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Confine context-specific state to the thread in UndispatchedCoroutine… #3155

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merged 3 commits into from Feb 1, 2022

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… in order to avoid state interference when the coroutine is updated concurrently.

Concurrency is inevitable in this scenario: when the coroutine that has UndispatchedCoroutine as its completion suspends, we have to clear the thread context, but while we are doing so, concurrent resume of the coroutine could've happened that also ends up in save/clear/update context

Fixes #2930

… in order to avoid state interference when the coroutine is updated concurrently.

Concurrency is inevitable in this scenario: when the coroutine that has UndispatchedCoroutine as its completion suspends, we have to clear the thread context, but while we are doing so, concurrent resume of the coroutine could've happened that also ends up in save/clear/update context

Fixes #2930
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@dkhalanskyjb dkhalanskyjb left a comment

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Can't several calls to thisCoroutine().clearThreadContext() happen in parallel?

kotlinx-coroutines-core/jvm/test/ThreadLocalStressTest.kt Outdated Show resolved Hide resolved
kotlinx-coroutines-core/jvm/test/ThreadLocalStressTest.kt Outdated Show resolved Hide resolved
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Now that I'm more awake I see that the question was wildly irrelevant.

qwwdfsad and others added 2 commits February 1, 2022 12:27
Co-authored-by: dkhalanskyjb <52952525+dkhalanskyjb@users.noreply.github.com>
Co-authored-by: dkhalanskyjb <52952525+dkhalanskyjb@users.noreply.github.com>
@qwwdfsad qwwdfsad merged commit 649d03e into develop Feb 1, 2022
@qwwdfsad qwwdfsad deleted the fix-tl-cleanup-race branch February 1, 2022 09:29
dee-tree pushed a commit to dee-tree/kotlinx.coroutines that referenced this pull request Jul 21, 2022
Kotlin#3155)

* Confine context-specific state to the thread in UndispatchedCoroutine in order to avoid state interference when the coroutine is updated concurrently.

Concurrency is inevitable in this scenario: when the coroutine that has UndispatchedCoroutine as its completion suspends, we have to clear the thread context, but while we are doing so, concurrent resume of the coroutine could've happened that also ends up in save/clear/update context

Fixes Kotlin#2930
pablobaxter pushed a commit to pablobaxter/kotlinx.coroutines that referenced this pull request Sep 14, 2022
Kotlin#3155)

* Confine context-specific state to the thread in UndispatchedCoroutine in order to avoid state interference when the coroutine is updated concurrently.

Concurrency is inevitable in this scenario: when the coroutine that has UndispatchedCoroutine as its completion suspends, we have to clear the thread context, but while we are doing so, concurrent resume of the coroutine could've happened that also ends up in save/clear/update context

Fixes Kotlin#2930
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2 participants