While with Oracle for several years there had been many instances when the database performance had not been optimal. This had nothing to with the configuration of the sever but more with tuning of database. Here are some tips which I had been using

Make sure that database statistics is upto-date. As this is one of the factor which can influence explain plan. We can gather statistics by executing following command:

EXEC DBMS_STATS.gather_schema_stats(‘TDWDBA’);

Where TDWDBA is the schema name.

Shahid Qureshi posted “Inspecting Hotspot JVM Options,” which details how to see some of the JVM tuning flags, along with some examinations of what some of the flags mean.

He says there are 717 options for the JVM, a far larger count than the JVM tooldocs page talks about (I got 701, not 717, but big deal, he might be on a different OS than I am so there may be differences – and this is one of the points he makes, that you have to look at the platform your on because the options might change without warning.) They’re primarily for the Oracle/Sun JVM (thus, “Hotspot”) but it’s fascinating to see how deep the tunings go.

You get to see types (uintx, intx, bool, etc), option name, and value when you check out the options – some of them are very fine-grained, which provides a lot of potential when tuning the JVM. It also can show you what some of the options you use regularly actually change; he does a good job of explaining some of the differences that get put in place when using the server VM vs. the client JVM.

Those of you who have not heard about VisualVm , we had talked about it in earlier post Performance tuning your java and J2ee applications.
This is one of the best free tools for monitoring the performance of your java/j2ee application. If you try to use VisualVM with myeclipse, you will have to upgrade from basic license of $30 ! But if you follow the rest of the post , I will explain how to do it for free.

Not many people have worked with it but it sure gives you a deeper insight of your application and helps in locating the problematic areas. The motivation for us was to identify the out of memory exceptions were facing in our application and pinpoint the cause.

In this post we will talk about Visual VM, setting it up with your eclipse and how to monitor your application. We will set up a web application and run visualVM to monitor the application

1. What is Visual VM

Java Management Extensions (JMX) had been part of java since JDK 5.0. JMX enables you to get all the information from the JVM.  VisualVM is a visual tool that integrates some of the commandline JDK tools and gives you powerful profiling capabilities.  VisualVM uses JMX and gives you detailed info about JVM memory, CPU usage, Garbage Collection . It can also profile your objects for CPU and memory usage suggested for local JVM’s only.

More about VisualVM

2.  Installing Visual VM

Visual VM comes bundled with your JDK install ,(post JDK 1.6 update 7). Alternatively you can go to https://visualvm.dev.java.net/download.html and download the file.

Once installed , go to <installed directory>/bin and click visualvm.exe.

It will fire up the visualVM for you. Read more…

Visual VM in JDK 1.6 is one of the best tools for monitoring the performance of your java/j2ee application. I am not sure why Sun has not marketed it well and kep it secret but this is a very good options for developers who always wanted to see how their applications behaves and if there are bottlenecks.

Imagine a developer did some change in application (added a new feature) and would like to know how his changes impact the application. Visual VM is very helpful in these situation. You can use it with standalone java application and can also integrate with your server.

Some of the helpful links on Visual VM are

Visual VM – All in one trouble shooting tool

JDK best kept secret – Visual VM

loitering objects make web company lose money