gn recipe: Link GN with rpmalloc to speed it up.

NOTE: This is a reland of [1] with an updated rpmalloc
revision that includes fixes for the -Wconversion errors
that required reverting the original CL.

This CL changes the GN recipe to link the executable with the
rpmalloc allocator from

This speeds up the 'gn gen' operation of both Chromium and Fuchsia
operations by 28% and 12% respectively [1], and has slightly better
performance than using tcmalloc from gperftools in the Fuchsia case.

Note that:

- The sources are grabbed directly from, but it might be
  desirable to use a Chromium or Fuchsia supported mirror instead.

- Only Linux has been tested so far, so only this platform enables
  this build mode.

[1] Median measurements from 10 runs of 'gn gen' using the default
    Linux allocator (glibc), gperftools' tcmalloc, and rpmalloc:

      glibc (default):  9917 ms
      gperftools:       7858 ms  (26% faster)
      rpmalloc:         7752 ms  (28% faster)

      glibc (default):  4742 ms
      gperftools:       4186 ms  (13% faster)
      rpmalloc:         4235 ms  (12% faster)


Change-Id: I0860c34437faee7c1f97e01f831cbf25f49c819e
Commit-Queue: David Turner <>
Reviewed-by: Petr Hosek <>
10 files changed
tree: 30399c92573562854e0bdeef4638f813a9f6cbdc
  1. build/
  2. docs/
  3. examples/
  4. infra/
  5. misc/
  6. src/
  7. tools/
  8. .clang-format
  9. .editorconfig
  10. .gitignore
  11. .style.yapf
  14. OWNERS


GN is a meta-build system that generates build files for Ninja.

Related resources:

Getting a binary

You can download the latest version of GN binary for Linux, macOS and Windows.

Alternatively, you can build GN from source:

git clone
cd gn
python build/
ninja -C out
# To run tests:

On Windows, it is expected that cl.exe, link.exe, and lib.exe can be found in PATH, so you'll want to run from a Visual Studio command prompt, or similar.

On Linux and Mac, the default compiler is clang++, a recent version is expected to be found in PATH. This can be overridden by setting CC, CXX, and AR.


There is a simple example in examples/simple_build directory that is a good place to get started with the minimal configuration.

To build and run the simple example with the default gcc compiler:

cd examples/simple_build
../../out/gn gen -C out
ninja -C out

For a maximal configuration see the Chromium setup:

and the Fuchsia setup:

Reporting bugs

If you find a bug, you can see if it is known or report it in the bug database.

Sending patches

GN uses Gerrit for code review. The short version of how to patch is:

Register at

... edit code ...
ninja -C out && out/gn_unittests

Then, to upload a change for review:

git commit
git push origin HEAD:refs/for/master

The first time you do this you'll get an error from the server about a missing change-ID. Follow the directions in the error message to install the change-ID hook and run git commit --amend to apply the hook to the current commit.

When revising a change, use:

git commit --amend
git push origin HEAD:refs/for/master

which will add the new changes to the existing code review, rather than creating a new one.

We ask that all contributors sign Google's Contributor License Agreement (either individual or corporate as appropriate, select ‘any other Google project’).


You may ask questions and follow along with GN‘s development on Chromium’s gn-dev@ Google Group.