837426 - java.lang.NullPointerException: at org.mozilla.gecko.TabsTray$TabsAdapter.getView(TabsTray.java)

Status: RESOLVED INCOMPLETE

(Firefox for Android Graveyard :: General, defect)

Description

[Scoobidiver (away)]

There are one crash in 20.0a2 and one crash in 21.0a1: bp-8f159d03-e813-4309-93fc-007a92130202.

java.lang.NullPointerException
	at org.mozilla.gecko.TabsTray$TabsAdapter.getView(TabsTray.java:263)
	at android.widget.AbsListView.obtainView(AbsListView.java:2033)
	at android.widget.ListView.makeAndAddView(ListView.java:1772)
	at android.widget.ListView.fillUp(ListView.java:705)
	at android.widget.ListView.fillGap(ListView.java:645)
	at android.widget.AbsListView.trackMotionScroll(AbsListView.java:4546)
	at android.widget.AbsListView.scrollIfNeeded(AbsListView.java:2852)
	at android.widget.AbsListView.onTouchEvent(AbsListView.java:3106)
	at android.view.View.dispatchTouchEvent(View.java:5545)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1951)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1712)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1957)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1726)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1957)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1726)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1957)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1726)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1957)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1726)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1957)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1726)
	at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1957)
	at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1726)
	at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1912)
	at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1371)
	at android.app.Activity.dispatchTouchEvent(Activity.java:2391)
	at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1860)
	at android.view.View.dispatchPointerEvent(View.java:5725)
	at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:2928)
	at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2492)
	at android.view.ViewRootImpl.processInputEvents(ViewRootImpl.java:870)
	at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2501)
	at android.os.Handler.dispatchMessage(Handler.java:99)
	at android.os.Looper.loop(Looper.java:137)
	at android.app.ActivityThread.main(ActivityThread.java:4424)
	at java.lang.reflect.Method.invokeNative(Native Method)
	at java.lang.reflect.Method.invoke(Method.java:511)
	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
	at dalvik.system.NativeStart.main(Native Method)

More reports at:
https://crash-stats.mozilla.com/report/list?signature=java.lang.NullPointerException%3A+at+org.mozilla.gecko.TabsTray%24TabsAdapter.getView%28TabsTray.java%29

Comment 1

[Chris Peterson [:cpeterson]]

Sriram, TabsAdapter.mTabs is null here. Is this a race condition when closing tabs or shutting down?

https://hg.mozilla.org/mozilla-central/annotate/2360c3c46aca/mobile/android/base/TabsTray.java#l263

Comment 2

[Mark Finkle (:mfinkle) (use needinfo?)]

We seem to be null checking mTabs in other places in the file, even setting mTabs = null in clear. Do we need to null check in getView() ? What would the correct action be in that case? Skip the assignValues call? Check at the top of getView and return null (seems like a bad idea)?

getItem is not protected either:
https://hg.mozilla.org/mozilla-central/annotate/2360c3c46aca/mobile/android/base/TabsTray.java#l208

Comment 3

[Sriram Ramasubramanian [:sriram]]

The case where this could happen is, "there are 10 tabs, the tabs tray is opened, and closed swiftly". In this case, we start rendering tab rows, and then a hide() is called which clears the data. I guess we need to lock on mTabs.

getView() will be called only if getCount() returns a positive value. And between getCount() and getView(), we are calling hide() (but how? hide() is not running on UI thread??).

If we ensure hide() is called on UI thread, we won't have a problem here I guess.

Comment 4

[Sriram Ramasubramanian [:sriram]]

Is there any STR?

Comment 5

[Kevin Brosnan [Ex-Mozilla]]

Crash signature does not show up on crash-stats any more.