Add Unit tests for Concurrency in ImageComposeScene

[jimgoog]

A couple of unit tests that we should probably add to our test suite to ensure we don't regress concurrency.

The unit tests are currently failing... possibly because of #1392
but I'm not positive because one of the stack traces I saw when running this lead me to believe that it might be unrelated. We might know more after #1392 is fixed, and either way, we should ensure these tests are also passing and don't regress.

@OptIn(ExperimentalTime::class, androidx.compose.ui.ExperimentalComposeUiApi::class)
fun main() {
    val service = Executors.newFixedThreadPool(50)

    for(i in 1..10000) {
        service.submit {
            val scene = ImageComposeScene(50, 50) {
                Box(Modifier.fillMaxSize().background(Color.White)) {
                    CircularProgressIndicator()
                }
            }
            scene.render() // start animation
            scene.render(milliseconds(50)).close()
            scene.close()
        }
    }

    service.shutdown()
}


@OptIn(ExperimentalTime::class, androidx.compose.ui.ExperimentalComposeUiApi::class)
fun main() {
    val scene = ImageComposeScene(50, 50) {
        Box(Modifier.fillMaxSize().background(Color.White)) {
            CircularProgressIndicator()
        }
    }
    scene.render() // start animation
    val service = Executors.newFixedThreadPool(8)
    (500 downTo 1 step 1).map { service.submit { scene.render(milliseconds(it)).close() } }.map { it.get() }
    service.shutdown()
    scene.close()
}

[igordmn]

After JetBrains/compose-multiplatform-core#199 the first test is still failing with:

java.util.concurrent.ExecutionException: java.lang.IllegalStateException: Reading a state that was created after the snapshot was taken or in a snapshot that has not yet been applied
	at java.base/java.util.concurrent.FutureTask.report(FutureTask.java:122)
	at java.base/java.util.concurrent.FutureTask.get(FutureTask.java:191)
	at androidx.compose.ui.ImageComposeSceneTest.multithreading 1(ImageComposeSceneTest.kt:148)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at androidx.compose.ui.test.junit4.ScreenshotTestRule$apply$1.evaluate(SkiaTest.desktop.kt:191)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.runTestClass(JUnitTestClassExecutor.java:110)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:58)
	at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecutor.execute(JUnitTestClassExecutor.java:38)
	at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:62)
	at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:51)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
	at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
	at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
	at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
	at com.sun.proxy.$Proxy2.processTestClass(Unknown Source)
	at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
	at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
	at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
	at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:133)
	at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:71)
	at worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
	at worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
Caused by: java.lang.IllegalStateException: Reading a state that was created after the snapshot was taken or in a snapshot that has not yet been applied
	at androidx.compose.runtime.snapshots.SnapshotKt.readError(Snapshot.kt:1527)
	at androidx.compose.runtime.snapshots.SnapshotKt.readable(Snapshot.kt:1522)
	at androidx.compose.runtime.snapshots.SnapshotKt.readable(Snapshot.kt:1513)
	at androidx.compose.runtime.SnapshotMutableStateImpl.getValue(SnapshotState.kt:130)
	at androidx.compose.material.Colors.getPrimary-0d7_KjU(Colors.kt:338)
	at androidx.compose.material.ProgressIndicatorKt.CircularProgressIndicator-aM-cp0Q(ProgressIndicator.kt:258)
	at androidx.compose.ui.ComposableSingletons$ImageComposeSceneTestKt$lambda-6$1.invoke(ImageComposeSceneTest.kt:140)
	at androidx.compose.ui.ComposableSingletons$ImageComposeSceneTestKt$lambda-6$1.invoke(ImageComposeSceneTest.kt:138)
	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:107)
	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:34)
	at androidx.compose.runtime.CompositionLocalKt.CompositionLocalProvider(CompositionLocal.kt:228)
	at androidx.compose.ui.ComposeScene$setContent$5.invoke(ComposeScene.skiko.kt:331)
	at androidx.compose.ui.ComposeScene$setContent$5.invoke(ComposeScene.skiko.kt:330)
	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:107)
	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:34)
	at androidx.compose.runtime.CompositionLocalKt.CompositionLocalProvider(CompositionLocal.kt:228)
	at androidx.compose.ui.platform.CompositionLocalsKt.ProvideCommonCompositionLocals(CompositionLocals.kt:166)
	at androidx.compose.ui.platform.Wrapper_skikoKt$setContent$2$1.invoke(Wrapper.skiko.kt:47)
	at androidx.compose.ui.platform.Wrapper_skikoKt$setContent$2$1.invoke(Wrapper.skiko.kt:46)
	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:107)
	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:34)
	at androidx.compose.ui.platform.Wrapper_skikoKt.provide(Wrapper.skiko.kt:65)
	at androidx.compose.ui.platform.Wrapper_skikoKt.access$provide(Wrapper.skiko.kt:1)
	at androidx.compose.ui.platform.Wrapper_skikoKt$setContent$2.invoke(Wrapper.skiko.kt:46)
	at androidx.compose.ui.platform.Wrapper_skikoKt$setContent$2.invoke(Wrapper.skiko.kt:45)
	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:107)
	at androidx.compose.runtime.internal.ComposableLambdaImpl.invoke(ComposableLambda.jvm.kt:34)
	at androidx.compose.runtime.ActualJvm_jvmKt.invokeComposable(ActualJvm.jvm.kt:72)
	at androidx.compose.runtime.ComposerImpl$doCompose$2$5.invoke(Composer.kt:2582)
	at androidx.compose.runtime.ComposerImpl$doCompose$2$5.invoke(Composer.kt:2571)
	at androidx.compose.runtime.SnapshotStateKt__DerivedStateKt.observeDerivedStateRecalculations(DerivedState.kt:247)
	at androidx.compose.runtime.SnapshotStateKt.observeDerivedStateRecalculations(Unknown Source)
	at androidx.compose.runtime.ComposerImpl.doCompose(Composer.kt:2571)
	at androidx.compose.runtime.ComposerImpl.composeContent$runtime(Composer.kt:2522)
	at androidx.compose.runtime.CompositionImpl.composeContent(Composition.kt:478)
	at androidx.compose.runtime.Recomposer.composeInitial$runtime(Recomposer.kt:748)
	at androidx.compose.runtime.CompositionImpl.setContent(Composition.kt:433)
	at androidx.compose.ui.platform.Wrapper_skikoKt.setContent(Wrapper.skiko.kt:45)
	at androidx.compose.ui.ComposeScene.setContent$ui(ComposeScene.skiko.kt:330)
	at androidx.compose.ui.ComposeScene.setContent$ui$default(ComposeScene.skiko.kt:309)
	at androidx.compose.ui.ComposeScene.setContent(ComposeScene.skiko.kt:291)
	at androidx.compose.ui.ImageComposeScene.<init>(ImageComposeScene.desktop.kt:118)
	at androidx.compose.ui.ImageComposeScene.<init>(ImageComposeScene.desktop.kt:104)
	at androidx.compose.ui.ImageComposeSceneTest.multithreading_1$lambda-7$lambda-6(ImageComposeSceneTest.kt:138)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.lang.Thread.run(Thread.java:829)

The second test isn't a valid test for the current implementation of ComposeScene. It doesn't support concurrent access from different threads. I have added info to the doc about that. Writing a test for not supporting multi-threading is probably impossible. Multi-threading is a hard thing to write and support for mutable entities, and in most cases isn't needed.

[ScottPierce]

I'm seeing this while running lots of tests in parallel as well.

We're using this for more than tests. We're using this for server side rendering of images, and because of this I'm scared to allow rendering of more than one image at a time.

[ScottPierce]

Using a mutex seems to work as a workaround for the time being:

private val IMAGE_COMPOSE_SCENE_MUTEX = Mutex()

suspend fun SafeImageComposeScene(
    width: Int,
    height: Int,
    density: Density = Density(1f),
    coroutineContext: CoroutineContext = Dispatchers.Unconfined,
    content: @Composable () -> Unit = {},
): ImageComposeScene {
    return IMAGE_COMPOSE_SCENE_MUTEX.withLock {
        ImageComposeScene(
            width = width,
            height = height,
            density = density,
            coroutineContext = coroutineContext,
            content = content
        )
    }
}

[m-sasha]

Reopened as

    val service = Executors.newFixedThreadPool(50)

    for(i in 1..10000) {
        service.submit {
            val scene = ImageComposeScene(50, 50) {
                Box(Modifier.fillMaxSize().background(Color.White)) {
                    CircularProgressIndicator()
                }
            }
            scene.render() // start animation
            scene.render(milliseconds(50)).close()
            scene.close()
        }
    }

    service.shutdown()

was succeeding just because ExecutorService.submit eats any exceptions thrown in the Runnable it's given. Running this:

        val exception: AtomicReference<Throwable?> = AtomicReference(null)
        val block = {
            try{
                val scene = ImageComposeScene(50, 50) {
                    Box(Modifier.fillMaxSize().background(Color.White)) {
                        CircularProgressIndicator()
                    }
                }
                scene.render() // start animation
                scene.render(50.milliseconds).close()
                scene.close()
            } catch (e: Throwable){
                exception.set(e)
            }
        }

        thread(block = block)
        thread(block = block)
        thread(block = block)

        Thread.sleep(1000)

        exception.get()?.printStackTrace()

will print

java.lang.IllegalStateException: Check failed.
	at androidx.compose.ui.Modifier$Node.attach$ui(Modifier.kt:200)
	at androidx.compose.ui.node.NodeChain.attach(NodeChain.kt:270)
	at androidx.compose.ui.node.LayoutNode.attach$ui(LayoutNode.kt:414)
	at androidx.compose.ui.platform.SkiaBasedOwner.<init>(SkiaBasedOwner.skiko.kt:191)
	at androidx.compose.ui.platform.SkiaBasedOwner.<init>(SkiaBasedOwner.skiko.kt:69)
	at androidx.compose.ui.ComposeScene.setContent$ui(ComposeScene.skiko.kt:366)
	at androidx.compose.ui.ComposeScene.setContent$ui$default(ComposeScene.skiko.kt:355)
	at androidx.compose.ui.ComposeScene.setContent(ComposeScene.skiko.kt:337)
	at androidx.compose.ui.ImageComposeScene.<init>(ImageComposeScene.skikoMain.kt:120)
	at androidx.compose.ui.ImageComposeScene.<init>(ImageComposeScene.skikoMain.kt:106)
	at androidx.compose.ui.ImageComposeSceneTest$run multiple ImageComposeScenes concurrently$block$1.invoke(ImageComposeSceneTest.kt:110)
	at androidx.compose.ui.ImageComposeSceneTest$run multiple ImageComposeScenes concurrently$block$1.invoke(ImageComposeSceneTest.kt:108)
	at kotlin.concurrent.ThreadsKt$thread$thread$1.run(Thread.kt:30)

[m-sasha]

The reason for the above failure is a race condition in NodeChain.padChain() and NodeChain.trimChain() due to SentinelHead.

[m-sasha]

Currently blocking concurrent use of ImageComposeScene:
https://issuetracker.google.com/issues/283162626
https://issuetracker.google.com/issues/283216580