Too many open files error on CentOS with SCOPE=system

Question

I am getting the following error log while running a load test on an application

errnoStr=Too many open files, errno=24, SCOPE=system.

Could anybody explain the meaning of SCOPE=system here?

Answer 1

Since that message is not a Resin error message, it's not clear what the SCOPE=system means.

For the open files, you want to look at the ulimit and also check with Resin's /resin-admin for the file descriptor count. If you're using Resin professional, the health system will keep track of the open file descriptors. (Look at the "meters" tab in /resin-admin for the graph.)

> ulimit -a 
...
open files   (-n) 1024

For a load test, you'll want to have lots of open files because you want to stress lots of network connections, and each network connection uses a file descriptor.

If you start Resin as root, Resin can increase the open files automatically. In the jvm-default.log log, Resin will tell you how many it increased it to.

[13-03-05 12:05:37.047] {main}   JNI: file, async keepalive (max=127744), socket

Otherwise, you can set it manually in your operating system. (CentOS uses /etc/limits.conf.)

For the highest performance, make sure you're using Resin Professional. If you're evaluating, you can get an evaluation license. Also, with Resin Pro and load testing, you should look at the /resin-admin graphs and the /resin-admin profiler to see what your bottlenecks are.