from the Samsung Developer Office Hours NYC

1. Samsung Developer Office Hours NYC
X Means Y:
Interpreting the
Development Tools
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2. 01-03 01:32:11.986: E/AndroidRuntime(17991):
Caused by: android.os.NetworkOnMainThreadException
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3. StrictMode
● Reports obvious long-running stuff on main
application thread
● Network I/O automatically reported on
Android 3.0+
– Do not disable the error – fix the problem!
– Opt-in for Android 2.3
● Can also configure to report disk I/O on main
thread, failure to close files/databases/cursors,
etc. Copyright © 2012CommonsWare, LLC

4. Copyright © 2012CommonsWare, LLC

5. 06-29 23:11:17.796: I/Choreographer(691):
Skipped 18 frames! The application may be doing
too much work on its main thread.
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6. Choreographer
● Information Message in LogCat
– “Skipped N frames” * 16ms = amount of time
you took on main application thread
– The more frames skipped, the more likely it is
the user will notice
● UI frozen and not responsive
● Animation/scrolling hiccups
– Android 4.1+
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7. Project Butter
● UI Updates @ 60 frames/second
● Objective: smoother UI updates
– Especially animations
● Transparent to developers
– No code changes to “opt into” Butter effects
● Google I/O 2012: “For Butter or Worse”
Copyright © 2012CommonsWare, LLC

8. Project Butter Ramifications
● Only ~16ms Per Frame
– Your code on the main application thread
– Framework code
– Other interruptions (e.g., background process)
● Net: Get Off the Main Application Thread!
– Anything taking more than a few milliseconds
needs to move to background thread or be
executed incrementally
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9. 12-12 08:56:20.746: E/AndroidRuntime(1570):
java.lang.RuntimeException: Can't create handler inside
thread that has not called Looper.prepare()
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10. Looper and Handler
● Queuing mechanism
● Used by main application thread
● Error results from trying to do wrong thing on
background thread
– setContentView()
– requestLocationUpdates()
● HandlerThread
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11. java.lang.StackOverflowError
at android.widget.TextView.onDraw(TextView.java:4329)
at android.view.View.draw(View.java:6993)
at android.view.ViewGroup.drawChild(ViewGroup.java:1732)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1459)
at android.view.View.draw(View.java:6996)
at android.view.ViewGroup.drawChild(ViewGroup.java:1732)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1459)
at android.view.View.draw(View.java:6996)
at android.view.ViewGroup.drawChild(ViewGroup.java:1732)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1459)
at android.view.View.draw(View.java:6996)
at android.view.ViewGroup.drawChild(ViewGroup.java:1732)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1459)
at android.view.View.draw(View.java:6996)
at android.view.ViewGroup.drawChild(ViewGroup.java:1732)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1459)
.
.
.
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12. StackOverflowError
● Your code?
– Too-deep recursion
● View/ViewGroup code?
– Too-complex UI: nested containers
– 8KB stack space on main application thread
Copyright © 2012CommonsWare, LLC

13. StackOverflowError
● Diagnostics
– Open UI in emulator
● Or device if you embed ViewServer in it
– Run Hierarchy View
● Eclipse perspective or via monitor
– Count depth
– Find stuff safe to eliminate
● Containers with only one child
Copyright © 2012CommonsWare, LLC

14. 07-13 10:42:23.820: E/AndroidRuntime(2065):
java.lang.OutOfMemoryError
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15. OutOfMemoryError
● Limited heap sizes
– 16-64MB, depending on OS version and device
capabilities
● Non-compacting garbage collector
– Cannot allocate a block big enough for your
request
● Primary culprit: bitmaps
– 1080p image = ~8MB
Copyright © 2012CommonsWare, LLC

16. OutOfMemoryError
● Diagnostics
– MAT
● Dump heap (HPROF) using Debug or DDMS
● Load into MAT (Eclipse plug-in or standalone)
● Hunt for culprits
– adb shell dumpsys meminfo
● Lots of low-level information
● Difficult to accurately interpret
Copyright © 2012CommonsWare, LLC

17. OutOfMemoryError
● BitmapFactory.Options
– inSampleSize: downsample for less heap use
– inPurgeable/inInputShareable: for sharing
backing data for mutations of common ancestor
bitmap
– inBitmap: for reusing existing Bitmap buffer
● Must be of the same dimensions and bit depth
● Maintain your own object pools versus
fragmenting your heap
Copyright © 2012CommonsWare, LLC

18. I/DEBUG (18110): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
I/DEBUG (18110): Build fingerprint: 'MOTO_O2DE/umts_sholes/umts_sholes/sholes:2.1-...
I/DEBUG (18110): pid: 23912, tid: 23913 >>> com.example.test <<<
I/DEBUG (18110): signal 11 (SIGSEGV), fault addr 0000000c
I/DEBUG (18110): r0 00140120 r1 00000048 r2 00000000 r3 00140168
I/DEBUG (18110): r4 afe3ae08 r5 00000006 r6 00140158 r7 0000a000
I/DEBUG (18110): r8 100ffcf8 r9 4185eef8 10 4185eee0 fp 001243b0
I/DEBUG (18110): ip 00000000 sp 100ffc50 lr afe0f130 pc afe0aeec cpsr 80000070
I/DEBUG (18110): #00 pc 0000aeec /system/lib/libc.so
I/DEBUG (18110): #01 pc 000008e6 /system/lib/libstdc++.so
I/DEBUG (18110): #02 pc 00014124 /system/lib/libutils.so
I/DEBUG (18110): #03 pc 0001423c /system/lib/libutils.so
I/DEBUG (18110): #04 pc 0001af28 /system/lib/libbinder.so
I/DEBUG (18110): #05 pc 0001ba20 /system/lib/libbinder.so
I/DEBUG (18110): #06 pc 0001bcd6 /system/lib/libbinder.so
I/DEBUG (18110): #07 pc 00014236 /system/lib/libutils.so
I/DEBUG (18110): #08 pc 000293a6 /system/lib/libandroid_runtime.so
I/DEBUG (18110): #09 pc 000313ca /system/lib/libandroid_runtime.so
I/DEBUG (18110): #10 pc 0000ecb4 /system/lib/libdvm.so
I/DEBUG (18110): #11 pc 00038838 /system/lib/libdvm.so
I/DEBUG (18110): #12 pc 000139b8 /system/lib/libdvm.so
I/DEBUG (18110): #13 pc 00019338 /system/lib/libdvm.so
I/DEBUG (18110): #14 pc 00018804 /system/lib/libdvm.so
.
.
.
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19. SIGSEGV
● Doing NDK development?
– Might be core dump from your code
● Repeatable across devices, or on Nexus?
– Probably a bug in Android
● Only happens on certain ROM?
– Probably a bug in the ROM mod
Copyright © 2012CommonsWare, LLC

20. Getting Help
● StackOverflow
– android tag
● Google Hangouts by Android Developer
Support
– QR code for YouTube archives
● www.andglobe.com
– Q&A sites, organized by language
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21. Speaker Contact
Information
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