Previously posted to dev and bugs. Posting here also in hopes of capturing a greater audience that might have come across this issue before. We have written a modules for apache that for certain reasons requires one hit per child. On apache 1.3 this worked fine with a minor tweak to SCOREBOARD_MAINTENANCE_INTERVAL setting it to 10000 from 1000000. Note that this behavior can be tested without our module by setting "MaxRequestsPerChild 1" We have been running apache 1.3.41 with: MinSpareServers 500 MaxSpareServers 600 StartServers 550 Using JMeter to send some requests if we request a single page using 3 threads, apache has no problem keeping up and doesn't dip below 485 idle servers. With debug logging on you see it jumping from spawning 8 to 16 to 32 children. We didn't need to increase the MAX_SPAWN_RATE from the default of 32 for apache to keep up just fine. Output from apachectl status 197 requests/sec - 28.6 kB/second - 148 B/request 5 requests currently being processed, 492 idle servers ________________________________________________________________ __________________________.___._________________________________ ________________________________._____________________________.. __.___._.W_WW..WW_______________________________________________ __________..__________________._..______________________________ ________________________________________________________________ ________________________________________________________________ ____________________________________....._..._.___________..__.. ........._________.____......................................... Recently we decided we should update our module for apache 2.2 . However we found the performance of apache 2.2 was falling short compared to apache 1.3. Running apache 2.2.22 with the same number of servers falls down pretty quickly with the same load from JMeter. Within a few seconds it drops down to 0 idle connections. In the error_log you see apache constantly saying it's spawning 32 children but the number of children are really low. Example log entry "spawning 32 children, there are 2 idle, and 9 total children" Occasionally it will start catching up but quickly drop back down. Example log entry "spawning 32 children, there are 169 idle, and 180 total child" apachectl status: 27.8 requests/sec - 7.0 kB/second - 256 B/request 13 requests currently being processed, 0 idle workers CCCWCWRSSS............................CCCCCC.................... ................................................................ apachectl status when it starts catching back up: 161 requests/sec - 11.4 kB/second - 72 B/request 4 requests currently being processed, 477 idle workers ___________C____WR____________________._________________________ ________________________________________________________________ ________.______.._......_...C___________________________________ I have tried upping the MAX_SPAWN_RATE to 512 and starting off the idle_spawn_rate at 128 and never letting it fall below that. It seemed like things got marginally better but not by much. I realize most people would think we are crazy for running one hit per child but it's just something we need to do. This has all been tested on the same hardware also. I tried stracing and running gprof but nothing seemed obvious. My best guess at this point is apache is taking to long to close connections or there is some other sleeps or something that I'm not seeing. Any thoughts on what could be the issue would be most appreciated. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscribe@xxxxxxxxxxxxxxxx For additional commands, e-mail: users-help@xxxxxxxxxxxxxxxx
|