60 Problem Determination for WebSphere for z/OS
6.1 What is a hang?
A WebSphere Application Server hang is when an address space for the application server
on z/OS is not processing work and appears to be idle. A hang can be noticed when the
server no longer processes requests. The scope of this symptom is restricted to a hang in the
WebSphere for z/OS environment.
6.2 Symptom flow chart: Hang
Figure 6-1 shows the flow chart for this symptom. Each box has a number that refers to the
analysis in more detail.
Figure 6-1 Flow chart for symptom: Hang in the application server
6.3 Diagnosing a hang
Follow the these steps to analyze and solve the hang problem:
1. Determine whether it is an application server hang.
Typically, a user who is not getting a browser response reports a hang. This could be a
hang in the application, the HTTP server, or the WebSphere Application Server.
You can perform either of these checks to determine whether it is a WebSphere for z/OS
hang:
Identified
problem and
solution?
9
Yes
1
Determine if
application
server hang
No
No
2
Check and set
hang detection
variables
3
Analyze output
from hang
dectection
variables
Identified
hang?
4
5
Take corrective
action
10
Take corrective
action
11
Search IBM
support pages
12
Identified
problem and
solution?
Yes
Yes
No
13
Assemble
MustGather
documentation
Analyze dump
8
Capture dump of
hung ASID,
master and other
7
Issue diagnostic
commands
6
14
Contact IBM
support
Chapter 6. Hang 61
Run a simple test by entering a display command for the WebSphere for z/OS server
that you suspect has a hang and wait for a response, for example:
MODIFY <server Name>,DISPLAY
If you do not get a response, it is very likely that the WebSphere for z/OS server is
hung.
Check the latest time stamps in the WebSphere for z/OS server logs against the
current system time. How much time has passed between system time and last
recorded activity?
If you get a response from the server or the last recorded activity is close to the system
time, then the problem might be with the HTTP server or the application itself.
Check whether the request from the browser has arrived at the HTTP server by reviewing
the HTTP server access logs and error logs. For more information, see 19.5, “IBM HTTP
Server logs and trace” on page 232. If the HTTP request has arrived at the server and the
HTTP server is responding to requests, then it might be the application that is hung.
2. Check and set hang detection variables.
WebSphere for z/OS V6 has a thread hang detection option and it is enabled by default. To
adjust the hang detection policy values or to disable them, go to the Administrative
Console and select Servers Application Servers server_name. Under
Infrastructure, select Administration Custom Properties. Then, select New. The
properties are:
Name: com.ibm.websphere.threadmonitor.interval
Name: com.ibm.websphere.threadmonitor.threshold
Name: com.ibm.websphere.threadmonitor.false.alarm.threshold
For full explanation of the thread detection properties, search for the WSVR0605W
message at the WebSphere for z/OS V6 Information Center at:
http://publib.boulder.ibm.com/infocenter/wasinfo/v6r0/index.jsp
If the WebSphere for z/OS server address space is hung, you cannot set or adjust these
properties at this time. You must wait until the hang situation is cleared.
3. Analyze output from hang detection variables.
If you have the hang detection variables set, then you can see WSVR0605W messages in
your servant region job log output (Example 6-1).
Example 6-1 WSVR0605W message example
Trace: 2005/07/20 15:45:45.013 01 t=6C1AC8 c=UNK key=P2 (13007002)
ThreadId: 00000016
FunctionName: com.ibm.ws.runtime.component.ThreadMonitorImpl
SourceId: com.ibm.ws.runtime.component.ThreadMonitorImpl
Category: WARNING
ExtendedMessage: BBOO0221W: WSVR0605W: Thread "HAManager.thread.pool: 0"
(00000030) has been active for 642415 milliseconds and may be hung. There is/are
1 thread(s) in total in the server that may be hung.
Note the thread name and ID. They might help you determine the problem when you are
searching the IBM support pages or reporting the problem to IBM.
4. Have you identified the hang?
Using the hang detection properties and the output from the WSVR0605W message, have
you been able to identify the hung thread? If yes, then take corrective action as described
in step 5. If no, issue some diagnostic commands and prepare for a dump as described in
step 6.

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