Quartz 4

Demystifying JVM Memory Management

1 min read

Source: https://foojay.io/today/demystifying-jvm-memory-management/

JVM memory structure

Heap

  • This is where JVM store dynamic data.
  • Biggest block of memory area and this is where GC takes place.
  • The size of heap memory can be controlled in Xms (Initial) and Xmx (max) flags.
  • The entire heap memory is not committed to the Virtual Machine (VM) as some of it is reserved as virtual space and the heap can grow to use this.
  • Divided into “Young” and “Old” generation.
Young generation
  • Also called “New Space”, this is where new objects live and further divided into “Eden Place” and “Survivor Space”.
  • Managed by “Minor GC” or “Young GC”.
    • “Eden Space”: this is where new objects created. When we can create a new object, memory is allocated here.
    • “Survivor Space”: This is where objects that survived the minor GC are stored, divided in two halves, S0 and S1.
Old generation

Graph View

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