Component used:

Version used: Devices/Android versions reproduced on:

If this is a bug in the library, we would appreciate if you could attach:

Sample project to trigger the issue.
A screenrecord or screenshots showing the issue (if UI related).

Have migrated from paging 2.1.0 to 3.0.0, but are plagued by the "Channel was closed" exception when other (not paging 3.0 related code) is updating the Room db where the paging data is resided. This update may change the order in the resulting list also.

Is this due to Flow being used at the moment when the background process is updating data ? Room shoud be able to do this update and suspend/postpone/queue it until the Flow has done its updates to the UI.

Here is the errormessage:

2020-06-30 11:20:46.103 28114-28114/no.rogo.emptyfuel E/AndroidRuntime: FATAL EXCEPTION: main
    Process: no.rogo.emptyfuel, PID: 28114
    kotlinx.coroutines.channels.ClosedSendChannelException: Channel was closed
        at kotlinx.coroutines.channels.Closed.getSendException(AbstractChannel.kt:1035)
        at kotlinx.coroutines.channels.AbstractSendChannel.helpCloseAndResumeWithSendException(AbstractChannel.kt:206)
        at kotlinx.coroutines.channels.AbstractSendChannel.access$helpCloseAndResumeWithSendException(AbstractChannel.kt:19)
        at kotlinx.coroutines.channels.AbstractSendChannel.sendSuspend(AbstractChannel.kt:196)
        at kotlinx.coroutines.channels.AbstractSendChannel.send(AbstractChannel.kt:135)
        at kotlinx.coroutines.channels.ChannelCoroutine.send$suspendImpl(Unknown Source:2)
        at kotlinx.coroutines.channels.ChannelCoroutine.send(Unknown Source:0)
        at androidx.paging.PageFetcherSnapshot$pageEventFlow$1$2$invokeSuspend$$inlined$collect$1.emit(Collect.kt:137)
        at kotlinx.coroutines.flow.FlowKt__ChannelsKt.emitAllImpl$FlowKt__ChannelsKt(Channels.kt:58)
        at kotlinx.coroutines.flow.FlowKt__ChannelsKt$emitAllImpl$1.invokeSuspend(Unknown Source:11)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
        at kotlinx.coroutines.EventLoop.processUnconfinedEvent(EventLoop.common.kt:69)
        at kotlinx.coroutines.DispatchedTaskKt.resumeUnconfined(DispatchedTask.kt:184)
        at kotlinx.coroutines.DispatchedTaskKt.dispatch(DispatchedTask.kt:108)
        at kotlinx.coroutines.CancellableContinuationImpl.dispatchResume(CancellableContinuationImpl.kt:308)
        at kotlinx.coroutines.CancellableContinuationImpl.completeResume(CancellableContinuationImpl.kt:395)
        at kotlinx.coroutines.channels.AbstractChannel$ReceiveElement.completeResumeReceive(AbstractChannel.kt:872)
        at kotlinx.coroutines.channels.ConflatedChannel.offerInternal(ConflatedChannel.kt:61)
        at kotlinx.coroutines.channels.ConflatedBroadcastChannel$Subscriber.offerInternal(ConflatedBroadcastChannel.kt:293)
        at kotlinx.coroutines.channels.ConflatedBroadcastChannel.offerInternal(ConflatedBroadcastChannel.kt:255)
        at kotlinx.coroutines.channels.ConflatedBroadcastChannel.offer(ConflatedBroadcastChannel.kt:236)
        at androidx.paging.PageFetcherSnapshot.addHint(PageFetcherSnapshot.kt:189)
        at androidx.paging.PageFetcher$PagerUiReceiver.addHint(PageFetcher.kt:118)
        at androidx.paging.PagingDataDiffer$collectFrom$2$invokeSuspend$$inlined$collect$1$lambda$1.invokeSuspend(PagingDataDiffer.kt:93)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
        at kotlinx.coroutines.UndispatchedCoroutine.afterResume(Builders.common.kt:214)
        at kotlinx.coroutines.AbstractCoroutine.resumeWith(AbstractCoroutine.kt:113)
        at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:46)
        at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:56)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7523)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:941)

Issue 160192222

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