How to determine the ulimit settings of a running WebSphere Application Server process on Linux

Answer

There are a number of situations where determining the ulimit settings of a running WebSphere Application Server process may be necessary. The more common scenarios include determining the maximum number of file descriptors for a given process or generating a system core from a given process.


Step 1
-Determine the Process ID (PID) of the IBM WebSphere Application Server process to be investigated.

If the PID is already known, proceed to step 2.

If the PID is unknown then inspect the contents of the following file to determine the PID:

<install_root>/profiles/<profile_name>/logs/<server_name>/<server_name>.pid

• This file should exist if the server is currently running. Exceptional circumstances could lead to a situation where this file exists and the server is not running.

Step 2
Once the PID is known, inspect the file at the following location:

Location:     /proc/<PID>

File:         limits

• The contents of this file is similar to the output of the "ulimit -a" command.

Limitations
This method is only available to more recent versions of IBM WebSphere Application Server supported Linux operating systems.

The following is a list of minimum operating system versions and maintenance levels where this technique is usable:

• RHEL 4 Update 7
• RHEL 5 Update 2
• SLES 10 Service Pack 3
• SLES 11

There may be some exceptions to this list, and this list is not necessarily exhaustive; however, all the major maintenance levels (Updates / Service Packs) for RHEL 4 and 5 and SLES 9, 10, and 11 were tested. This list reflects the findings of those tests.

There may be some incremental maintenance that can be applied to support this method prior to the above versions and maintenance levels as only major maintenance levels were tested.