Diving into JVM for profiling

To profile JVM, you need to know Java Heap, JMX and Class loader. This slide introduces them for you.

Need an introduction for GC? Please see another slide.
https://speakerdeck.com/eller86/garbage-collection-of-oracle-jdk6

Transcript

1. Diving into JVM -for profiling- 2012/May/18 Kengo TODA 12೥4݄18೔ਫ༵೔
2. To know bottleneck 12೥4݄18೔ਫ༵೔
3. 3 topics Java Heap JMX (Java Management Extensions) Class loader 12೥4݄18೔ਫ༵೔
4. Java Heap Mainly JVM uses Java Heap to store instances You can use `-Xmx` and `-Xms` to specify the size of Java Heap Mark & Sweep is famous algorithm, but JVM can use another ones 12೥4݄18೔ਫ༵೔
5. How Java object uses Java Heap quoted from dW 12೥4݄18೔ਫ༵೔
6. JMX JMX provides probe for JVM JDK contains tools to use JMX jconsole VisualVM We can create original reporters 12೥4݄18೔ਫ༵೔
7. Abstract 12೥4݄18೔ਫ༵೔
8. CPU time 12೥4݄18೔ਫ༵೔
9. Java Heap 12೥4݄18೔ਫ༵೔
10. Class loader Class loader has a parent CL may have some child CL loads class if its parent doesn’t have it (default behavior) 12೥4݄18೔ਫ༵೔
11. How JVM calls CL public void main() { // To call static method, CL // gets class from Bootstrap CL Integer i = Integer.valueOf(0); // Bootstrap CL doesn’t have our // original class, so CL will // load it from .class OriginalClass.hello(i); } 12೥4݄18೔ਫ༵೔
12. Singletons in 1 JVM I loaded Singleton class and it has static field Really? My singleton class also has static field! 12೥4݄18೔ਫ༵೔
13. Summary You have to know GC and Java Heap to understand Java performance JMX is the easiest way to know issue Sometimes Class Loader creates complex bug 12೥4݄18೔ਫ༵೔
14. References Java virtual machine - Wikipedia From Java code to Java heap Java classes and class loading Visual VM 12೥4݄18೔ਫ༵೔