Flutter hangs in xcodebuild -showBuildSettings when building for iOS (v1.7.8+hotfix.3)

[orischwartz]

Building our Flutter app will hang about 20% of the time using the following command:

flutter build ios --release --no-codesign -t lib/main.dart

Android builds do not exhibit this behavior.

The last output we see is something like:

Warning: Building for device with codesigning disabled. You will have to manually codesign before deploying to device.
Building ws.flea.Fleaflicker for device (ios-release)...

Each build is executed from an identical clean environment.

Steps to Reproduce

Behavior is not reproducible every time. The current workaround is to retry the build (in a clean environment) which eventually succeeds.

Our build script is not much more complex than this (adapted from here):

git clone https://github.com/flutter/flutter.git
export PATH=`pwd`/flutter/bin:$PATH

flutter channel stable
flutter doctor

flutter build ios --release --no-codesign

I'd be happy to share the codebase and access to our continuous deployment tool (Microsoft AppCenter) with Flutter devs.

+ flutter doctor
Downloading Material fonts...                                       0.5s
Downloading android-arm-profile/darwin-x64 tools...                 0.3s
Downloading android-arm-release/darwin-x64 tools...                 0.2s
Downloading android-arm64-profile/darwin-x64 tools...               0.3s
Downloading android-arm64-release/darwin-x64 tools...               0.3s
Downloading android-x86 tools...                                    1.0s
Downloading android-x64 tools...                                    1.1s
Downloading android-arm tools...                                    0.5s
Downloading android-arm-profile tools...                            0.3s
Downloading android-arm-release tools...                            0.3s
Downloading android-arm64 tools...                                  0.5s
Downloading android-arm64-profile tools...                          0.4s
Downloading android-arm64-release tools...                          0.3s
Downloading ios tools...                                            2.5s
Downloading ios-profile tools...                                    1.5s
Downloading ios-release tools...                                    1.1s
Downloading Gradle Wrapper...                                       0.0s
Downloading package sky_engine...                                   0.1s
Downloading common tools...                                         0.5s
Downloading common tools...                                         0.5s
Downloading darwin-x64 tools...                                     1.6s
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, v1.7.8+hotfix.3, on Mac OS X 10.14.5 18F132, locale en)
[!] Android toolchain - develop for Android devices (Android SDK version 29.0.0)
    ! Some Android licenses not accepted.  To resolve this, run: flutter doctor --android-licenses
[✓] Xcode - develop for iOS and macOS (Xcode 10.2.1)
[✗] iOS tools - develop for iOS devices
    ✗ libimobiledevice and ideviceinstaller are not installed. To install with Brew, run:
        brew update
        brew install --HEAD usbmuxd
        brew link usbmuxd
        brew install --HEAD libimobiledevice
        brew install ideviceinstaller
    ✗ ios-deploy not installed. To install:
        brew install ios-deploy
[!] Android Studio (not installed)
[!] Connected device
    ! No devices available

! Doctor found issues in 4 categories.

We've observed this behavior since first using Flutter with v1.2.1. We only use the stable channel.

Dart package dependencies we've used since observing this behavior:

  shared_preferences
  protobuf
  http
  intl
  dynamic_theme
  timeago
  event_bus
  firebase_admob

(Possibly the same issue as described and closed in #28415. cc @eseidelGoogle)

[eseidelGoogle]

@kristiansagi may know if nevercode is seeing this too?

[eseidelGoogle]

@xster or @zanderso may have context. Thanks for the report!

[xster]

I'm not aware of any changes recently. Can you try

flutter build ios --release --no-codesign --verbose -t lib/main.dart and show us the output?

[orischwartz]

I am now unable to reproduce the issue with the verbose flag.

Going to close until I can gather more details.

[priitlatt]

@eseidelGoogle I can confirm on behalf of @NevercodeHQ / @kristiansagi that we've seen a spike in iOS builds getting stuck since July 9. flutter build ios ...args does not exit and the last bit of log is

Xcode build done.                                           123.4s

So far we've seen it happening on versions 1.7.8+hotfix.2, 1.7.8+hotfix.3, 1.8.0, 1.8.1-pre.2, 1.8.1-pre.22.

[eseidelGoogle]

Reopening based on @priitlatt's comments.

@jonahwilliams @zanderso does this show up in our analytics?

[orischwartz]

I will add a single data point from a build that got stuck with the verbose flag:

[   +1 ms] Copying service frameworks to '/Users/vsts/agent/2.154.1/work/1/s/ios/Frameworks'.
[   +1 ms] Creating service definitions manifest at '/Users/vsts/agent/2.154.1/work/1/s/ios/ServiceDefinitions.json'
[  +34 ms] Found plugin firebase_admob at /Users/vsts/.pub-cache/hosted/pub.dartlang.org/firebase_admob-0.9.0+1/
[        ] Found plugin firebase_analytics at /Users/vsts/.pub-cache/hosted/pub.dartlang.org/firebase_analytics-3.0.3/
[        ] Found plugin firebase_messaging at /Users/vsts/.pub-cache/hosted/pub.dartlang.org/firebase_messaging-5.1.0/
[   +1 ms] Found plugin flutter_image_compress at /Users/vsts/.pub-cache/hosted/pub.dartlang.org/flutter_image_compress-0.6.3/
[   +7 ms] Found plugin image_picker at /Users/vsts/.pub-cache/hosted/pub.dartlang.org/image_picker-0.6.0+15/
[   +5 ms] Found plugin package_info at /Users/vsts/.pub-cache/hosted/pub.dartlang.org/package_info-0.4.0+3/
[   +4 ms] Found plugin shared_preferences at /Users/vsts/.pub-cache/hosted/pub.dartlang.org/shared_preferences-0.4.3/
[   +6 ms] Found plugin url_launcher at /Users/vsts/.pub-cache/hosted/pub.dartlang.org/url_launcher-5.0.5/
[   +8 ms] executing: [/Users/vsts/agent/2.154.1/work/1/s/ios/Runner.xcodeproj/] /usr/bin/xcodebuild -project /Users/vsts/agent/2.154.1/work/1/s/ios/Runner.xcodeproj -target Runner -showBuildSettings

[Build got stuck here]

The next line should have been something like:

[+1449 ms] Exit code 0 from: /usr/bin/xcodebuild -project /Users/vsts/agent/2.154.1/work/1/s/ios/Runner.xcodeproj -target Runner -showBuildSettings

I will also add that we're seeing these less frequently than before the 1.7 stable release so I don't believe this is the same issue as #28415

[zanderso]

Looks like it's the invocation here that is hanging: https://github.com/flutter/flutter/blob/master/packages/flutter_tools/lib/src/macos/cocoapods.dart#L197. @stuartmorgan could you take a look?

[stuartmorgan-g]

I'm a bit confused; @orischwartz has log output that's stuck in a different place than @priitlatt. The bug was re-opened based on the former, but the last comment is focusing on the latter.

Do we have reason to believe the two cases are related even though the location where the build stopped is different?