Think Async: Understanding the Complexity of Multithreading - Avi Kabizon & Amichai Nitzan
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This document discusses asynchronous programming patterns in Android. It begins with an introduction to concurrency and why it is important for user experience. Common async patterns in Android like AsyncTask, Loader, HandlerThread and IntentService are described. Real world examples demonstrate how these patterns are used for network calls and updating the UI. The presentation emphasizes optimizing UI performance and animations. It concludes by encouraging developers to think asynchronously to improve apps.
![Think Async
19
Method
Network
Sleep/Wait
Scale:
Main
com.kayak.android.car.CarActivity$5.onClick
com.kayak.android.car.CarResultFragment.onCreateV
iew()
com.kayak.android.currency.CurrencyController.lock(
)
[POST]https://www.kayak.com/s/impression/inline
UI finished rendering](https://image.slidesharecdn.com/hpe-thinkaboutasyncdroidconfinal-161009122449/85/Think-Async-Understanding-the-Complexity-of-Multithreading-Avi-Kabizon-Amichai-Nitzan-19-320.jpg)
![Think Async - Network
Make a network call. Process the result and update UI.
com.amazon.mShop.home.HomeView$2.onClick()
com.amazon.rio.j2me.client.util.Worker.run()
[POST] https://msh.amazon.com/mShop/service
com.amazon.mShop.categoryBrowse.CategoryBrowseActivity.onResume()
com.amazon.mShop.MShopActivity.onResume()
com.amazon.mShop.android.AmazonActivity.onResume()
…
com.amazon.mShop.android.AmazonActivity$1.onAnimationStart()
com.amazon.mShop.android.AmazonActivity$1.onAnimationEnd()
…
com.amazon.mShop.categoryBrowse.CategoryBrowseMainPageView$CategoryMainViewAdapter.g
Main
User action: Open Shop by department activity](https://image.slidesharecdn.com/hpe-thinkaboutasyncdroidconfinal-161009122449/85/Think-Async-Understanding-the-Complexity-of-Multithreading-Avi-Kabizon-Amichai-Nitzan-22-320.jpg)
![Think Async - Network
Thread per HTTP call
com.amazon.mShop.android.net.HttpFetcher.run()
[GET] http://ecx.images-amazon.com/images/I/51wxjlaS0qL._SL360_.jpg
Method
Network
Sleep/Wait
Scale:
Main
User action: Browse by category
foreach (resource to download) {
startAsyncTask(resource)
}](https://image.slidesharecdn.com/hpe-thinkaboutasyncdroidconfinal-161009122449/85/Think-Async-Understanding-the-Complexity-of-Multithreading-Avi-Kabizon-Amichai-Nitzan-28-320.jpg)
Think Async: Understanding the Complexity of Multithreading - Avi Kabizon & Amichai Nitzan
- 1. Think About Async Think Async Understanding the Complexity of Multi-Threading
- 2. Who Are We? Avi Kabizon @avikabizon R&D Team Manager AppPulse Mobile R&D avi.kabizon@hpe.com Amichai Nitsan @aminits Senior Architect AppPulse Suite R&D amichai.nitsan@hpe.com
- 3. . . . Our Day Job . . . –User Experience Monitoring: Performance Stability Usage Resource utilization –Tag-less and codeless –SaaS based, Free trial 3 saas.hpe.com/en-us/software/AppPulse-mobile
- 4. 4 Motivation Async Patterns in Android Real World Examples Summary Agenda
- 5. Motivation Concurrency And Android Programming 5
- 6. 6 Why Waiting Is Torture Alex Stone AUG. 18, 2012 http://www.nytimes.com/2012/08/19/opinion/sunday/why-waiting-in-line-is-torture.html
- 7. Why Concurrency? 7 It is all about the User Experience Processing of data Waiting for server Housekeeping
- 8. Android and Concurrency Pretty sure you all know but… – The UI thread is not allowed to access the network (a crash in StrictMode) … But also other long tasks are not allowed – Avoid the dreadful “Application Not Responding” (ANR) dialog: – Respond to a user action whithin 5 seconds – Finish executing a BroadcastReceiver within 10 seconds 8
- 9. Android Application Responsiveness – An application should respond to any user action within 100 - 200 ms – “response” ≠ work is done – Indicate that “work is being done, and there is progress” but entertain the users while they wait Make sure every user action is handled as fast as possible Users appreciate if you “take notes” and continue to serve them – Think Async: – Do users really need to wait for this image to upload? – Can the users start working with partial data? – Is the screen rendering waiting for unrelated actions? 9
- 10. Thread Performance Isolation 10 – How are threads behaving? – Challenges with existing tools: – Debugger – Logs (System.err.println) – Traceview: – Capture button – Code tagging (android.os.Debug.startMethodTracing)
- 11. Async Patterns In Android #PERFMATTERS @YouTube 11
- 12. AsyncTask – Easy to use – Short tasks that update the UI – Tied to fragment or activity lifecycle – Android executes AsyncTask tasks serially by default 12 class AsyncTask // init UI onPreExecute() // start background doInBackground() // update UI onProgressUpdate() // Update UI onPostExecute() task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, params);
- 13. Loader 13 class CursorLoader // returns a cursor public Cursor loadInBackground() – Loads data from an external source into a local DB – Ideal for sync that is independent of user actions – Not tied to fragment or activity – Complex to use in code
- 14. HandlerThread – A background thread for handling multiple jobs in the background – Runs outside of activity lifecycle – Long running processes – Need to manage lifecycle manually - call quit() – No built-in mechanism for reporting back – Set the right thread priority! 14 HandlerThread handlerThread = new HandlerThread("MyHandlerThread"); handlerThread.start(); Looper looper = handlerThread.getLooper(); Handler handler = new Handler(looper); … handler.post(new Runnable(){…});
- 15. IntentService – HandlerThread runs as a Service – Handles incoming Intents on a separate process – Best for intents without foreground updates – Will block other incoming intents 15 class IntentService // Do work here onHandleIntent(Intent workIntent) <application> <service android:name=".MyService" android:exported="false"/> <application/>
- 16. ThreadPoolExecutor – Manages a pool of worker threads – Tasks run in parallel – Powerful tool for demanding situations – Each thread consumes at least 64KB of mem – Need to find the magical min and max number of threads 16 ThreadPoolExecutor executor = new ThreadPoolExecutor(); executor.execute(new Runnable() { public void run() { // Do some long running } });
- 17. Java Thread – Fine control on the details … but lots of code – Usually used as last resort 17 new Thread(new Runnable() { public void run() { // do background job } }).start(); JobScheduler SyncAdapter
- 18. ThinkAsync – The Real World 18
- 20. Think Network - Real world examples 20
- 21. Think Async - Network Make a network call. No subsequent UI update. onclick() Network call Main doInbackground() User action: Submit registration form
- 22. Think Async - Network Make a network call. Process the result and update UI. com.amazon.mShop.home.HomeView$2.onClick() com.amazon.rio.j2me.client.util.Worker.run() [POST] https://msh.amazon.com/mShop/service com.amazon.mShop.categoryBrowse.CategoryBrowseActivity.onResume() com.amazon.mShop.MShopActivity.onResume() com.amazon.mShop.android.AmazonActivity.onResume() … com.amazon.mShop.android.AmazonActivity$1.onAnimationStart() com.amazon.mShop.android.AmazonActivity$1.onAnimationEnd() … com.amazon.mShop.categoryBrowse.CategoryBrowseMainPageView$CategoryMainViewAdapter.g Main User action: Open Shop by department activity
- 23. Think Async - Network Pattern analysis User action: Search cars
- 24. Think Async - Network Pattern analysis onPostExecute() { … startAsyncTask(download); } User action: Search cars
- 25. Think Async - Network “Stairs” pattern analysis • Creates new async task during onPostExecute() • No parallelism of HTTP calls • Thread creation overhead
- 26. 26 Think Async - Network Handler thread User action: Open main activity Handler thread while (callable queue not empty) { runCallable (queue.poll); }
- 27. 27 Think Async - Network Handler thread User action: Open main activity • Single thread performs multiple HTTP calls on same method • No thread creation overhead • Easier to make fewer HTTP calls
- 28. Think Async - Network Thread per HTTP call com.amazon.mShop.android.net.HttpFetcher.run() [GET] http://ecx.images-amazon.com/images/I/51wxjlaS0qL._SL360_.jpg Method Network Sleep/Wait Scale: Main User action: Browse by category foreach (resource to download) { startAsyncTask(resource) }
- 29. Think Async - Network Thread per HTTP call Parallelization of HTTP calls New thread for each HTTP call
- 30. 30 Think Async - Network Thread pool Reused Threads User action: Open main tab
- 31. Think Async - Network Thread pool Parallelization of http calls Efficient reuse of threads
- 32. ThinkAsync – UI and Data 32
- 33. Think UI Keep smooth UI by avoiding frame loss • Most Android devices refresh the screen 60 times a second • That means your code running on the UI thread has only ~16ms to: • Measure • Layout • Draw • Keep UI thread only for UI • Remember that all the on* methods run inside the UI Thread
- 34. Think UI Speed up scrolling • Use Loaders • Use libraries, for example Glide or Picasso for image loading • Use RecyclerView or ListView with view holder pattern to avoid findViewById() calls
- 35. Think UI Optimize animations • Avoid layout or inflation during animation • Watch out for lifecycle events • Avoid initiating animations in onCreate, onStart or onResume. • Initiate animations on user events such as onClick and disable touch events until animation is complete. • Don't initiate more than 2 animations simultaneously
- 36. Think UI Animations in Think Async Fade in animation Shrink and grow animation Fragment.onResum e() Shrink and grow animation Fade in animation Layout change between animations Without layout change between animations
- 37. Wrap Up 37
- 39. Fighting to save the Digital User Experience Follow the adventures of the UX-Men: • AppPulse Active • AppPulse Mobile • AppPulse Trace 90% 1/3 saas.hpe.com/en-us/software/AppPulse-mobile