Ruby artifact speedup (grpc#28542)

* fix ruby native extension build parallelism defaults

* allow overriding ruby artifact build parallelism with GRPC_RUBY_BUILD_PROCS

* honor --inner_jobs for ruby artifact build

* always start building ruby artifacts first

* fine tune grpc_distribtests_ruby.sh

* address review feedback

* strip newline from nproc output

Rakefile

@@ -82,6 +82,8 @@ desc 'Build the Windows gRPC DLLs for Ruby'
 task 'dlls' do
   grpc_config = ENV['GRPC_CONFIG'] || 'opt'
   verbose = ENV['V'] || '0'
+  # use env variable to set artifact build paralellism
+  nproc_override = ENV['GRPC_RUBY_BUILD_PROCS'] || `nproc`.strip
 
   env = 'CPPFLAGS="-D_WIN32_WINNT=0x600 -DNTDDI_VERSION=0x06000000 -DUNICODE -D_UNICODE -Wno-unused-variable -Wno-unused-result -DCARES_STATICLIB -Wno-error=conversion -Wno-sign-compare -Wno-parentheses -Wno-format -DWIN32_LEAN_AND_MEAN" '
   env += 'CFLAGS="-Wno-incompatible-pointer-types" '
@@ -93,6 +95,8 @@ task 'dlls' do
   env += 'EMBED_CARES=true '
   env += 'BUILDDIR=/tmp '
   env += "V=#{verbose} "
+  env += "GRPC_RUBY_BUILD_PROCS=#{nproc_override} "
+
   out = GrpcBuildConfig::CORE_WINDOWS_DLL
 
   w64 = { cross: 'x86_64-w64-mingw32', out: 'grpc_c.64.ruby', platform: 'x64-mingw32' }
@@ -105,7 +109,7 @@ task 'dlls' do
     env_comp += "LDXX=#{opt[:cross]}-g++ "
     run_rake_compiler(opt[:platform], <<~EOT)
       gem update --system --no-document && \
-      #{env} #{env_comp} make -j`nproc` #{out} && \
+      #{env} #{env_comp} make -j#{nproc_override} #{out} && \
       #{opt[:cross]}-strip -x -S #{out} && \
       cp #{out} #{opt[:out]}
     EOT
@@ -129,6 +133,9 @@ task 'gem:native' do
     end
     system "bundle exec rake cross native gem RUBY_CC_VERSION=#{ruby_cc_versions} V=#{verbose} GRPC_CONFIG=#{grpc_config}"
   else
+    # use env variable to set artifact build paralellism
+    nproc_override = ENV['GRPC_RUBY_BUILD_PROCS'] || `nproc`.strip
+
     Rake::Task['dlls'].execute
     ['x86-mingw32', 'x64-mingw32'].each do |plat|
       run_rake_compiler(plat, <<~EOT)
@@ -138,7 +145,8 @@ task 'gem:native' do
         bundle exec rake native:#{plat} pkg/#{spec.full_name}-#{plat}.gem pkg/#{spec.full_name}.gem \
           RUBY_CC_VERSION=#{ruby_cc_versions} \
           V=#{verbose} \
-          GRPC_CONFIG=#{grpc_config}
+          GRPC_CONFIG=#{grpc_config} \
+          GRPC_RUBY_BUILD_PROCS=#{nproc_override}
       EOT
     end
     # Truncate grpc_c.*.ruby files because they're for Windows only.
@@ -152,7 +160,8 @@ task 'gem:native' do
         bundle exec rake native:#{plat} pkg/#{spec.full_name}-#{plat}.gem pkg/#{spec.full_name}.gem \
           RUBY_CC_VERSION=#{ruby_cc_versions} \
           V=#{verbose} \
-          GRPC_CONFIG=#{grpc_config}
+          GRPC_CONFIG=#{grpc_config} \
+          GRPC_RUBY_BUILD_PROCS=#{nproc_override}
       EOT
     end
   end

src/ruby/ext/grpc/extconf.rb

@@ -69,7 +69,7 @@
 unless windows
   puts 'Building internal gRPC into ' + grpc_lib_dir
   nproc = 4
-  nproc = Etc.nprocessors * 2 if Etc.respond_to? :nprocessors
+  nproc = Etc.nprocessors if Etc.respond_to? :nprocessors
   nproc_override = ENV['GRPC_RUBY_BUILD_PROCS']
   unless nproc_override.nil? or nproc_override.size == 0
     nproc = nproc_override

templates/src/ruby/ext/grpc/extconf.rb.template

@@ -71,7 +71,7 @@
   unless windows
     puts 'Building internal gRPC into ' + grpc_lib_dir
     nproc = 4
-    nproc = Etc.nprocessors * 2 if Etc.respond_to? :nprocessors
+    nproc = Etc.nprocessors if Etc.respond_to? :nprocessors
     nproc_override = ENV['GRPC_RUBY_BUILD_PROCS']
     unless nproc_override.nil? or nproc_override.size == 0
       nproc = nproc_override

tools/internal_ci/linux/grpc_distribtests_ruby.sh

@@ -31,7 +31,7 @@ rvm --default use ruby-2.5.7
 set -ex
 
 # Build all ruby linux artifacts (this step actually builds all the binary wheels and source archives)
-tools/run_tests/task_runner.py -f artifact linux ruby ${TASK_RUNNER_EXTRA_FILTERS} -j 6 -x build_artifacts/sponge_log.xml || FAILED="true"
+tools/run_tests/task_runner.py -f artifact linux ruby ${TASK_RUNNER_EXTRA_FILTERS} -j 2 --inner_jobs 16 -x build_artifacts/sponge_log.xml || FAILED="true"
 
 # Ruby "build_package" step is basically just a passthough for the "grpc" gems, so it's enough to just
 # copy the native gems directly to the "distribtests" step and skip the "build_package" phase entirely.

tools/run_tests/artifacts/artifact_targets.py

@@ -210,14 +210,17 @@ def pre_build_jobspecs(self):
         return []
 
     def build_jobspec(self, inner_jobs=None):
-        # TODO(jtattermusch): honor inner_jobs arg for this task.
-        del inner_jobs
+        environ = {}
+        if inner_jobs is not None:
+            # set number of parallel jobs when building native extension
+            environ['GRPC_RUBY_BUILD_PROCS'] = str(inner_jobs)
         # Ruby build uses docker internally and docker cannot be nested.
         # We are using a custom workspace instead.
         return create_jobspec(
             self.name, ['tools/run_tests/artifacts/build_artifact_ruby.sh'],
             use_workspace=True,
-            timeout_seconds=90 * 60)
+            timeout_seconds=90 * 60,
+            environ=environ)
 
 
 class CSharpExtArtifact:
@@ -376,9 +379,19 @@ def __str__(self):
         return self.name
 
 
+def _reorder_targets_for_build_speed(targets):
+    """Reorder targets to achieve optimal build speed"""
+    # ruby artifact build builds multiple artifacts at once, so make sure
+    # we start building ruby artifacts first, so that they don't end up
+    # being a long tail once everything else finishes.
+    return list(
+        sorted(targets,
+               key=lambda target: 0 if target.name.startswith('ruby_') else 1))
+
+
 def targets():
     """Gets list of supported targets"""
-    return [
+    return _reorder_targets_for_build_speed([
         ProtocArtifact('linux', 'x64', presubmit=True),
         ProtocArtifact('linux', 'x86', presubmit=True),
         ProtocArtifact('linux', 'aarch64', presubmit=True),
@@ -448,4 +461,4 @@ def targets():
         RubyArtifact('macos', 'x64', presubmit=True),
         PHPArtifact('linux', 'x64', presubmit=True),
         PHPArtifact('macos', 'x64', presubmit=True)
-    ]
+    ])