IssueTracker

Indeed, since the disk IO can take more than 500ms, uses of the #apply method is now like scheduling a time bomb for ANR!

Obviously, the implementation of

  https://developer.android.com/reference/android/content/SharedPreferences.Editor#apply()

needs to be fixed so that the asynchronous commit to disk is never performed in the UI thread.

Apparently this bug has been around for a while, likely causing numerous ANR's across many applications:

  https://stackoverflow.com/questions/36905415/how-to-analyze-anr-in-sharedpreferences/52843655

Project: platform/frameworks/support
Branch: androidx-master-dev

commit 288afbcaeaf69c9f340e941154ed8aad05f0442e
Author: Sumir Kataria <sumir@google.com>
Date:   Wed Oct 17 11:24:33 2018

    Lazily load Preferences.
   
    Removes a potential disk IO on startup (which I haven't been able to
    actually get to trigger a strict mode violation).
   
    Changed integration test app to manually initialize WM.
   
    Bug: 117796731
    Test: Ran existing tests.
    Change-Id: Ie8c77b4145aeb8a2e9a0b05e0cb20881cf4abc7e

M       work/integration-tests/testapp/src/main/AndroidManifest.xml
A       work/integration-tests/testapp/src/main/java/androidx/work/integration/testapp/TestApplication.java
M       work/workmanager/src/main/java/androidx/work/impl/utils/Preferences.java

https://android-review.googlesource.com/792525
https://goto.google.com/android-sha1/288afbcaeaf69c9f340e941154ed8aad05f0442e

Thank you for the quick response!

If it helps, this is the strict mode violation stacktrace I get:

StrictMode policy violation; ~duration=94 ms: android.os.strictmode.DiskReadViolation
        at android.os.StrictMode$AndroidBlockGuardPolicy.onReadFromDisk(StrictMode.java:1504)
        at java.io.UnixFileSystem.checkAccess(UnixFileSystem.java:251)
        at java.io.File.exists(File.java:815)
        at android.app.ContextImpl.ensurePrivateDirExists(ContextImpl.java:605)
        at android.app.ContextImpl.ensurePrivateDirExists(ContextImpl.java:596)
        at android.app.ContextImpl.getPreferencesDir(ContextImpl.java:552)
        at android.app.ContextImpl.getSharedPreferencesPath(ContextImpl.java:747)
        at android.app.ContextImpl.getSharedPreferences(ContextImpl.java:400)
        at android.content.ContextWrapper.getSharedPreferences(ContextWrapper.java:174)
        at android.content.ContextWrapper.getSharedPreferences(ContextWrapper.java:174)
        at androidx.work.impl.utils.Preferences.<init>(Preferences.java:45)
        at androidx.work.impl.WorkManagerImpl.<init>(WorkManagerImpl.java:194)
        at androidx.work.impl.WorkManagerImpl.<init>(WorkManagerImpl.java:162)
        at androidx.work.impl.WorkManagerImpl.initialize(WorkManagerImpl.java:138)
        at androidx.work.WorkManager.initialize(WorkManager.java:158)
        at com.twofortyfouram.app.work.WorkSetup.setupWorkHelper(WorkSetup.java:70)
        at com.twofortyfouram.app.work.WorkSetup.setupWork(WorkSetup.java:59)
        at com.twofortyfouram.app.ApplicationImpl.onCreate(ApplicationImpl.java:89)
        at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1154)
        at android.app.ActivityThread.handleBindApplication(ActivityThread.java:5871)
        at android.app.ActivityThread.access$1100(ActivityThread.java:199)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1650)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

Reproduced with alpha 10.