DataStore.stop or DataStore.clear may interrupt DataStore.start

[HuiSF]

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Language and Async Model

Java

Amplify Categories

DataStore

Gradle script dependencies

// Put output below this line
dependencies {
    implementation "com.amplifyframework:aws-datastore:1.32.2"
    implementation "com.amplifyframework:aws-api-appsync:1.32.2"
}

Environment information

------------------------------------------------------------
Gradle 6.7
------------------------------------------------------------

Build time:   2020-10-14 16:13:12 UTC
Revision:     312ba9e0f4f8a02d01854d1ed743b79ed996dfd3

Kotlin:       1.3.72
Groovy:       2.5.12
Ant:          Apache Ant(TM) version 1.10.8 compiled on May 10 2020
JVM:          1.8.0_292 (AdoptOpenJDK 25.292-b10)
OS:           Mac OS X 10.16 x86_64

Please include any relevant guides or documentation you're referencing

No response

Describe the bug

Original amplify-flutter issue: https://github.com/aws-amplify/amplify-flutter/issues/1479

Using the code example provided in this document.

    Amplify.DataStore.clear(
        {
            Amplify.DataStore.start(
                { Log.i("MyAmplifyApp", "DataStore started") },
                { Log.e("MyAmplifyApp", "Error starting DataStore", it) }
            )
        },
        { Log.e("MyAmplifyApp", "Error clearing DataStore", it) }
    )

the start process may be interrupted by the clear call due to below error

W/amplify:aws-api: Thread interrupted awaiting subscription acknowledgement.
    java.lang.InterruptedException
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedNanos(AbstractQueuedSynchronizer.java:1081)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireSharedNanos(AbstractQueuedSynchronizer.java:1369)
        at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:278)
        at com.amplifyframework.api.aws.SubscriptionEndpoint$Subscription.awaitSubscriptionReady(SubscriptionEndpoint.java:381)
        at com.amplifyframework.api.aws.SubscriptionEndpoint.requestSubscription(SubscriptionEndpoint.java:183)

It looks like that the onComplete action provided to the stop and the clear APIs is not guaranteed to be executed after stop and clear is completed finished.

Reproduction steps (if applicable)

1. using code example listed above
2. execute the logic
3. the start may fail (not 100% failing, but mostly)

Code Snippet

// Put your code below this line.

Log output

// Put your logs below this line

I/amplify:aws-datastore: Orchestrator lock acquired.
I/amplify:aws-datastore: Orchestrator transitioning from SYNC_VIA_API to STOPPED
I/amplify:aws-datastore: Setting currentState to LOCAL_ONLY
I/amplify:aws-datastore: Stopping subscription processor.
I/amplify:aws-datastore: Stopped subscription processor.
I/amplify:aws-datastore: Stopping observation of local storage changes.
I/amplify:aws-datastore: Setting currentState to STOPPED
I/amplify:flutter:datastore: Successfully stopped datastore remote synchronization
I/amplify:aws-datastore: Orchestrator lock released.
I/amplify:aws-datastore: Orchestrator lock acquired.
I/amplify:aws-datastore: Orchestrator transitioning from STOPPED to SYNC_VIA_API
I/amplify:aws-datastore: Starting to observe local storage changes.
D/EGL_emulation: app_time_stats: avg=8013.48ms min=8.68ms max=23772.65ms count=3
I/amplify:aws-datastore: Now observing local storage. Local changes will be enqueued to mutation outbox.
I/amplify:aws-datastore: Setting currentState to LOCAL_ONLY
I/amplify:aws-datastore: Setting currentState to SYNC_VIA_API
I/amplify:flutter:datastore: Successfully started datastore remote synchronization
I/amplify:aws-datastore: Starting API synchronization mode.
I/amplify:aws-datastore: Orchestrator lock released.
W/_triaging_marc: Long monitor contention with owner pool-4-thread-3 (19253) at void com.amplifyframework.api.aws.SubscriptionEndpoint.releaseSubscription(java.lang.String)(SubscriptionEndpoint.java:291) waiters=1 in void com.amplifyframework.api.aws.SubscriptionEndpoint.releaseSubscription(java.lang.String) for 377ms
I/flutter: outboxStatus
I/amplify:aws-datastore: Starting processing subscription events.
I/amplify:aws-api: No more active subscriptions. Closing web socket.
W/amplify:aws-api: Thread interrupted awaiting subscription acknowledgement.
    java.lang.InterruptedException
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedNanos(AbstractQueuedSynchronizer.java:1081)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireSharedNanos(AbstractQueuedSynchronizer.java:1369)
        at java.util.concurrent.CountDownLatch.await(CountDownLatch.java:278)
        at com.amplifyframework.api.aws.SubscriptionEndpoint$Subscription.awaitSubscriptionReady(SubscriptionEndpoint.java:381)
        at com.amplifyframework.api.aws.SubscriptionEndpoint.requestSubscription(SubscriptionEndpoint.java:183)
        at com.amplifyframework.api.aws.SubscriptionOperation.lambda$start$2$SubscriptionOperation(SubscriptionOperation.java:77)
        at com.amplifyframework.api.aws.-$$Lambda$SubscriptionOperation$dV6kPdbE8Z12Qd0_rE-16cujgUk.run(Unknown Source:2)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:463)
        at java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1137)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:637)
        at java.lang.Thread.run(Thread.java:1012)
W/_triaging_marc: Long monitor contention with owner pool-4-thread-2 (19252) at void com.amplifyframework.api.aws.SubscriptionEndpoint.releaseSubscription(java.lang.String)(SubscriptionEndpoint.java:291) waiters=2 in void com.amplifyframework.api.aws.SubscriptionEndpoint.requestSubscription(com.amplifyframework.api.graphql.GraphQLRequest, com.amplifyframework.api.aws.AuthorizationType, com.amplifyframework.core.Consumer, com.amplifyframework.core.Consumer, com.amplifyframework.core.Consumer, com.amplifyframework.core.Action) for 1.951s
Disconnected from the target VM, address: 'localhost:65258', transport: 'socket'

amplifyconfiguration.json

No response

GraphQL Schema

// Put your schema below this line

Additional information and screenshots

No response