[WebSphere] Configuring the hang detection policy

WebSphere에서 Hang으로 의심할 수 있을 정도로 오래 실행되는 Thread를 Check하는 설정값을 변경하는 방법이다.

The thread hang detection option is enabled by default. To adjust the hang detection policy values, or to disable hang detection completely:

1. From the administrative console, click Servers > Application Servers > server_name
2. Under Server Infrastructure, click Administration > Custom Properties
3. Click New.
4. Add the following properties:

   Name: com.ibm.websphere.threadmonitor.interval
   Value:  The frequency (in seconds) at which managed threads in the selected 
           application server will be interrogated.
   Default: 180 seconds (three minutes). 
   
   Name: com.ibm.websphere.threadmonitor.threshold
   Value:   The length of time (in seconds) in which a thread can be active 
            before it is considered hung.  Any thread that is detected as 
            active for longer than this length of time is reported as hung.
   Default: The default value is 600 seconds (ten minutes).
   
   Name:com.ibm.websphere.threadmonitor.false.alarm.threshold 
   Value: The number of times (T) that false alarms can occur 
          before automatically increasing the threshold. It is possible that a 
          thread that is reported as hung eventually completes its work, 
          resulting in a false alarm.  A large number of these events indicates 
          that the threshhold value is too small. The hang detection facility can 
          automatically respond to this situation: For every T false alarms, the 
          threshold T is increased by a factor of 1.5. Set the value to 
          zero (or less) to disable the automatic adjustment. 
   Default: 100
   
   Name: com.ibm.websphere.threadmonitor.dump.java
   Value: Set to true to cause a javacore to be created when a hung thread
              is detected and a WSVR0605W message is printed.  The threads
              section of the javacore can be analyzed to determine what
              the reported thread and other related threads are doing.
   Default: False

   To disable the hang detection option, set the com.ibm.websphere.threadmonitor.interval property to less than or equal to zero.
5. Click Apply.
6. Click OK.
7. Save the changes. Make sure a file synchronization is performed before restarting the servers.
8. Restart the Application Server for the changes to take effect.