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Memory Management in Android
Hirbod Kamalinia Keyhan Asghari
Why?
• OutOfMemoryError
• Bad user experiences
• Lags
• ...
Memory Structure
Memory Structure
Memory Handling
• C++, manual handling
• Java, Garbage Collection
• Android, Improved GC
Garbage CollectionGC Roots
Garbage CollectionGC Roots
Garbage CollectionGC Roots
Garbage CollectionGC Roots
Garbage CollectionGC Roots
Everything OK?
NO!
Remaining Problems?
• Memory Churn
• Memory Leak
Memory LeakGC Roots
Memory LeakGC Roots
How?
• Concepts
• Useful Tools
Objects in Heap
• Shallow Heap
• Retained Heap
Shallow heap & Retained heap
Shallow heap & Retained heap
100
100
100
100
Shallow heap & Retained heap
100
100
100
100
Shallow heap & Retained heap
100
100
100
100
Retained = 100
Shallow heap & Retained heap
100
100
100
100
Shallow heap & Retained heap
100
100
100
100
Retained = 100
Shallow heap & Retained heap
100
100
100
100
Shallow heap & Retained heap
100
100
100
100
Shallow heap & Retained heap
100
100
100
100
Retained = 100 + 100
Shallow heap & Retained heap
100
100
100
100
Retained = 200
Shallow heap & Retained heap
100
100
100
100
Shallow heap & Retained heap
100
100
100
100Retained = 100+ 100+ 100+ 100
Shallow heap & Retained heap
100
100
100
100Retained = 400
Dominator Tree
How to find these relations?
Dominator Tree
A
C
B
E
D
Dominator: closest object on every path to node
A
B DC
E
Useful Tools
• Android Studio Memory Monitor
• DDMS Heap tools and Allocation Tracker
• Eclipse Memory Analyzer (MAT)
• ...
Android Studio Memory Monitor
Android Studio Memory Monitor
Free and Allocated Memory
Android Studio Memory Monitor
GC Executions
Android Studio Memory Monitor
Memory Allocation Level ChangedMemory Allocation Level Changed
Android Studio Memory Monitor
Call GC Explicitly
Android DDMS
Android DDMS
Useful Tools!
Android DDMS
Call GC Explicitly
Android DDMS
Dump Java Heap
Eclipse Memory Analyzer (MAT)
DEMO...
What NOT to do?• Static References
• Inner Classes
• Reference to Context
• Adapters
• ....
Memory matters!
Thanks for your interest...
Useful links
• http://goo.gl/xb57Df
• http://goo.gl/o5O2ON
• http://goo.gl/8BqmCB
