[libmicrohttpd] Server Loads

[Derrick Bradbury]

Hi all...

Just wanting to see if anyone has noticed this before.

We're running an application in an envirionment and it seems to handle requests up to about 7500/second...

Soon as we start creeping over that strange things happnen. Requests that are at max allowed to run for 6ms take > 10 seconds, connections timeout, and random server reboots (this one may be a xen thing).

I have a little script that collects the reqeusts and then  does some analysis on it:

AVG:0.0229191
MIN: 0.000010
MAX: 7.403612
CNT:83403
0ms:36307
1ms:10847
2ms:5135
3ms:3357
4ms:2606
5ms:2119
6ms - Warning:1775
Timeout:21257
Err:4352

Our MINIMUM response time at about 12,000 requests/second is 0.00001 seconds... and the maximum is 7.4 seconds. And the high number of TIMEOUTS is concerning, as the app shouldn't allow that.

Basically the app takes a URL and submits it to a 3rd party database to be classified. I have a 6ms timeout so there really shouldn't be anything > 6ms, but I'm getting a lot of timeouts.


Some bits of  code:


        struct MHD_Daemon *daemon;
        daemon = MHD_start_daemon (MHD_USE_SELECT_INTERNALLY
                        | MHD_USE_EPOLL_LINUX_ONLY | MHD_USE_EPOLL_TURBO,
                        options.port,
                        NULL, NULL, &answer_to_connection, NULL,
                        MHD_OPTION_THREAD_POOL_SIZE, (unsigned int) options.threads,
                        MHD_OPTION_CONNECTION_LIMIT, (unsigned int) 12000, MHD_OPTION_END);



THe code where I have a timeout at 6ms:
    try {  
      if (!ready) throw 997;
      iurl = MHD_lookup_connection_value (connection, MHD_GET_ARGUMENT_KIND, options.key);
           
      if (!iurl) throw 997;
      if (options.strip_path && strlen(iurl) > 35) iurl=strip_path(iurl);
      if (strcmp("facebook.com",(char*)iurl) == 0 && options.client) {
        page = "76\n78\n80\n";
      }
      else {
        boost::thread cls(classify_url,iurl,boost::ref(rp),internalid);
        if(!cls.timed_join(boost::posix_time::milliseconds(options.timeout))) {
          cls.interrupt(); 
          timeout_counter++;
          page=(options.client)?"998\n":"{\"c\": [998]}";
        }  
        else
          page = rp.c_str();
      }
    }
    catch(...) {
      bad_counter++;
      page=(options.client)?"997\n":"{\"c\": [997]}";
    }