
> thanks
>
>
> On Thu, Jan 3, 2013 at 7:09 AM, Andy Ballingall TF <
> ballingall at thefoundry.co.uk> wrote:
>
>> Nishant,
>>
>> Though not directly related to your question (which is useful to know), I
>> wondered if your use-case should present problems in any event.
>>
>> Isn't the only issue with file descriptors and tcp sockets that the file
>> descriptor cannot be released until TIME_WAIT has elapsed?
>>
>> TIME_WAIT is 'maximum segment lifetime * 2' (MSL*2), and is usually
>> something between 2 and 10 minutes.
>>
>> 'http://en.wikipedia.org/wiki/Maximum_segment_lifetime
>>
>> In your use case, you're only opening a few sockets a minute, so you
>> shouldn't overwhelm the system with sockets in TIME_WAIT state.
>>
>> As far as I know, the only use-cases where this matters is if your rate
>> of socket creation and destruction is sufficiently high to result in a
>> steadily growing number of TIME_WAIT sockets which hit the kernel limit.
>>
>> If, over any specific period of time of length TIME_WAIT, your rate of
>> socket destruction is guaranteed to be below the kernel limit, then you
>> shouldn't reach that limit at all should you?
>>
>> Andy
>>
>>
>>
>>
>> On 2 January 2013 21:23, Nishant Mittal <nmittal at rblt.com> wrote:
>>
>>> I know that zmq_sockets are not thread safe. however, is it an issue if
>>> I ensure a socket is used ONLY by 1 thread at a time?
>>>
>>> the reason is ...
>>> 1) my application creates 5 threads, does some calcs and then the
>>> threads exit
>>> 2) this is done every minute. so every minute 5 new threads are created.
>>> 3) I think i will run into a file descriptor issue if i create sockets
>>> inside the thread (every time the thread is launched). so planning to
>>> create 5 sockets when my application starts and then use 1 socket from 1
>>> thread.
>>>
>>> is this going to be an issue?
>>>
>>> thanks
>>> Nishant
>>>
>>>
>>> _______________________________________________
>>> zeromq-dev mailing list
>>> zeromq-dev at lists.zeromq.org
>>> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>>>
>>>
>>
>>
>> --
>> Andy Ballingall
>> Senior Software Engineer
>>
>> The Foundry
>> 6th Floor, The Communications Building,
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>>
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>
>
> --
> *Nishant Mittal*
> Director, Product Development
> *Rosenblatt Securities Inc*.
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