[android-developers] Re: finish() at onStop causes ANR
It is true that the documentation does not specifically forbid calling
finish() from onStop(). But then what documentation does document ALL
the things you are not supposed to do? None that I know of.
Still, I have to suspect that TreKing is right, even if the
documentation does not clearly support him. This is because it is
really too clear that yours is an unexpected usage. Very unexpected.
Normally, one would never bother calling finish() from onStop(), since
1) that part of lifecycle management is already handled by the system,
which does well enough and 2) finish() does the same thing as pressing
the Back key, which of course can only happen while the Activity is in
the Foreground Process. Yet you are calling the finish() API from the
Background Process.
Again, this is no proof that it is wrong, just a strong indicator. But
that together with what you already showed, that the ANR happens from
mKeyWaiter implies that finish() really was expecting to still have
user input focus, which no Background Process has.
On Jul 31, 7:30 pm, James Wang jameswangc...@gmail.com wrote:
@TreKing
Thanks for your replies. We do have some reasons to call finish
because Android did not finish one when another is shown before it.Probably,
but with your code, not Android.
Document does not say finish is not allowed to be called at onStop.
How to explain there is no problem with calling finish just after
startActivity.
@Dianne
Thanks for your replies. We do believe it is a problem with framework.
WindowManagerService.java:
private int dispatchPointer(QueuedEvent qev, MotionEvent ev, int
pid, int uid) {
if (DEBUG_INPUT || WindowManagerPolicy.WATCH_POINTER)
Log.v(TAG,
dispatchPointer + ev);
if (MEASURE_LATENCY) {
lt.sample(3 Wait for last dispatch , System.nanoTime() -
qev.whenNano);
}
Object targetObj = mKeyWaiter.waitForNextEventTarget(null,
qev,
ev, true, false, pid, uid);
When calling finish() after startActivity,
mKeyWaiter.waitForNextEventTarge returns activity A. And after
checking A.isVisibleLW(), the key up event is discarded successfully.
When calling finish() at onStop, ANR happens in
mKeyWaiter.waitForNextEventTarge and it is seems never get out.
James
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Re: [android-developers] Re: finish() at onStop causes ANR
Again, get the stack crawls. This discussion is fairly pointless without at
least having the stack crawls of the app when it ANRed.
As for calling finish() in onStop() -- you can call finish() at any time.
(Well, not after onDestroy().) And in fact it would be hard for doing this
in onStop() to directly cause an ANR, since by this time the activity that
is executing onStop() no longer has input focus so *can't* ANR because of
something happening then.
mKeyWaiter.waitForNextEventTarget not returning... well, yeah, that is what
happens when there is an ANR. The window manager has dispatched an event,
is waiting for the application to process it, and ends up waiting for more
than 5 seconds. ANR. That's what that function is doing.
On Sat, Jul 31, 2010 at 7:30 PM, James Wang jameswangc...@gmail.com wrote:
@TreKing
Thanks for your replies. We do have some reasons to call finish
because Android did not finish one when another is shown before it.
Probably, but with your code, not Android.
Document does not say finish is not allowed to be called at onStop.
How to explain there is no problem with calling finish just after
startActivity.
@Dianne
Thanks for your replies. We do believe it is a problem with framework.
WindowManagerService.java:
private int dispatchPointer(QueuedEvent qev, MotionEvent ev, int
pid, int uid) {
if (DEBUG_INPUT || WindowManagerPolicy.WATCH_POINTER)
Log.v(TAG,
dispatchPointer + ev);
if (MEASURE_LATENCY) {
lt.sample(3 Wait for last dispatch , System.nanoTime() -
qev.whenNano);
}
Object targetObj = mKeyWaiter.waitForNextEventTarget(null,
qev,
ev, true, false, pid, uid);
When calling finish() after startActivity,
mKeyWaiter.waitForNextEventTarge returns activity A. And after
checking A.isVisibleLW(), the key up event is discarded successfully.
When calling finish() at onStop, ANR happens in
mKeyWaiter.waitForNextEventTarge and it is seems never get out.
James
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Dianne Hackborn
Android framework engineer
hack...@android.com
Note: please don't send private questions to me, as I don't have time to
provide private support, and so won't reply to such e-mails. All such
questions should be posted on public forums, where I and others can see and
answer them.
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[android-developers] Re: finish() at onStop causes ANR
@TreKing
Thanks for your replies. We do have some reasons to call finish
because Android did not finish one when another is shown before it.
Probably, but with your code, not Android.
Document does not say finish is not allowed to be called at onStop.
How to explain there is no problem with calling finish just after
startActivity.
@Dianne
Thanks for your replies. We do believe it is a problem with framework.
WindowManagerService.java:
private int dispatchPointer(QueuedEvent qev, MotionEvent ev, int
pid, int uid) {
if (DEBUG_INPUT || WindowManagerPolicy.WATCH_POINTER)
Log.v(TAG,
dispatchPointer + ev);
if (MEASURE_LATENCY) {
lt.sample(3 Wait for last dispatch , System.nanoTime() -
qev.whenNano);
}
Object targetObj = mKeyWaiter.waitForNextEventTarget(null,
qev,
ev, true, false, pid, uid);
When calling finish() after startActivity,
mKeyWaiter.waitForNextEventTarge returns activity A. And after
checking A.isVisibleLW(), the key up event is discarded successfully.
When calling finish() at onStop, ANR happens in
mKeyWaiter.waitForNextEventTarge and it is seems never get out.
James
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