HP Jmeter – GC analysis Tutorial

Ram Lakshmanan

www.linkedin.com/in/ramlakshman/

Agenda

• Overview

• Key Visualizers

• Cool Tools

Overview

• HP Jmeter powerful tool for • Garbage Collection Log file analysis

• Heap Dump analysis

• CPU Profiling

• Presentation focuses on Garbage Collection Log File analysis

• Download Location -https://h20392.www2.hp.com/portal/swdepot/displayProductInfo.do?productNumber=HPJMETER

Agenda

• Overview

• Key Visualizers

• Cool Tools

Launch: <Jmeter-dir>/bin/hpjmeter.bat

Open GC File: Go to “File” menu > “Open File”

How to Open GC Log File?

Having trouble in opening GC File?

• Check out – option #2 in http://tier1app.com/2013/06/14/gc-graph-from-gc-logs/

Old Generation space

Perm Generation space

Total space

Too many occurrences of Full GC is a indication of a problem

(Time spent in GC / Total TimeJVM is running). 67% is veryHigh percentage

Useful metric. Can be comparedwith older version of code base

Summary

Total # of GC Events = Scavenge GC events + Old Full GC events + Other full GC events

Usage during peak time in each generation

Shows Summary of the Heap & it’sstatistics

Shows Heap usage in the eden space, old,survivor, and permanent generations after each garbage collection.

Heap usage after GC

Note: After ‘Full GC’ ran – memory reclaimed significantly

Jmeter gets confused. ‘Old full’ and ‘other full’ are same i.e. ‘full’ GC.

Puzzle – Why Scavenge GC not reclaiming memory?

Memory is getting reclaimed. But not pictured clearly in the graph. Because of 2 reasons:1. Objects are created in an

accelerated manner 2. Old Generation is not getting

reclaimed

Custom Views – Reclaimed Bytes

Old GC is reclaiming morebytes than new GC

More Views available

Observations:1. Repeated occurrences of Full GC. 2. No Memory reclaimed

Clear Indication of Memory Leak

Heap usage after GC – Sick JVM

Tab indicate how many times ‘Stop the world’ ran? When did it Ran? How long it took?

Indicates:1. This GC took 2.75 secs to Complete2. It ran at 4:42pm3. It was a “Full GC”

Indicates:1. This GC took 0.2 secs to Complete2. It ran at 4:39:30pm3. It was a “scavenge GC”

Duration – Stop the World

Agenda

• Overview

• Key Visualizers

• Cool Tools

Comparative Analysis

• Helpful tool to compare between GC log files.

• Use cases:• Old code base GC Log vs New code base GC Log

• One application GC Log vs Another application GC Log

How to compare 2 GC logs?

1. Open both GC Log files2. Click on ‘File’ > ‘Compare’ Menu3. Click on ‘Compare’ button

Comparative Analysis

Old Release code base heap usage

New Release code base heap usage

All comparative visualizers

Zoom-in/Zoom-out

Zoom-in: Interested to look certain data points in detail:- Click & drag

Zoom-out: click on this icon

Helpful ‘Help’ Menu

• Go to any one of the View and click on ‘Help’ Menu drop down. It will take you to the appropriate Help section.

• It has precise information

Thank you!

• Visit http://www.tier1app.com for further details on JVM, Memory, GC