Set GOMAXPROCS=runtime.NumCPU().

client/cmd/isolated/common.go

 // Copyright 2015 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.
 
 package main
 
 import (
+        "runtime"
+
         "github.com/luci/luci-go/client/internal/common"
         "github.com/luci/luci-go/client/isolatedclient"
         "github.com/maruel/subcommands"
 )
 
+func init() {
+        runtime.GOMAXPROCS(runtime.NumCPU())
+}
+
 type commonFlags struct {
         subcommands.CommandRunBase
         defaultFlags  common.Flags
         isolatedFlags isolatedclient.Flags
 }
 
 func (c *commonFlags) Init() {
         c.defaultFlags.Init(&c.Flags)
         c.isolatedFlags.Init(&c.Flags)
 }
 
 func (c *commonFlags) Parse() error {
         if err := c.defaultFlags.Parse(); err != nil {
                 return err
         }
         return c.isolatedFlags.Parse()
 }
 
 func (c *commonFlags) Close() error {
         err := c.defaultFlags.Close()
         if err2 := c.isolatedFlags.Close(); err == nil {
                 err = err2
         }
         return err
 }