Java Performance TuningTop Down Approach

Symptoms Memory CPU I/O

Devices Network

Indicators - Windows

Indicators - Linux Sar, top, dstat,etc.

Jumping Board - JConsole Study the JVM Args Heap Usage should follow a saw tooth pattern

denoting there is no leak There should not be any anonymous threads like

‘Thread 1’ Look for creation of dynamic classes in large numbers CPU Usage

Heap ? Heap is utilized throughout the Object Lifecycle starting from new object

creation, variable references, dereferences by variables going out of scope and finally till Garbage Collection

Object references can be represented in a tree fashion as we do deep references and the cumulative size retained at each level can be determined using offline utilities

There can multiple top level objects in the current program flow context that can retain individual object tree

A parent node should be shallow in size such that it does not retain memory compared to its child nodes

When there is a large difference in retained size between parent and child node, i.e drops, there is a possibility of memory leak

Deep Dive – Heap Analysis Online

VisualVM, JRockit, IBM Health Center Profilers

Offline IBM Heap Analyzer Eclipse MAT

Deep Dive – Memory Leaks

CPU ? Thread dumps provides thread status, monitors,

number of threads waiting for the monitor and call stack of methods

Comparing thread dumps taken at frequent intervals can reveal as to which tasks (call stack) are being performed across thread dumps

Online profiling tools can provide hotspot methods Snapshots can provide thread wise call tree, along

with response time

Deep Dive – Threads & Call Stack Online

VisualVM, JRockit, IBM Health Center Profilers

Offline IBM Thread and Monitor Dump Analyzer

Deep Dive – Threads & Call Stack

I/O ?

Study the read, writes and response time of the Java process and identify the device that is heavily utilized or not responding

Study the network traffic in terms of number of connections, bytes sent / received and transfer rate

Deep Dive – I/O

Based on the heavy reads / writes look for input and output streams without buffering, multiple reads of same resources, unnecessary serialization, etc

Re-use of connection, file transfer in uncompressed form, releasing network resources (such as result set, statement and connection), etc

Performance Case Study - Heap Source -

http://javaeesupportpatterns.blogspot.in/2012/07/5-tips-for-proper-java-heap-size.html

Performance Case Study - CPU Loading of DTM Manager for every

XPath Evaluation

Source http://stackoverflow.com/questions/6340802/java-xpath-apache-jaxp-implementation-performance

Best Practices

Understand your application environment such as firewall, layers (web, app & db), third party data providers if any

Use offline tools and less intrusive tools in production environments

Look for tools provided by the JVM vendor or the Application Server vendor

Use JMeter for recreating production scenario in your environment