Occasional death-by-signal of tool processes only seen since #1851

[jcollins-g]

Rarely, a tool will die with SIGBUS/SIGABRT generating flutter docs. Need to investigate.

[jcollins-g]

An example of a segfaulting tool execution.

flutter-docs: error: tool execution failed: Tool "sample" returned non-zero exit code (-6) when run as "/tmp/flutterQLZKVO/bin/cache/dart-sdk/bin/dart /tmp/dartdoc_snapshot_cache_YCKUHF/snapshot_0 --type=sample" from Directory: '/tmp/flutterQLZKVO/dev/docs'
flutter-docs: Input to sample was:
flutter-docs:
flutter-docs: dart flutter-docs: /// A copper coffee pot, as desired by Ben Turpin. flutter-docs: /// ...documentation... flutter-docs: @Category(<String>['Pots', 'Coffee']) flutter-docs: @Category(<String>['Copper', 'Cookware']) flutter-docs: @DocumentationIcon('https://example.com/images/coffee.png') flutter-docs: @Summary('A proper cup of coffee is made in a proper copper coffee pot.') flutter-docs: class CopperCoffeePot { flutter-docs: // ...code... flutter-docs: } flutter-docs:
flutter-docs: Stderr output was:
flutter-docs:
flutter-docs: ===== CRASH =====
flutter-docs: version=2.1.0-dev.9.4.flutter-f9ebf21297 (Thu Nov 8 23:00:07 2018 +0100) on "linux_x64"
flutter-docs: si_signo=Segmentation fault(11), si_code=128, si_addr=(nil)
flutter-docs: Dumping native stack trace for thread 1658
flutter-docs: Stack dump aborted because InitialRegisterCheck failed.
flutter-docs:
flutter-docs: , from foundation.Category: (file:///tmp/flutterQLZKVO/packages/flutter/lib/src/foundation/annotations.dart:40:7)

[jcollins-g]

It looks like despite some precautions taken (the snapshot condition variable) to avoid this, we are somehow launching multiple snapshot generations in parallel. While I can't say for sure this is the cause of the crashes, it's definitely not a good thing.

flutter-docs: parsing /tmp/pubcacheZAKPSY/hosted/pub.dartlang.org/process-3.0.9/lib/src/record_replay/common.dart...
flutter-docs: parsing /tmp/pubcacheZAKPSY/hosted/pub.dartlang.org/process-3.0.9/lib/src/record_replay/constants.dart...
flutter-docs: Tool "sample" starting (#0), run as: /tmp/flutterHPYPAK/bin/cache/dart-sdk/bin/dart --snapshot=/tmp/dartdoc_snapshot_cache_OEIOAB/snapshot_0 --snapshot_kind=app-jit /tmp/flutterHPYPAK/dev/snippets/lib/main.dart --type=sample
flutter-docs: from: Directory: '/tmp/flutterHPYPAK/dev/docs'
flutter-docs: Tool "sample" starting (#1), run as: /tmp/flutterHPYPAK/bin/cache/dart-sdk/bin/dart --snapshot=/tmp/dartdoc_snapshot_cache_OEIOAB/snapshot_0 --snapshot_kind=app-jit /tmp/flutterHPYPAK/dev/snippets/lib/main.dart --type=sample
flutter-docs: from: Directory: '/tmp/flutterHPYPAK/dev/docs'
flutter-docs: Tool "sample" starting (#2), run as: /tmp/flutterHPYPAK/bin/cache/dart-sdk/bin/dart --snapshot=/tmp/dartdoc_snapshot_cache_OEIOAB/snapshot_0 --snapshot_kind=app-jit /tmp/flutterHPYPAK/dev/snippets/lib/main.dart --type=sample
flutter-docs: from: Directory: '/tmp/flutterHPYPAK/dev/docs'
flutter-docs: Tool "sample" (#1 complete, run as /tmp/flutterHPYPAK/bin/cache/dart-sdk/bin/dart --snapshot=/tmp/dartdoc_snapshot_cache_OEIOAB/snapshot_0 --snapshot_kind=app-jit /tmp/flutterHPYPAK/dev/snippets/lib/main.dart --type=sample
flutter-docs: Tool "sample" (#0 complete, run as /tmp/flutterHPYPAK/bin/cache/dart-sdk/bin/dart --snapshot=/tmp/dartdoc_snapshot_cache_OEIOAB/snapshot_0 --snapshot_kind=app-jit /tmp/flutterHPYPAK/dev/snippets/lib/main.dart --type=sample
flutter-docs: Tool "sample" (#2 complete, run as /tmp/flutterHPYPAK/bin/cache/dart-sdk/bin/dart --snapshot=/tmp/dartdoc_snapshot_cache_OEIOAB/snapshot_0 --snapshot_kind=app-jit /tmp/flutterHPYPAK/dev/snippets/lib/main.dart --type=sample
flutter-docs: Tool "sample" starting (#3), run as: /tmp/flutterHPYPAK/bin/cache/dart-sdk/bin/dart /tmp/dartdoc_snapshot_cache_OEIOAB/snapshot_0 --type=sample
flutter-docs: from: Directory: '/tmp/flutterHPYPAK/dev/docs'

[jcollins-g]

#1862 so far looks like it makes this go away -- verified that it eliminates the multiple-snapshotting problem and I've seen no more crashes on travis since doing that.