Most Asked WebLogic Interview Questions and Answers
What are the causes for server crash?
The major reasons for the occurrence of server crash are the native IO, JVM, supported configuration, JDBC driver issues and SSL native libraries.
How can you solve the issue of server crash?
A crash associated with JVM is capable of generating hs_err_pid file. You need to refer this file for finding out the root cause for such a crash. In the case of native IO being the origin of thread, you need to disable it. If the origin of the problem is from the driver, need to contact the driver team.
How can Server Hang be solved?
Java WebLogic.Admin PING needs to be checked for finding whether you get a normal and positive response. You can find out the root cause for hanging from this file. You just need to rectify the errors that are identified from this file.
Explain the reasons for server hang?
The major reasons that lead to the server hang are memory leak, deadlock, and long time for returning.
Define memory leak ?
Memory leak is the condition that arises when the objects get retained in the heap even after they have no use.
What causes the condition OUT OF MEMORY?
There are various reasons that can lead to this condition and they are
- Insufficient size of the heap compared to the extra load.
- Placing of the objects takes longer period of time like that of HTTP sessions.
- Occurrence of memory leak inside the application code.
- The prevention of occurrence of full GC because of JVM bug.
How can the OUT OF MEMORY be solved?
There is a possibility for collecting the memory data after enabling GC – verbose. If the condition has aroused because of HTTP session, then it will be automatically solved when the session gets time out. You should also verify the code associated with the handling of jdbc connectivity. You should also optimize the size of the heap by considering the load.
When can high usage of CPU occur?
This is the condition that usually occurs when a single thread or process makes use of a larger portion of the CPU in an unexpected manner.
How can the issue associated with high CPU usage be solved?
In windows platform the issue of CPU high usage can easily be solved by making use of pslist and also with the process explorer to observe the function performed by the thread or the process.
Explain the term clustering?
Clustering is the process of grouping the servers together for accomplishing high percentage of scalability and availability.
What is the purpose of clustering?
The major goal of performing the process of clustering is to make high scalability as well as availability of the servers possible. This process also helps in balancing the load in a proper manner and also accomplishes failover.
How can cluster communication occur?
The communication through cluster is made possible by the multicast IP as well as port by the process of sending periodic messages which are normally called as heartbeat messages.
What are the various types of WebLogic installations?
The WebLogic installation usually occurs in three different modes which are:
- Graphical mode
- Console mode
- Silent mode.
What is Graphic mode?
It is a kind of installation type that makes use of interactive GUI.
What is console mode?
This is a kind of installation type that follows interactive text based method.
What is silent mode?
This is a method of installation that is non-interactive and is usually based on the .xml properties – file.