Simplify GN pools, use in more places

Author: zanderso

DEPS

@@ -277,7 +277,7 @@ allowed_hosts = [
 ]
 
 deps = {
-  'src': 'https://github.com/flutter/buildroot.git' + '@' + '70a42312a688890eb1435a8c2760f6cbde324531',
+  'src': 'https://github.com/flutter/buildroot.git' + '@' + '7840a4af027fc21161d4ae14a3d4d9c9bab049a2',
 
   'src/flutter/third_party/depot_tools':
   Var('chromium_git') + '/chromium/tools/depot_tools.git' + '@' + '580b4ff3f5cd0dcaa2eacda28cefe0f45320e8f7',

build/dart/BUILD.gn

@@ -7,17 +7,6 @@ import("//flutter/common/config.gni")
 
 import("$dart_src/build/dart/copy_tree.gni")
 
-declare_args() {
-  # Maximum number of Dart processes to run in parallel.
-  #
-  # To avoid out-of-memory errors we explicitly reduce the number of jobs.
-  concurrent_dart_jobs = 1
-}
-
-pool("dart_pool") {
-  depth = concurrent_dart_jobs
-}
-
 if (build_engine_artifacts) {
   if (flutter_prebuilt_dart_sdk) {
     copy_trees("_copy_trees") {

build/dart/rules.gni

@@ -84,7 +84,7 @@ template("flutter_frontend_server") {
                              ],
                              [ "pool" ])
       deps = common_deps
-      pool = "//flutter/build/dart:dart_pool"
+      pool = "//build/toolchain:toolchain_pool"
       script = "//build/gn_run_binary.py"
       inputs = [ invoker.main_dart ]
       outputs = [ invoker.kernel_output ]
@@ -110,7 +110,7 @@ template("flutter_frontend_server") {
                              ],
                              [ "pool" ])
       deps = common_deps
-      pool = "//flutter/build/dart:dart_pool"
+      pool = "//build/toolchain:toolchain_pool"
       script = "$dart_src/pkg/frontend_server/bin/frontend_server_starter.dart"
       inputs = [ invoker.main_dart ]
       outputs = [ invoker.kernel_output ]
@@ -359,7 +359,7 @@ template("application_snapshot") {
       inputs = extra_inputs
       outputs = [ output ]
       depfile = depfile
-      pool = "//flutter/build/dart:dart_pool"
+      pool = "//build/toolchain:toolchain_pool"
 
       ext = ""
       if (is_win) {
@@ -380,7 +380,7 @@ template("application_snapshot") {
                                "visibility",
                              ])
       script = main_dart
-      pool = "//flutter/build/dart:dart_pool"
+      pool = "//build/toolchain:toolchain_pool"
       deps = extra_deps
       inputs = extra_inputs
       outputs = [ output ]

docs/rbe/rbe.md

@@ -151,14 +151,23 @@ RBE builds can be slow for a few different reasons. The most common reason is
 likely to be that the remote caches are cold. When the caches are warm, a
 compile step consists only of downloading the compiled TU from the cache. When
 the caches are cold, the remote workers must run the compilation commands,
-which takes more time.
+which takes more time. If the worker pool is overloaded, compile commands may
+run locally instead, which will also be slower.
 
 RBE builds can also be slow if your network connection is bandwidth constrained.
 Anecdotally, even with a warm cache, I have noticed slow builds from home due
 to RBE saturating my low-tier Comcast Business connection.
 
+For Googlers on a corp macOS device, both RBE and non-RBE builds can be slow
+due to various background and monitoring processes running. See
+[here](https://buganizer.corp.google.com/issues/324404733#comment16) for how
+to disable some of them. You should also disable Spotlight scanning of the
+engine source directory as described
+[here](go/building-chrome-mac#add-the-source-directory-to-the-spotlight-privacy-list).
+
 When RBE builds are slow, non-RBE builds may be faster, especially incremental
-builds.
+builds. You can disable remote builds without invalidating your existing build
+by setting the environment variable `RBE_exec_strategy=local`.
 
 ### Proxy status and debug logs
 

impeller/tools/BUILD.gn

@@ -339,6 +339,7 @@ template("impellerc") {
              ])
 
   _impellerc(target_name) {
+    pool = "//build/toolchain:toolchain_pool"
     shader_bundle = defined(invoker.shader_bundle)
 
     # When single_invocation is true, impellerc will be invoked exactly once. When it's

impeller/tools/impeller.gni

@@ -71,7 +71,7 @@ template("malioc_analyze_shaders") {
                                        ])
 
                 script = "//build/gn_run_malioc.py"
-                pool = "//flutter/impeller/tools:malioc_pool"
+                pool = "//build/toolchain:toolchain_pool"
 
                 # Nest all malioc output under its own subdirectory of root_gen_dir
                 # so that it's easier to diff it against the state before any changes.

impeller/tools/malioc.gni

@@ -232,7 +232,7 @@ compile_platform("strong_platform") {
     "$root_out_dir/flutter_patched_sdk/vm_outline_strong.dill",
   ]
 
-  pool = "//flutter/build/dart:dart_pool"
+  pool = "//build/toolchain:toolchain_pool"
 
   is_runtime_mode_release =
       flutter_runtime_mode == "release" || flutter_runtime_mode == "jit_release"

lib/snapshot/BUILD.gn

@@ -108,7 +108,7 @@ template("dart_snapshot_aot") {
 
     tool = "$dart_src/runtime/bin:gen_snapshot"
 
-    pool = "//flutter/build/dart:dart_pool"
+    pool = "//build/toolchain:toolchain_pool"
 
     inputs = [ invoker.dart_kernel ]
 

testing/testing.gni

@@ -532,7 +532,7 @@ def to_gn_args(args):
   else:
     gn_args['dart_runtime_mode'] = runtime_mode
 
-  gn_args['concurrent_dart_jobs'] = get_concurrent_jobs('1GB', '1GB')
+  gn_args['concurrent_toolchain_jobs'] = get_concurrent_jobs('1GB', '100MB')
 
   # Hardcoding this avoids invoking a relatively expensive python script from
   # GN, but removes the ability to use git-worktrees in the Dart checkout from
@@ -723,7 +723,6 @@ def to_gn_args(args):
     malioc_path = os.environ.get('MALIOC_PATH')
   if malioc_path:
     gn_args['impeller_malioc_path'] = malioc_path
-    gn_args['impeller_concurrent_malioc_jobs'] = get_concurrent_jobs('1GB', '100MB')
 
   if args.use_glfw_swiftshader:
     if get_host_os() == 'mac':