Web module or application server dies or hangs
If an application server dies (its process spontaneously closes), or freezes
(its Web modules stop responding to new requests):
- Isolate the problem by installing Web modules on different servers, if
possible.
- To detect
memory leak problems, enable verbose garbage collection on the application
server. This feature adds detailed statements to the JVM error log file of
the application server about the amount of available and in-use memory. To
set up verbose garbage collection:
- Select Servers > Application Servers > server_name > Process
Definition > Java Virtual Machine, and enable Verbose Garbage Collection.
- Stop and restart the application server.
Periodically, or after the application server stops, browse the log
file for garbage collection statements. Look for statements beginning with
"allocation failure". The string indicates that a need for memory allocation
has triggered a JVM garbage collection (freeing of unused memory). Allocation
failures themselves are normal and not necessarily indicative of a problem.
The allocation failure statement is followed by statements showing how many
bytes are needed and how many are allocated.
If there is a steady increase
in the total amount of free and used memory (the JVM keeps allocating more
memory for itself), or if the JVM becomes unable to allocate as much memory
as it needs (indicated by the bytes needed statement), there might be a memory
leak.
- If
the verbose garbage collection output indicates that the application
server is running out of memory, one of the following problems might be present:
- If an application server spontaneously dies, there
will be an SDUMP. See Using the Error Dump
and Cleanup interface for instructions on how to analyze the dump.
For current information available from IBM Support on known problems and
their resolution, see the IBM Support
page.
IBM Support has documents that can save you time gathering information
needed to resolve this problem. Before opening a PMR, see the IBM Support
page.

Troubleshooting by task: What are you trying to do?
Searchable topic ID:
rtrb_appdies
Last updated: Jun 21, 2007 9:56:50 PM CDT
WebSphere Application Server for z/OS, Version 5.0.2
http://publib.boulder.ibm.com/infocenter/wasinfo/index.jsp?topic=/com.ibm.websphere.zseries.doc/info/zseries/ae/rtrb_appdies.html