Memory Management in Android

In this talk I discuss the following :

How android manages memory .
Evaluating application memory .
How to reduce application memory usage .

Transcript

1. Memory Management in Android Rajesh Khetan
2. AGENDA • How android manages memory • Evaluating application memory • How to reduce application memory usage
3. Android Memory Management KERNEL SPACE (1GB) USER SPACE (3GB) 4GB
4. Android Memory Management • Android uses paging and memory-mapping . • Extensive use of shared memory • Framework code and resources • Most static data(Dalvik code , app resources , .so files) is mmapped into a process. • Android shares the same dynamic RAM across processes using explicitly allocated shared memory regions.
5. Low memory killer • Kernel module. • Moves task of managing out of memory (oom) issues to the user space • It does this by allowing the user-space to maintain a list of adjustments and a corresponding list of thresholds (units are in memory pages - usually 4K) at which point processes with these adjustments should be killed. • The actually killing of process is done by the lowmemorykiller
6. Low memory killer • ActivityManagerService is responsible to update the adjustments (oom_adj) to processes continuously. • Lower value has higher priority • Range is from -17 (not killable) to 15 (hidden/cached apps) • System process runs at -16
7. Process Types
8. Process Types NATIVE Init , installd , serviceregistry , adbd
9. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server
10. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth
11. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to
12. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app
13. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user.
14. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE Process not being directly interacted by user like music app , keyboard
15. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE Process not being directly interacted by user like music app , keyboard SERVICE A Process running background services which are recently started
16. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE Process not being directly interacted by user like music app , keyboard SERVICE A Process running background services which are recently started HOME Launcher application process
17. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE Process not being directly interacted by user like music app , keyboard SERVICE A Process running background services which are recently started HOME Launcher application process PREVIOUS Last used application process
18. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE Process not being directly interacted by user like music app , keyboard SERVICE A Process running background services which are recently started HOME Launcher application process PREVIOUS Last used application process SERVICE B Process running background services since long time.
19. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE Process not being directly interacted by user like music app , keyboard SERVICE A Process running background services which are recently started HOME Launcher application process PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
20. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE Process not being directly interacted by user like music app , keyboard SERVICE A Process running background services which are recently started HOME Launcher application process PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
21. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE Process not being directly interacted by user like music app , keyboard SERVICE A Process running background services which are recently started HOME Launcher application process PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
22. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE Process not being directly interacted by user like music app , keyboard SERVICE A Process running background services which are recently started HOME Launcher application process PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
23. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE Process not being directly interacted by user like music app , keyboard SERVICE A Process running background services which are recently started HOME Launcher application process WALLPAPER GONE !! PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
24. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE Process not being directly interacted by user like music app , keyboard SERVICE A Process running background services which are recently started HOME Launcher application process WALLPAPER GONE !! PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
25. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE MUSIC GONE!! SERVICE A Process running background services which are recently started HOME Launcher application process WALLPAPER GONE !! PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
26. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE MUSIC GONE!! SERVICE A Process running background services which are recently started HOME Launcher application process WALLPAPER GONE !! PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
27. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE MUSIC GONE!! SERVICE A Process running background services which are recently started HOME Launcher application process WALLPAPER GONE !! PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
28. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE MUSIC GONE!! SERVICE A Process running background services which are recently started HOME Launcher application process WALLPAPER GONE !! PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
29. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE MUSIC GONE!! SERVICE A Process running background services which are recently started HOME Launcher application process WALLPAPER GONE !! PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
30. Process Types NATIVE Init , installd , serviceregistry , adbd SYSTEM System server DEVICE REBOOTS PERSISTENT telephony , wifi , buetooth PERSISTENT SERVICE This is a process that the system or a persistent process has bound to FOREGROUND This is the process running the current foreground app VISIBLE hosting only activities that are visible to the user. PERCEPTIBLE MUSIC GONE!! SERVICE A Process running background services which are recently started HOME Launcher application process WALLPAPER GONE !! PREVIOUS Last used application process SERVICE B Process running background services since long time. CACHED Other process which you can see in the recent apps
31. Memory Management For Applications
32. Why memory management for applications ? OEMS
33. Why memory management for applications LOW RANGE (LOW MEMORY) MID RANGE PREMIUM (HIGH MEMORY) OEMS
34. Why memory management for applications LOW RANGE (LOW MEMORY) MID RANGE PREMIUM (HIGH MEMORY) OEMS
35. Why memory management for applications LOW RANGE (LOW MEMORY) MID RANGE PREMIUM (HIGH MEMORY) OEMS APPLICATIONS
36. Why memory management for applications LOW RANGE (LOW MEMORY) MID RANGE PREMIUM (HIGH MEMORY) OEMS APPLICATIONS
37. Why memory management for applications MID RANGE PREMIUM (HIGH MEMORY) OEMS APPLICATIONS
38. Why memory management for applications MID RANGE PREMIUM (HIGH MEMORY) OEMS APPLICATIONS
39. Application Memory • Restricted application memory (dalvik.vm.heapgrowthlimit) • getMemoryClass() • Large memory applications (dalvik.vm.heapsize) • android:largeHeap=“true” in mainfest • getLargeMemoryClass();
40. Measuring Application Memory SYSTEM APP 2 APP 1 GOOGLE PLAY SERVICES RAM
41. # Pages used by the application ? NO Processes share memory , which process is accountable for that ?
42. Parameters Virtual Set Size(VSS) #pages accessible by a process.
43. Parameters Resident Set Size(RSS) Physical memory currently allocated and used by a process . App is completely responsible for shared pages.
44. Parameters Proportional Set Size(PSS) App is proportionally responsible for shared pages. Private pages : 2 Private pages used by 2 other process : 6 PPS = 2 + 6/3 = 4
45. Parameters Unique set size(USS) #unique pages associated with a process.
46. Parameters VSS > RSS > PSS >USS
47. Tools for memory management
63. Other tools • Memory Info api • showmap
64. How to reduce memory usage ? • Reduce Java Heap Memory • Optimize Images • Release Memory when Android asks for more memory • Use specific containers . • Favor static inner classes over non-static
65. How to reduce memory usage ? • Reduce your apk size • Things that take space in your APK tend to take memory at runtime too • Resources , bitmaps , .so files etc. • 3rd party libraries • Use App Bundle
66. THANK YOU References : • Google IO ‘18 Android memory usage(https://www.youtube.com/watch?v=w7K0jio8afM) • Source.android.com • StackOverflow.com • https://developer.android.com/topic/performance/memory-overview