[Dnsmasq-discuss] Dnsmasq on high load

[Анатолий Мулярский]

I've looked into the code.
retry_send() is called multiply times from different places.
BUT the static variable retries does not reset before any call in a loop.
There can be a situation where retries is 999 and for the first EAGAIN
we get an error as the retries reaches 1000 as its upper limit.
The solution I can propose is to call retry_send() with a parameter
identifying the place of calling.
In the function retry_send() we must make the check for the parameter
for matching with one from the previous invokation. If it is not true
we must reset retries counter.
The second suggestion is to make the timeout value a configurable option.
And the last - in the error message it would be comfortable to get
more info about the problem request - the client address and its
request as minimal info.
Sorry if I want too much :)
But my problem it does not solve - it only can help identifying the
problem source.


2015-03-11 9:56 GMT+02:00, Анатолий Мулярский <tm1tvk at gmail.com>:
> Thank you for the advice, I'll try it later.
>
> 2015-03-10 19:31 GMT+02:00, Simon Kelley <simon at thekelleys.org.uk>:
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>> On 10/03/15 15:15, Анатолий Мулярский wrote:
>>> As I know, the error message means EAGAIN error. But what the
>>> reason?
>>
>> There's a recent change to dnsmasq, which limits it to waiting for one
>> second for the EAGAIN error to go away.
>>
>> See retry_send() in src/util.c
>>
>>  /* Linux kernels can return EAGAIN in perpetuity when calling
>>      sendmsg() and the relevant interface has gone. Here we loop
>>      retrying in EAGAIN for 1 second max, to avoid this hanging
>>      dnsmasq. */
>>
>> You might try tweaking the code below that to make it wait longer, or
>> not have a timeout.
>>
>> The reason for the EAGAIN is likely that the send queue on the socket
>> if full.
>>
>>
>> Cheers,
>>
>> Simon.
>>
>
>
> --
> Best regards
> Anatoly Muliarski
>


-- 
Best regards
Anatoly Muliarski