JVM Architecture & Garbage Collection

Written by

Gaurav Wadhwani

Tech Learnings

JVM Architecture

$C:\Users\Gaurav\Downloads\java architecture\classloader.jpg$ class loader in detail

java memory areas

$C:\Users\Gaurav\Downloads\java architecture\runtime data areas.jpg$ runtime data areas – 2 covered out of 5

$C:\Users\Gaurav\Downloads\java architecture\runtime data areas 2.jpg$ runtime data areas rest 3

C:\Users\Gaurav\Downloads\java architecture\execeution engine.jpg

Execution engine

Garbage collection basic

C:\Users\Gaurav\Downloads\java architecture\garbage collection 2.jpg

compartments in heap

C:\Users\Gaurav\Downloads\java architecture\garbage collection 3.jpg

Eden space starts filling with object and ones in dark are marked for garbage collection

C:\Users\Gaurav\Downloads\java architecture\garbage collection 4.jpg

Post that the other objects in green are moved to Survivor1 space with an incremented count [for further decision on whether to put them in old gen or not]

$C:\Users\Gaurav\Downloads\java architecture\garbage collection 5.jpg$ Eden space is filled and again marking happen in all survivor spaces

C:\Users\Gaurav\Downloads\java architecture\garbage collection 6.jpg

They are then moved to another survivor space. This helps in compacting[if not done they will occupy non contiguous blocks in memory – similar to defragmentation ]