Performance Questions Part 1

  1. Briefly explain the steps you will follow if you face an out of memory exception ?


Ans :

The first step is to set the context right  Try to gather information of the below stuff

What type of system is experiencing this problem, e.g. development, test, or production

What versions of Process Commander, the application server, operating system, database, and JVM are in use?

What is the current usage of this system?

When did this problem begin and/or when was it first noticed?

What if anything changed in the environment on or around the time the problem first started

Has anything been done to remedy the problem thus far


Gather supportive debug data :

Verbose GC :

JVM Setting

Pega RULES and ALERT Log file

Identify the root cause :

2.What is PerGen ?

Ans : The permanent generation is used by the Sun JVM to store objects that are long lived, and to house certain internal JVM cache structures,

3 . What is message related to permgen error ?

Ans : A permanent generation exhaustion has a special OutOfMemory exception message:

java.lang.OutOfMemoryError: PermGen spac

4. How to resolve permgen issue ?

Ans : Increase the space and check whether it is at per with recommended value or not

5. What is Maximum Classloaders Exceeded Exceptions (IBM JVMs) ?

Ans : When you face an error like this  ERROR: The failure was caused because the class loader limit(-Xmxcl) was exceeded. Please set –Xmxcl to value or greater.

It happens due to the built-in limit on the number of classloaders that it permits in a JVM.


6. How to address Native OOM exceptions ?

Ans : Native OutOfMemory exceptions occur when the JVM process has exhausted the memory areas dedicated to native operations. So verify the memory allocation and act accordingly.

7. How to prevent this Native OOM exception ?

Ans : Generally, the more memory allocated to the main JVM heap , the less that is available for native operations. So allocate memory carefully.

8. What are standard OOM exception ?

Ans :  The standard OutOfMemory exceptionare:

Memory usage spike : A memory spike involves a requester (user or agent) requesting a large amount of memory space for objects

Memory leak

Load exceeds capacity of system

9. What is Memory usage spike ?

Ans :  A memory spike involves a requester (user or agent) requesting a large amount of memory space for objects

10. What are the alert associated with OOM ?

Ans : PEGA 0004, PEGA0027, PEGA0029,PEGA0035

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