[tracing] Emit heap statistics at every GC.

When the 'disabled-by-default-v8.gc' category is enabled, emit an instant event
with heap statistics after every GC. The data that's emitted is the same as what
the V8 API gives you with `GetHeapStatistics()` and `GetHeapSpaceStatistics()`.

We generate JSON with the following format:

```
{
 "isolate": "0x55dd5cf03b50",
 "id": 1,
 "time_ms": 42.619,

 "total_heap_size": 3981312,
 "total_heap_size_executable": 573440,
 "total_physical_size": 2820440,
 "total_available_size": 2195254440,

 "used_heap_size": 1799616,
 "heap_size_limit": 2197815296,
 "malloced_memory": 251024,
 "external_memory": 2981,
 "peak_malloced_memory": 589280,

 "spaces": [
   {
     "name": "read_only_space",
     "size": 262144,
     "used_size": 32568,
     "available_size": 229256,
     "physical_size": 32888
   },
   {
     "name": "new_space",
     "size": 2097152,
     "used_size": 903392,
     "available_size": 143904,
     "physical_size": 1856136
   },
   ...
 ]
}
```

Bug: v8:9186
Change-Id: I0d07aa37b65d45778d6b47dbe6e07a9dd25d1097
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1619763
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Pierre Langlois <pierre.langlois@arm.com>
Cr-Commit-Position: refs/heads/master@{#61667}
6 files changed
tree: cebf4342b1715a3d095b142d3a23f8049158b524
  1. .clang-format
  2. .clang-tidy
  3. .editorconfig
  4. .git-blame-ignore-revs
  5. .gitattributes
  6. .gitignore
  7. .gn
  8. .vpython
  9. .ycm_extra_conf.py
  10. AUTHORS
  11. BUILD.gn
  12. CODE_OF_CONDUCT.md
  13. COMMON_OWNERS
  14. ChangeLog
  15. DEPS
  16. ENG_REVIEW_OWNERS
  17. INFRA_OWNERS
  18. LICENSE
  19. LICENSE.fdlibm
  20. LICENSE.strongtalk
  21. LICENSE.v8
  22. LICENSE.valgrind
  23. OWNERS
  24. PRESUBMIT.py
  25. README.md
  26. WATCHLISTS
  27. benchmarks/
  28. build_overrides/
  29. codereview.settings
  30. custom_deps/
  31. docs/
  32. gni/
  33. include/
  34. infra/
  35. samples/
  36. snapshot_toolchain.gni
  37. src/
  38. test/
  39. testing/
  40. third_party/
  41. tools/
README.md

V8 JavaScript Engine

V8 is Google's open source JavaScript engine.

V8 implements ECMAScript as specified in ECMA-262.

V8 is written in C++ and is used in Google Chrome, the open source browser from Google.

V8 can run standalone, or can be embedded into any C++ application.

V8 Project page: https://v8.dev/docs

Getting the Code

Checkout depot tools, and run

    fetch v8

This will checkout V8 into the directory v8 and fetch all of its dependencies. To stay up to date, run

    git pull origin
    gclient sync

For fetching all branches, add the following into your remote configuration in .git/config:

    fetch = +refs/branch-heads/*:refs/remotes/branch-heads/*
    fetch = +refs/tags/*:refs/tags/*

Contributing

Please follow the instructions mentioned at v8.dev/docs/contribute.