ConcurrentModificationException in DelegatingWorkerFactory class [156289105]

Fixed

Bug

Status Update

No update yet.

Description

ul...@gmail.com

created issue #1

May 12, 2020 10:26AM

Component used: WorkManager Version used: 2.2.0 Devices/Android versions reproduced on: All versions

Stacktrace:

java.util.ConcurrentModificationException: null
    at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:966)
    at java.util.LinkedList$ListItr.next(LinkedList.java:888)
    at androidx.work.DelegatingWorkerFactory.createWorker(DelegatingWorkerFactory.java:66)
    at androidx.work.WorkerFactory.createWorkerWithDefaultFallback(WorkerFactory.java:81)
    at androidx.work.impl.WorkerWrapper.runWorker(WorkerWrapper.java:228)
    at androidx.work.impl.WorkerWrapper.run(WorkerWrapper.java:127)
    at androidx.work.impl.utils.SerialExecutor$Task.run(SerialExecutor.java:91)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
    at java.lang.Thread.run(Thread.java:764)

It seems that method addFactory of DelegatingWorkerFactory class tries to modify mFactories list while another thread is iterating over it.

Comments

ul...@gmail.com <ul...@gmail.com> #2May 12, 2020 10:28AM

Yigit, do you have time to fix it?

reemission of the same liveData is racy

ra...@google.com <ra...@google.com> #3May 12, 2020 04:30PM

yea i'll take it.

ra...@google.com <ra...@google.com> #4May 12, 2020 04:31PM

Thanks for the detailed analysis. This may not be an issue anymore since we've started using Main.immediate there but I' not sure; I'll try to create a test case.

ra...@google.com <ra...@google.com> May 12, 2020 06:07PM

Assigned to ra...@google.com.

ap...@google.com <ap...@google.com> #5May 12, 2020 11:37PM

Marked as fixed.

just emitting same live data reproduces the issue.

@Test
fun raceTest() {
val subLiveData = MutableLiveData(1)
val subject = liveData(testScope.coroutineContext) {
emitSource(subLiveData)
emitSource(subLiveData) //crashes
}
subject.addObserver().apply {
testScope.advanceUntilIdle()
}
}

ul...@gmail.com <ul...@gmail.com> #6May 13, 2020 08:59AM

With 2.2.0-alpha04 (that use Main.immediate), the issue seems to be still there (I tested it by calling emitSource() twice, like your test case)

Issue 156289105