[GN] Configure a pool for copy_bundle_data and compile_xcassets tools.

build/toolchain/mac/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # TODO(brettw) Use "gcc_toolchain.gni" like the Linux toolchains. This requires
 # some enhancements since the commands on Mac are slightly different than on
 # Linux.
 
 import("../goma.gni")
 import("//build/config/ios/ios_sdk.gni")
 import("//build/config/mac/mac_sdk.gni")
 
 assert(host_os == "mac")
 
 import("//build/toolchain/goma.gni")
 import("//build/toolchain/toolchain.gni")
 
 if (use_goma) {
   goma_prefix = "$goma_dir/gomacc "
 } else {
   goma_prefix = ""
 }
 
+if (current_toolchain == default_toolchain) {
+  # Reduce the number of tasks using the copy_bundle_data and compile_xcassets
+  # tools as they can cause lots of I/O contention when invoking ninja with a
+  # large number of parallel jobs (e.g. when using distributed build like goma).
+  pool("bundle_pool") {
+    depth = 20

[Dirk Pranke, 2016/05/31 22:29:44]

Your desktop machine is probably a lot beefier than the bots, so this is
probably too high by default. It's probably better to re-use the
get_concurrent_links.py script to get default values (see, e.g.,
gcc_toolchain.gni).

You might also want this to be a declare_arg() so that we can tune this on bots
as needed.

... which made me just realize that the mac and ios toolchains aren't using
get_concurrent_links.py either, which is probably bad.

[sdefresne, 2016/06/01 08:22:29]

Done.

+  }
+}
+
 # This will copy the gyp-mac-tool to the build directory. We pass in the source
 # file of the mac tool.
 gyp_mac_tool_source =
     rebase_path("//tools/gyp/pylib/gyp/mac_tool.py", root_build_dir)
 exec_script("setup_toolchain.py", [ gyp_mac_tool_source ])
 
 # Shared toolchain definition. Invocations should set toolchain_os to set the
 # build args in this definition.
 template("mac_toolchain") {
   toolchain(target_name) {
@@ skipping 201 matching lines @@
     tool("copy") {
       command = copy_command
       description = copy_description
     }
 
     tool("copy_bundle_data") {
       _tool = rebase_path("//build/toolchain/mac/copy_bundle_data.py",
                           root_build_dir)
       command = "python $_tool {{source}} {{output}}"
       description = "COPY_BUNDLE_DATA {{source}} {{output}}"
+      pool = ":bundle_pool($default_toolchain)"
     }
     tool("compile_xcassets") {
       if (is_ios) {
         _configuration = "Release"
         if (is_debug) {
           _configuration = "Debug"
         }
 
         _compile_xcassets_env =
             "IPHONEOS_DEPLOYMENT_TARGET=$ios_deployment_target " +
             "CONFIGURATION=$ios_sdk_name-$_configuration " +
             "CONTENTS_FOLDER_PATH=\$(dirname {{output}})"
       } else {
         _compile_xcassets_env =
             "MACOSX_DEPLOYMENT_TARGET=$mac_deployment_target " +
             "UNLOCALIZED_RESOURCES_FOLDER_PATH=\$(dirname {{output}})"
       }
 
       command = "rm -f {{output}} && " +
                 "env $_compile_xcassets_env ./gyp-mac-tool compile-xcassets " +
                 "{} {{inputs}}"
       description = "COMPILE_XCASSETS {{output}}"
+      pool = ":bundle_pool($default_toolchain)"
     }
 
     toolchain_args() {
       current_cpu = invoker.toolchain_cpu
       current_os = invoker.toolchain_os
 
       # These values need to be passed through unchanged.
       host_toolchain = host_toolchain
       target_os = target_os
       target_cpu = target_cpu
@@ skipping 79 matching lines @@
 }
 
 mac_toolchain("x64") {
   toolchain_cpu = "x64"
   toolchain_os = "mac"
   cc = "${goma_prefix}/gcc"
   cxx = "${goma_prefix}/g++"
   ld = cxx
   is_clang = false
 }