Finding what violated StrictMode policy

Question

I've enabled StrictMode in my app and it's causing a few crashes as expected. How can I find out where in my code I'm violating these policies?

This is the stack trace:

E/AndroidRuntime(19523): FATAL EXCEPTION: main
E/AndroidRuntime(19523): android.os.StrictMode$StrictModeViolation: policy=95 violation=2
E/AndroidRuntime(19523):        at android.os.StrictMode.executeDeathPenalty(StrictMode.java:1326)
E/AndroidRuntime(19523):        at android.os.StrictMode.access$1300(StrictMode.java:111)
E/AndroidRuntime(19523):        at android.os.StrictMode$AndroidBlockGuardPolicy.handleViolation(StrictMode.java:1319)
E/AndroidRuntime(19523):        at android.os.StrictMode$AndroidBlockGuardPolicy$1.run(StrictMode.java:1206)
E/AndroidRuntime(19523):        at android.os.Handler.handleCallback(Handler.java:605)
E/AndroidRuntime(19523):        at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime(19523):        at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime(19523):        at android.app.ActivityThread.main(ActivityThread.java:4424)
E/AndroidRuntime(19523):        at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(19523):        at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(19523):        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
E/AndroidRuntime(19523):        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
E/AndroidRuntime(19523):        at dalvik.system.NativeStart.main(Native Method)

but as you can see ... it's not very useful ... I know who killed my app, I need to know why!

Thanks.

Hyperbaric

How did you enable SrictMode? Please paste the code so we can inspect it. – Hyehyena

DetectAll.penaltyLog().penaltyDeath() for both. Looking at your response below, it just looks like I need to add "StrictMode" to my log filters :) – Hyperbaric

Answer 1

You need to call penaltyLog() on your StrictMode.ThreadPolicy.Builder, so that it will show you the underlying reason as well as stopping your app.

Here's what you probably have currently:

StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
.detectDiskReads()
.detectDiskWrites()
.detectNetwork()
.penaltyDeath()
.build());

If you call the network on the main thread, you'll get this exception which is hard to understand:

E/AndroidRuntime(8752): android.os.StrictMode$StrictModeViolation: policy=71 violation=4
E/AndroidRuntime(8752):     at android.os.StrictMode.executeDeathPenalty(StrictMode.java:1311)

If you then add penaltyLog() to your policy...

StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()
.detectDiskReads()
.detectDiskWrites()
.detectNetwork()
.penaltyLog()
.penaltyDeath()
.build());

then you will see a much more helpful message like the one below. This will be in the LogCat output.

D/StrictMode(8810): StrictMode policy violation; ~duration=2956 ms: android.os.StrictMode$StrictModeNetworkViolation: policy=87 violation=4
D/StrictMode(8810):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1090)

If you look closely, you'll see that this stack trace will lead you to the code which is causing the StrictMode violation.

Hyehyena

Note: This IS what I'm doing, but your log entry showed me that I need to adjust my log filters (which is what I was suspecting while trying to fall asleep :) ). You win the cake :) Thanks – Hyperbaric

Well, it doesn't look more helpful to me. How do I know what code it crashes on? – Garver

How closely should I look? Even after using the microscope, I don't see any helpful message yet. – Intermission

Answer 2

Whenever I see stack traces like this I always look into my Activity lifecycle events. Checkout what's going on in your onCreate, onResume, onPause methods (there are more lifecycle events but these are the common ones). Put break points in those methods and see which one terminates with this fatal message. Then take it from there.

Try catching this error using

protected void onResume() {
  super.onResume();
  try {
    codeThatCrashesBecauseOfStrictMode();
  } catch(Throwable tr) { Log.e(tr); }
}

This should be a pretty good starting point for debugging this problem.

Salman

Answer 3

StrictMode (android.os.StrictMode) class can be used to enable and enforce various policies that can be checked for and reported upon.

This can be a StrictMode violation in executing a disk write violation that occurs when you are performing disk writes on the main UI thread. To solve it, you need to move the disk writes off the main thread.

If you can't move the code at this point, you could disable the check for a part of the code.

Explicitly add code to stop checking for a particular rule violation just before the offending code is executed and then re-enable detection for that rule after the offending code has completed.

StrictMode.ThreadPolicy old = StrictMode.getThreadPolicy();
StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder(old)
    .permitDiskWrites()
    .build());
doCorrectStuffThatWritesToDisk();
StrictMode.setThreadPolicy(old);

Source code taken from here.

Inclement

I think you should reference the answer you took that code from: https://mcmap.net/q/506319/-strictmodediskreadviolation-when – Coneflower

Answer 4

even though this does nothing to understand root cause, would it help you to simply add "strict=False" to your Library definition? (note that my context is Robot Framework *** Settings *** where I include "Browser" library): eg:

Library     Browser     strict=False

Sternberg

Making it not crash without actually fixing the root cause defeats the purpose. – Hyperbaric