Websphere Application Server administrator Interview Question PART 1

Websphere Application Server administrator Interview Question PART 1

 Where would you enable Verbose Garbage Collection? 

A.  From the Admin Console: 
        Application Server -> ServerName -> Process Definition -> Java Virtural Machine – Select verbose garbage collection radio button. 

What is Garbage Collection? 

A. Garbage collection is a process of automatically freeing objects that are no longer referenced by the program. 

How to find the admin console port? 

A.  Navigate to the DMGR home and run the below command to find the Admin console Port

     grep -R "9060" * --exclude=*.log

From the output try to find as below

properties/portdef.props:WC_adminhost=9060

properties/firststepsport.props:9060

or

Open the portdef.props file  from the directoty $WAS_HOME/profiles/Dmgr/properties

and search for WC_adminhost

How to check WAS Version / Build Level?
A. ./WAS_HOME/bin/versionInfo.sh

What is the Default SOAP port number?        
A. 8879 

What are different ways to capture heap dumps for a Websphere JVM? or When to generate ? How to generate ? how to debug ?

Thread Dumps

If you get unexplained server hangs under WebSphere, you can obtain, from the WebSphere server, a thread dump to help diagnose the problem.

In the case of a server hang, you can force an application to create a thread dump.

On unix/Linux machines find the process id (PID) of the hung JVM and issue kill -3 PID.  Look for an output file in the installation root directory with a name like javacore.date.time.id.txt.

Using wasadmin prompt,

get the handle of the server

wsadmin>set jvm [$AdminControl completeObjectName type=JVM,process=server1,*]

execute

wsadmin>$AdminControl invoke $jvm dumpThreads

If an application server spontaneously dies, look for a file. The JVM creates the file in the product directory structure, with a name like javacore[number].txt.

Download thread analyzer from IBM website to analyze the generated thread dumps. (http://www.alphaworks.ibm.com/tech/jca)

Heap Dumps

A heapdump is a snapshot of JVM memory – it shows the live objects on the heap along with references between objects. It is used to determine memory usage patterns and memory leak suspects.

To enable automated heap dump generation support, perform the following steps in the administrative console: (heap dump will generated upon receiving the out.of.memory exceptios)

1. Click Servers > Application servers in the administrative console navigation tree.

2. Click server_name >Runtime Performance Advisor Configuration.

3. Click the Runtime tab.

4. Select the Enable automatic heap dump collection check box.

5. Click OK.

Generate Heap Dump manually

A. use kill -3 PID on unix/linux machines.

What are FFDC logs

A. FFDC is first failure data capture it is a log which the IBM asks when there is a PMR opened with them .