Quite frequently due to memory leaks or other memory problems applications freeze leaving only the garbage collector (GC) process running unsuccessfully trying to free some space. This happens until watchdog (or frustrated administrator) restarts the application and the problem is never solved.
The goal of this article is to show how to identify excessive GC and to get a heap dump whenever it occurs. It assumes Hotspot JVM version 1.6 or higher.
Showing posts with label hotspot. Show all posts
Showing posts with label hotspot. Show all posts
Saturday, June 9, 2012
Monday, October 24, 2011
Just in Time Compiler (JIT) in Hotspot
What is JIT Compiler?
The Just In Time Compiler (JIT) concept and more generally adaptive optimization is well known concept in many languages besides Java (.Net, Lua, JRuby).
In order to explain what is JIT Compiler I want to start with a definition of compiler concept. According to wikipedia compiler is "a computer program that transforms the source language into another computer language (the target language)".
We are all familiar with static java compiler (javac) that compiles human readable .java files to a byte code that can be interpreted by JVM - .class files. Then what does JIT compile? The answer will given a moment later after explanation of what is "Just in Time".
The Just In Time Compiler (JIT) concept and more generally adaptive optimization is well known concept in many languages besides Java (.Net, Lua, JRuby).
In order to explain what is JIT Compiler I want to start with a definition of compiler concept. According to wikipedia compiler is "a computer program that transforms the source language into another computer language (the target language)".
We are all familiar with static java compiler (javac) that compiles human readable .java files to a byte code that can be interpreted by JVM - .class files. Then what does JIT compile? The answer will given a moment later after explanation of what is "Just in Time".
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