kotlinx-coroutines-core/jvm/src/CoroutineContext.kt [223:264]:
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    @Volatile
    private var threadLocalIsSet = false

    init {
        /*
         * This is a hack for a very specific case in #2930 unless #3253 is implemented.
         * 'ThreadLocalStressTest' covers this change properly.
         *
         * The scenario this change covers is the following:
         * 1) The coroutine is being started as plain non kotlinx.coroutines related suspend function,
         *    e.g. `suspend fun main` or, more importantly, Ktor `SuspendFunGun`, that is invoking
         *    `withContext(tlElement)` which creates `UndispatchedCoroutine`.
         * 2) It (original continuation) is then not wrapped into `DispatchedContinuation` via `intercept()`
         *    and goes neither through `DC.run` nor through `resumeUndispatchedWith` that both
         *    do thread context element tracking.
         * 3) So thread locals never got chance to get properly set up via `saveThreadContext`,
         *    but when `withContext` finishes, it attempts to recover thread locals in its `afterResume`.
         *
         * Here we detect precisely this situation and properly setup context to recover later.
         *
         */
        if (uCont.context[ContinuationInterceptor] !is CoroutineDispatcher) {
            /*
             * We cannot just "read" the elements as there is no such API,
             * so we update-restore it immediately and use the intermediate value
             * as the initial state, leveraging the fact that thread context element
             * is idempotent and such situations are increasingly rare.
             */
            val values = updateThreadContext(context, null)
            restoreThreadContext(context, values)
            saveThreadContext(context, values)
        }
    }

    fun saveThreadContext(context: CoroutineContext, oldValue: Any?) {
        threadLocalIsSet = true // Specify that thread-local is touched at all
        threadStateToRecover.set(context to oldValue)
    }

    fun clearThreadContext(): Boolean {
        return !(threadLocalIsSet && threadStateToRecover.get() == null).also {
            threadStateToRecover.remove()
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kotlinx-coroutines-core/native/src/CoroutineContext.kt [159:200]:
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    @Volatile
    private var threadLocalIsSet = false

    init {
        /*
         * This is a hack for a very specific case in #2930 unless #3253 is implemented.
         * 'ThreadLocalStressTest' covers this change properly.
         *
         * The scenario this change covers is the following:
         * 1) The coroutine is being started as plain non kotlinx.coroutines related suspend function,
         *    e.g. `suspend fun main` or, more importantly, Ktor `SuspendFunGun`, that is invoking
         *    `withContext(tlElement)` which creates `UndispatchedCoroutine`.
         * 2) It (original continuation) is then not wrapped into `DispatchedContinuation` via `intercept()`
         *    and goes neither through `DC.run` nor through `resumeUndispatchedWith` that both
         *    do thread context element tracking.
         * 3) So thread locals never got chance to get properly set up via `saveThreadContext`,
         *    but when `withContext` finishes, it attempts to recover thread locals in its `afterResume`.
         *
         * Here we detect precisely this situation and properly setup context to recover later.
         *
         */
        if (uCont.context[ContinuationInterceptor] !is CoroutineDispatcher) {
            /*
             * We cannot just "read" the elements as there is no such API,
             * so we update-restore it immediately and use the intermediate value
             * as the initial state, leveraging the fact that thread context element
             * is idempotent and such situations are increasingly rare.
             */
            val values = updateThreadContext(context, null)
            restoreThreadContext(context, values)
            saveThreadContext(context, values)
        }
    }

    fun saveThreadContext(context: CoroutineContext, oldValue: Any?) {
        threadLocalIsSet = true // Specify that thread-local is touched at all
        threadStateToRecover.set(context to oldValue)
    }

    fun clearThreadContext(): Boolean {
        return !(threadLocalIsSet && threadStateToRecover.get() == null).also {
            threadStateToRecover.remove()
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