Unable to run parallel/sharded tests on Android

[simon-gilmurray]

Is there an existing issue for this?

• I have searched the existing issues and didn't find mine.

Steps to reproduce

It always fail except for on one device when running Android in parallel. Things I've tried:

• Creating devices from Maestro CLI and using them
• Using Android Studio created devices
• Calling a basic command maestro test --shards 3 maestro/
• Passing in explicit device names maestro --device 'emulator-5554,emulator-5556,emulator-5558' test -s 3 maestro/

Actual results

Only one device seems to run, 2/3 of the tests appear to fail straight away with 0s:

Logs:

[ERROR] m.cli.runner.TestSuiteInteractor - Failed to complete flow
io.grpc.StatusRuntimeException: UNAVAILABLE: io exception
    at io.grpc.stub.ClientCalls.toStatusRuntimeException(ClientCalls.java:271)
    at io.grpc.stub.ClientCalls.getUnchecked(ClientCalls.java:252)
    at io.grpc.stub.ClientCalls.blockingUnaryCall(ClientCalls.java:165)
    at maestro_android.MaestroDriverGrpc$MaestroDriverBlockingStub.deviceInfo(MaestroDriverGrpc.java:634)
...
Caused by: io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection refused: localhost/[0:0:0:0:0:0:0:1]:7006
Caused by: java.net.ConnectException: Connection refused

maestro.log

Expected results

Tests should run in parallel, as they do on iOS which is working fine

About app

React Native

About environment

macOS Sonoma 14.4.1 M2 Pro

Logs

Logs

[maestro.log](https://github.com/user-attachments/files/16430871/maestro.log)

Maestro version

1.37.4

How did you install Maestro?

install script (https://get.maestro.mobile.dev)

Anything else?

Slack thread:

https://mobile-dev-inc.slack.com/archives/C041FU72T54/p1722341761341199

[bartekpacia]

I did reproduce this problem. I started 2 emulators (API33 and API34), tests on one of them immediately failed, and the rest of flows (=the second half) ran normally on the second emulator.

Weird and definitely a bug.

[bartekpacia]

Should be mitigated by #1867, but the root cause (which is unknown at this moment) still persists.