Add counting the number of CPU's in goma module

scripts/slave/recipe_modules/goma/api.py

Index: scripts/slave/recipe_modules/goma/api.py
diff --git a/scripts/slave/recipe_modules/goma/api.py b/scripts/slave/recipe_modules/goma/api.py
index a2d939a2caf44a47c23cb1952d5b0693e48bfbee..9518f9a40ad499b40f5bd5ee8e324c1b3a17958f 100644
--- a/scripts/slave/recipe_modules/goma/api.py
+++ b/scripts/slave/recipe_modules/goma/api.py
@@ -14,6 +14,7 @@ class GomaApi(recipe_api.RecipeApi):
 
     self._goma_ctl_env = {}
     self._cloudtail_pid = None
+    self._goma_jobs = 50

[ukai, 2016/09/02 05:02:14]

can recipe_module user configure specific number for goma_jobs?

[tikuta, 2016/09/05 03:07:27]

User can set jobs by themselves where they run build.
I propose goma_jobs as recommended the number of jobs.

 
   @property
   def service_account_json_path(self):
@@ -31,6 +32,10 @@ class GomaApi(recipe_api.RecipeApi):
     assert self._goma_dir
     return self.m.path.join(self._goma_dir, 'jsonstatus')
 
+  @property
+  def goma_jobs(self):
+    return self._goma_jobs
+
   def ensure_goma(self, canary=False):
     with self.m.step.nest('ensure_goma'):
       with self.m.step.context({'infra_step': True}):
@@ -65,6 +70,18 @@ class GomaApi(recipe_api.RecipeApi):
                              {goma_package: ref,
                               cloudtail_package: cloudtail_version})
 
+          step_result = self.m.python.inline(
+            'get the number of cpus',
+            """
+            import multiprocessing
+            print min(200, multiprocessing.cpu_count() * 10)

[shinyak, 2016/09/01 09:38:28]

I didn't set 200 for all platforms? Only Mac & Windows.
Not sure backend resource is enough. (See compile.py comment)

[ukai, 2016/09/02 05:02:14]

https://docs.python.org/2.7/library/multiprocessing.html#multiprocessing.cpu_...

may raise NotImplementedError?

[tikuta, 2016/09/05 03:01:37]

Done.

[tikuta, 2016/09/05 03:01:37]

For linux, I set 80 for the number of jobs.

+            """,
+            stdout=self.m.raw_io.output(),
+            step_test_data=(
+                lambda: self.m.raw_io.test_api.stream_output('40'))
+          )
+          self._goma_jobs = int(step_result.stdout)
+
           return self._goma_dir
         except self.m.step.StepFailure:
           # TODO(phajdan.jr): make failures fatal after experiment.