from Jenkins log

Which Jenkins log? Please link. ;-)

This isn't (shouldn't be?) necessary and will instead result in different errors.

Rephrased: we already wait for device boot to complete:

    <Adb
        Condition=" '$(_ValidAdbTarget)' != 'True' "
        Arguments="$(_AdbTarget) wait-for-device"

adb wait-for-device is supposed to wait for the device to finish booting, before we send any other requests.

What is probably happening is yet another variation on #591: the emulator on the previous run never exited, so there's a "zombie" emulator running around. This can be verified by looking at the <CheckAdbTarget/> output of the Jenkins log: was there an already attached Android target?

If there was an already attached Android target -- as was the case in #591 -- then it's in a "zombie" state, which would explain why the adb uninstall is failing (with the same error, no less!). In which case adding:

adb shell 'while [ "`getprop sys.boot_completed`" != "1" ]; do echo Waiting for device to fully boot; sleep 1; done'

will turn a current failure scenario into a timeout scenario, as it takes 10 hours for a PR build to complete...

This would not be an improvement. ;-)

If instead there is not an attached Android target -- meaning #591 does not apply -- and there is no zombie emulator running around, then we have to start fearing that adb wait-for-device no longer works -- which is a horrifying thought -- and then come up with a workaround.

First, though, we need to determine whether we're dealing with a zombie emulator or not.

Unfortunately adb wait-for-device is not enough. It just waits until the device appears, but doesn't wait for boot to complete. I think it never worked differently. We already used sys.boot_completed property before, in monodroid emulator ruby script.

I think it is not zombie emulator case. Here's the part of the log.

        Using task CheckAdbTarget from Xamarin.Android.Tools.BootstrapTasks.CheckAdbTarget, Xamarin.Android.Tools.BootstrapTasks, Version=1.0.6

        Task CheckAdbTarget
          AdbTarget: 
          SdkVersion: 
        Tool /Users/builder/android-toolchain/sdk/platform-tools/adb execution started with arguments:  shell getprop ro.build.version.sdk 
        Environment variables being passed to the tool:
        error: no devices/emulators found
        Tool /Users/builder/android-toolchain/sdk/platform-tools/adb execution finished.
          [Output] AdbTarget: 
          [Output] IsValidTarget: False
Done executing task "CheckAdbTarget"

Here is the link to the latest Jenkins log https://jenkins.mono-project.com/view/Xamarin.Android/job/xamarin-android/417/consoleFull

It happens in every log I checked. The fix in this PR solves the issue. We have similar loop in monodroid ruby script.

I can add a counter so that we timeout, say after a minute or so. Sounds good?

I can add a counter so that we timeout, say after a minute or so. Sounds good?

Yes, that sounds wonderful. Please do so.