[vm] Make vm/dart/isolates/reload_many_isolates_live_and_die_test more robust

This test is launcing a subprocess with N parallel tracks.
Each track is effectively a child isolate that will make a
tail call to another child isolate. This process will continue
until a reload is requested.

=> So it tests performing hot-reload of an application that has
a lot of isolate creation, initialization, destructions in it.

Right now it uses N=20 for normal architectures (and N=2 for
simulators).

It turns out that part of the slowness of this test is due to the
subprocess's "vm-service" sending massive amounts of data via the
websocket to the parent process that performs reloading:

Each isolate will produce 4 events:
  * IsolateStart
  * IsolateRunnable
  * ServiceExtensionAdded
  * IsolateExit
and send those to the `vm-service` isolate. The service isolate will
then send those further via the WebSocket API to the parent process.

=> For 400k isolates this may send 3 GB of data via websocket.
=> The individual events most likely result in individual syscalls.
=> Networking stack on windows/mac may not be soo good, which
would explain why it's more likely to time out there vs linux

We ensure the helper reload utilites unsubscribe to the "isolate"
stream once there's no longer a need for it.
=> This will avoid the 3 GB of network traffic.
=> It will avoid a subset (but not all) of the isolate -> vm-service events

Issue https://github.com/dart-lang/sdk/issues/51347
TEST=vm/dart{,_2}/isolates/reload_many_isolates_live_and_die_test

Change-Id: I971b983a08ea8febd38e8b40a53ed6b114c4daca
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/306421
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
5 files changed
tree: 37e44e646a27db11ad3557c7ce41fadd74ebc0c5
  1. .dart_tool/
  2. .github/
  3. benchmarks/
  4. build/
  5. docs/
  6. pkg/
  7. runtime/
  8. samples/
  9. sdk/
  10. tests/
  11. third_party/
  12. tools/
  13. utils/
  14. .clang-format
  15. .gitattributes
  16. .gitconfig
  17. .gitignore
  18. .gn
  19. .mailmap
  20. .style.yapf
  21. .vpython
  22. AUTHORS
  23. BUILD.gn
  24. CHANGELOG.md
  25. codereview.settings
  26. CONTRIBUTING.md
  27. DEPS
  28. LICENSE
  29. OWNERS
  30. PATENT_GRANT
  31. PRESUBMIT.py
  32. README.dart-sdk
  33. README.md
  34. sdk.code-workspace
  35. sdk_args.gni
  36. SECURITY.md
  37. WATCHLISTS
README.md

Dart

A client-optimized language for fast apps on any platform

Dart is:

  • Optimized for UI: Develop with a programming language specialized around the needs of user interface creation.

  • Productive: Make changes iteratively: use hot reload to see the result instantly in your running app.

  • Fast on all platforms: Compile to ARM & x64 machine code for mobile, desktop, and backend. Or compile to JavaScript for the web.

Dart's flexible compiler technology lets you run Dart code in different ways, depending on your target platform and goals:

  • Dart Native: For programs targeting devices (mobile, desktop, server, and more), Dart Native includes both a Dart VM with JIT (just-in-time) compilation and an AOT (ahead-of-time) compiler for producing machine code.

  • Dart Web: For programs targeting the web, Dart Web includes both a development time compiler (dartdevc) and a production time compiler (dart2js).

Dart platforms illustration

License & patents

Dart is free and open source.

See LICENSE and PATENT_GRANT.

Using Dart

Visit dart.dev to learn more about the language, tools, and to find codelabs.

Browse pub.dev for more packages and libraries contributed by the community and the Dart team.

Our API reference documentation is published at api.dart.dev, based on the stable release. (We also publish docs from our beta and dev channels, as well as from the primary development branch).

Building Dart

If you want to build Dart yourself, here is a guide to getting the source, preparing your machine to build the SDK, and building.

There are more documents on our wiki.

Contributing to Dart

The easiest way to contribute to Dart is to file issues.

You can also contribute patches, as described in Contributing.