Memory Leaks
Agenda
- What are memory leaks?
- How do they get created?
- How can we detect them?
- How can we fix Them?
- Demo
- Best practices
Definition
"A type of resource leak that occurs when a computer program incorrectly manages memory allocations in such a way that memory which is no longer needed is not released." (Wikipedia)
Garbage Collection
- Mark And Sweep
- roots (window)
- Unmarked children are GC'ed
Types of Memory Leaks
The easy three:
- Accidental global variables
- Timers & Callbacks (watchers etc.)
- DOM reference from JavaScript
The complicated one:
- Closures
Periodic vs. Sporadic
Tools - Timeline
Record your app over time to view:
- JS Heap
- Documents
- Nodes
- Listeners
Find out leak trends.
Tools - Profiles
- Record heap snapshot
- Snapshot compression
- Shallow vs. Retained
- Yellow vs. Red
- The 3 snapshot check
- Record heap allocation over time
- Record allocation profile
Demo
Best Prectices
- 'use strict'
- Cancel timeouts\intervals\callbacks
- Remove DOM references
- Understand closure impact
- Name unanimous function & function expressions
- Separate short lived from long lived objects