SIGSEGV on Android 7 #1683
Comments
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I boiled it further down by removing the dependency on coroutines-android and using the GlobalScope: class MainActivity : Activity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
GlobalScope.launch {
while (true) {
delay(100)
combine(flowOf(Unit), flowOf(Unit)) { _ -> Unit }.collect()
}
}
}
} |
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Most probably an R8 issue generating code that those device improperly handle as a few other cases. You should report to https://issuetracker.google.com/issues?q=componentid:326788%20status:open they are quite reactive and if the user base is high enough they might add a workaround. |
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Thanks for the detailed write-up! It could be because of the fact that for crossinlined coroutines (and flow has a lot of crossinline) pretty unusual bytecode (-> dex) shape is produced and some of the manufacturers could have missed it in their test suites. So as a (really limited) workaround, you can try to minimize the number of invoked |
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My current workaround is to create my own combine functions which are based on rxjava: /**
* Because of a bug in android 7 we can't use the regular combine functions and fallback to RxJava
* @see [https://github.com/Kotlin/kotlinx.coroutines/issues/1683]
*/
@PublishedApi
internal class Wrapper<T>(val value: T)
@PublishedApi
internal inline fun <T, R> combine(vararg sources: Flow<T>, crossinline transform: suspend (List<T>) -> R): Flow<R> {
val flowables = sources.map { it.map { value -> Wrapper(value) }.asFlowable() }
return Flowable
.combineLatest(flowables) {
@Suppress("UNCHECKED_CAST")
it.toList() as List<Wrapper<T>>
}
.asFlow()
.map { wrappedValues ->
val unwrapped = wrappedValues.map { it.value }
transform(unwrapped)
}
}
inline fun <T1, T2, R> combine(
flow: Flow<T1>,
flow2: Flow<T2>,
crossinline transform: suspend (T1, T2) -> R
): Flow<R> = combine(flow, flow2) { args ->
@Suppress("UNCHECKED_CAST")
transform(
args[0] as T1,
args[1] as T2
)
}
...With that in place all native crashes are gone. |
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Hi, we have exactly the same problem on a lot of Devices (processor Mediatek, Android 7) with a big combine function in our viewmodel ( 6 Flows combined (one combine with 4 Flows and one Flow which is a combine of 2 Flows) ). I can reproduce this bug on a Doogee Mix Lite. What is your advice please ? Use other operator ? Add a debounce, buffer ? I don't want to use Rx 😅 thanks |
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@PierreFourreau try to extract |
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Closing, please keep track on the https://issuetracker.google.com/issues/145569946 (thanks Paul for filing this!) |
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I have written a non-rx version: /**
* Because of a bug in android 7 we can't use the regular combine functions and have to use our own.
* @see [https://github.com/Kotlin/kotlinx.coroutines/issues/1683]
*/
@PublishedApi
internal object UnInitialized
@PublishedApi
internal inline fun <T, R> combine(vararg sources: Flow<T>, crossinline transform: suspend (List<T>) -> R): Flow<R> {
return channelFlow {
val values = Array<Any?>(sources.size) { UnInitialized }
coroutineScope {
sources.forEachIndexed { index, flow ->
launch {
flow.collect { value ->
values[index] = value
if (values.all { it !== UnInitialized }) {
@Suppress("UNCHECKED_CAST")
send(transform(values.toList() as List<T>))
}
}
}
}
}
}
} |
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Is your crash reproducible on every launch, or just the first one? We're facing a similar SIGSEG in libart.so, but on the first launch after update. Wondering if it's also got to do with R8. |
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On every launch. |
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@PaulWoitaschek in your minimized repro, I see that |
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I guess with my suggestion, the assumption is that your use case only requires combining two |
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@qwwdfsad, let's say I have a class that returns a class ObserveFoo(val dep1: Dep1, val dep2: Dep2, …, val depN: DepN) {
operator fun invoke(): Flow<Foo> {
return combine( // Real combine function from kotlinx.coroutines.flow.combine
dep1.observe(),
dep2.observe(),
…
depN.observe()
)
}
}Would this still run the risk of producing native crashes on some Android devices based on what we currently know? I am currently migrating some existing RxJava code over to Coroutines/Flow but I want to make sure I do not introduce native crashes as a result. Thank you! |
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@mhernand40 Unfortunately, we do not know. The stable reproducer is required in order to check such a hypothesis |
* Rework Flow.zip operator: improve its performance by 40%, collect one of the upstreams in the same coroutine as emitter
* Rework Flow.combine
* Get rid of two code paths
* Get rid of accidental O(N^2) where N is the number of flows that caused #2296
* Get rid of select that hits performance hard, improving performance by 50% in the pessimistic case
* Get rid of crossinlines in API and implementation to fix Android issues
* Make combine fairer and its results less surprising in sequential scenarios
* Improve stacktrace recovery and stackwalking for SafeCollector, flowOn and zip operators
* Update JMH
Fixes #1743
Fixes #1683
Fixes #2296
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The |
Issue
After updating my application I faced a lot of crashes on android 7 devices. I couldn't reproduce it on my nexus or on the emulator so I bought one of the crashing devices.
After spending half of the day I finally managed to find the root cause and I can reproduce it in a hello world project.
Sample
Crash
This leads to a sigsegv
I currently see about 1200 affected users..
Versions
Affected Devices
Note
Take a look at the last crash, maybe that's an indicator for what's going wrong. That one is no native crash but an android 7 only issue.
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