Application Performance Monitoring

Monitoring of software application usually includes the following and more -
1. Infrastructure instance monitoring like CPU, Memory, Disk I/O, Network, file descriptors, etc
2. Container (Server) monitoring like JVM utilization, server/access/error logs, etc
3. Application monitoring like No of transactions, type of transactions, response times, etc

There are various tools available for monitoring Application. In this article am sharing some practical benefits of using an APM tool (Appdynamics) which I have been experiencing -


1. Ease of installation, administration and usage

2. Provides information on time taken by the application server and time taken by the database server

3. Provides an ability to further drill to exact method, line number and query that causes slowness

4. Ability to quickly find issues related to lock wait time outs, java exceptions, database exceptions, etc

5. Ease of doing before and after optimization analysis to understand impact on response times of business transactions

6. Provides call stack trace, exceptions, slow queries, query count/repetitive queries, API call count, slow async calls, external calls at one place in easy to understand manner which helps the production management personnel to connect with developers

7. Very less overhead on the application servers on which the java and machine agents are deployed

8. Ability to correlate heap usage with the transactions that impacts it

9. Ease in configuration of thresholds, alerts, package includes and excludes, etc.

10. Helps to find root cause of transaction slowness or run time exceptions in code which can be either in a developers code or the code referred/developed by other teams. Appdynamics helps the team to focus on the issue in hand than finger pointing.

11. Ease of finding the issue saves time and effort that otherwise is spent doing focused performance testing. (Last but not the least, its important to mention that excessive dependency on Appdynamics is not good. A Developer/performance tester some times forgets his very job and depends solely on a APM like Appdynamics) 

Java Issues : java.lang.OutOfMemoryError: GC overhead limit exceeded

In many Cases , we see Out Of Memory Issues When Working with Java Applications on the Java Servers.

“GC overhead limit exceeded” is generally thrown by the Garbage Collectors that we use for the JVM. This is generally thrown by serial or parallel collectors.

The issue comes when more amount of time is spent in doing the Garabage Collection and very less than 2% of the heap is recovered.

This may be due to applications that are running very long time or may be due to threads that are struck. Due to these sort of threads ,the objects that are loaded are not reclaimed and are hold-ed by these struck threads for a long time

The serial or parallel collectors throw this exception and this feature is designed to prevent applications from running for an extended period of time while making little or no progress because the heap is too small. If there is unintended object retention , we need to check code for changes If the retention looks normal, and it is a load issue, the heap size would need to be increased.