Re: [libmicrohttpd] Problem with Keep-Alive and MHD_OPTION_CONNECTION_TIMEOUT in MHD_USE_THREAD_PER_CONNECTION mode

[Christian Grothoff]

Evgeny: I'm not sure I see how this would relates to enabling/disabling
keep-alive. What seemed more likely was that somehow keep-alive doesn't
work for the specific example silvioprog is testing, so the 2nd request
on the same TCP connection always fails (hence the ~50% failure rate).

At least that is my guess.

On 12/07/2015 09:07 AM, Evgeny Grin wrote:
> By default winsock support only 64 connections on single select().
> You can override this be defining FD_SETSIZE to some higher value before
> including winsock headers. MHD detect redefined value and use it when
> needed.
> Just add -DFD_SETSIZE=16000 to command line when building MHD.
> Note that MHD automatically limits number of connections to FD_SETSIZE.
>  
> One problem is discovered: MHD was tried to redefine FD_SETSIZE to 1024
> on W32, but this code was non-functional.
> 
> 
> -- 
> Best Wishes,
> Evgeny Grin
> 
> 
> 
> 07.12.2015, 01:47, "silvioprog" <address@hidden>:
>> Hello bro,
>>
>> Yes, it killed the problem definitively! 3:)
>>
>> I did many tests using different machines and now it works like a
>> charm, thanks a lot for this fix.
>>
>> However ( ^^' ), I saw a small problem, but it is related only to the
>> keep-alive feature, even using previous versions like 0.9.46: when I
>> use keep-alive, I get many errors in many requests. When I disable the
>> keep-alive, I get only some errors. It is very easy to be reproduced,
>> but you need to use some tool like JMeter. Let's go to see that:
>>
>> . get JMeter here [1] and execute its jar file (on Windows, I just
>> double click in the `ApacheJMeter.jar` file);
>> . get this jmx file[2] file and open it in the JMeter (if you prefer,
>> I can explain you what I used in this test);
>> . expand the "Thread Group" hree, select the "Aggregate Report"
>> options, and click the `Start` button after compile and run this[3]
>> example.
>>
>> In my machine, when I kept the line [4] commented (ie, using
>> keep-alive), the result was:
>>
>> Samples: 15000
>> 95% line: 75
>> *Error: 51,52%*
>>
>> But, when I uncommented this line (ie, using connection close instead
>> of keep-alive) and retested it, the result was:
>>
>> Samples: 15000
>> 95% line: 572 // yes, it's OK for `connection: close`
>> *Error: 0,56%*
>>
>> In short: using keep-alive you get ~51,52% errors and connection close
>> only 0,56%. It is a little bit strange, because I did some tests using
>> other servers (NodeJS, Jetty and Nginx) and it works fine, 0,0% erros. :-/
>>
>> [1]
>> http://mirror.nbtelecom.com.br/apache//jmeter/binaries/apache-jmeter-2.13.zip
>> [2] https://www.dropbox.com/s/wiu5gtsflj8omz0/HTTP%20Request.jmx?dl=1
>> [3] http://pastebin.com/3wC5035F
>> [4] MHD_add_response_header(response, MHD_HTTP_HEADER_CONNECTION, "close")
>>
>> On Sat, Dec 5, 2015 at 1:33 PM, Christian Grothoff
>> <address@hidden <mailto:address@hidden>> wrote:
>>
>>     Hi!
>>
>>     Reading the code I noticed an #ifdef WINDOWS'ed call to shutdown()
>>     that
>>     would only be executed (in your particular setting) whenever yet
>>     another
>>     connection was accepted, possibly delaying the TCP connection tear
>>     down.
>>     I've tried to move the respective logic to happen earlier in SVN
>>     36731.
>>      Please try this version, and let me know if this fixes your problem.
>>     (Again, the problem doesn't really hit me on GNU/Linux, so this may or
>>     may not be related.)
>>
>>     Happy hacking!
>>
>>     Christian
>>
>>
>> -- 
>> Silvio Clécio

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