I have written an app which displays html pages in Webviews, which are managed in a ViewPager. All working ok, but I have had a few ANRs when swiping from one page to another. The ANR data dump shows that the main thread has called through ThreadedRenderer.nSyncAndDrawFrame() which calls a native method, which apparently communicates with the Renderer thread, and waits for that thread to complete drawing the view. Since both of these are executing native code it's hard to work out what's going on but it appears the Renderer thread has never signalled the main thread to resume, hence causing the ANR. There is nothing in the logcat prior to the ANR report that suggests any problem.
Does anyone have suggestions for how to troubleshoot this? I am assuming that the call to ThreadedRenderer.nSyncAndDrawFrame() is associated with the Webview, but I don't actually have anything to confirm that.
The problem is not repeatable, in the sense that if I restart the app and navigate to the same page that was showing when the ANR occurred, it doesn't happen again. Device is a Nexus 7 running Android 5.1.
ANR stacktrace for main and renderer threads:
"main" prio=5 tid=1 Native
| group="main" sCount=1 dsCount=0 obj=0x73547000 self=0xb4827800
| sysTid=1248 nice=-6 cgrp=default sched=0/0 handle=0xb6fd6bec
| state=S schedstat=( 0 0 0 ) utm=6035 stm=1406 core=0 HZ=100
| stack=0xbe5a6000-0xbe5a8000 stackSize=8MB
| held mutexes=
kernel: (couldn't read /proc/self/task/1248/stack)
native: #00 pc 000133b8 /system/lib/libc.so (syscall+28)
native: #01 pc 00016a81 /system/lib/libc.so (__pthread_cond_timedwait_relative(pthread_cond_t*, pthread_mutex_t*, timespec const*)+56)
native: #02 pc 0003c73b /system/lib/libhwui.so (???)
native: #03 pc 0003c771 /system/lib/libhwui.so (???)
native: #04 pc 0083fd83 /data/dalvik-cache/arm/system@framework@boot.oat (Java_android_view_ThreadedRenderer_nSyncAndDrawFrame__JJJF+134)
at android.view.ThreadedRenderer.nSyncAndDrawFrame(Native method)
at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:340)
at android.view.ViewRootImpl.draw(ViewRootImpl.java:2530)
at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2352)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1982)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5885)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
at android.view.Choreographer.doCallbacks(Choreographer.java:580)
at android.view.Choreographer.doFrame(Choreographer.java:550)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke!(Native method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
"RenderThread" prio=5 tid=26 Native
| group="main" sCount=1 dsCount=0 obj=0x12c07820 self=0xa1c30800
| sysTid=1303 nice=-4 cgrp=default sched=0/0 handle=0xa1c44c00
| state=S schedstat=( 0 0 0 ) utm=8314 stm=1817 core=0 HZ=100
| stack=0xa0cc2000-0xa0cc4000 stackSize=1012KB
| held mutexes=
kernel: (couldn't read /proc/self/task/1303/stack)
native: #00 pc 000133b8 /system/lib/libc.so (syscall+28)
native: #01 pc 0001741b /system/lib/libc.so (__futex_wait_ex+42)
native: #02 pc 00017761 /system/lib/libc.so (pthread_mutex_lock+230)
native: #03 pc 0001d767 /system/vendor/lib/libgsl.so (os_mutex_lock+6)
native: #04 pc 0001ea88 /system/vendor/lib/egl/libEGL_adreno.so (egliDoDestroyEGLImage+180)
native: #05 pc 0008698d /system/vendor/lib/egl/libGLESv2_adreno.so (rb_image_try_release+32)
native: #06 pc 00086acf /system/vendor/lib/egl/libGLESv2_adreno.so (rb_destroy_resource_updates_pure+136)
native: #07 pc 00085491 /system/vendor/lib/egl/libGLESv2_adreno.so (rb_perform_resolve+276)
native: #08 pc 00085761 /system/vendor/lib/egl/libGLESv2_adreno.so (rb_resolve+464)
native: #09 pc 0008a891 /system/vendor/lib/egl/libGLESv2_adreno.so (rb_surface_swap+228)
native: #10 pc 0006af89 /system/vendor/lib/egl/libGLESv2_adreno.so (gl2_surface_swap+76)
native: #11 pc 0005d12b /system/vendor/lib/egl/libGLESv2_adreno.so (oglSwapBuffer+194)
native: #12 pc 00013ddc /system/vendor/lib/egl/libEGL_adreno.so (qeglDrvAPI_eglSwapBuffers+1776)
native: #13 pc 00007b60 /system/vendor/lib/egl/libEGL_adreno.so (eglSwapBuffers+16)
native: #14 pc 0001237f /system/lib/libEGL.so (eglSwapBuffers+290)
native: #15 pc 0003d291 /system/lib/libhwui.so (???)
native: #16 pc 0003bd05 /system/lib/libhwui.so (???)
native: #17 pc 0003beb5 /system/lib/libhwui.so (???)
native: #18 pc 0003caed /system/lib/libhwui.so (???)
native: #19 pc 0003e743 /system/lib/libhwui.so (android::uirenderer::renderthread::RenderThread::threadLoop()+66)
native: #20 pc 000104d5 /system/lib/libutils.so (android::Thread::_threadLoop(void*)+112)
native: #21 pc 0005f839 /system/lib/libandroid_runtime.so (android::AndroidRuntime::javaThreadShell(void*)+72)
native: #22 pc 00010045 /system/lib/libutils.so (???)
native: #23 pc 00016baf /system/lib/libc.so (__pthread_start(void*)+30)
native: #24 pc 00014af3 /system/lib/libc.so (__start_thread+6)
