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 97c12f3f6e200a5787d3a682631de8b9f410a1b0..bef04fd982d1505c9b3daf0b505843fb8d13b84e 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
 
   @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):

[ukai, 2016/09/05 05:30:32]

better to have docstring?

[tikuta, 2016/09/05 09:01:55]

Done.

+    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 +70,26 @@ 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
+
+            try:
+              jobs = min(200, multiprocessing.cpu_count() * 10)
+            except NotImplementedError:
+              jobs = 50
+
+            print jobs
+            """,
+            stdout=self.m.raw_io.output(),
+            step_test_data=(
+                lambda: self.m.raw_io.test_api.stream_output('50\n'))
+          )
+          self._goma_jobs = int(step_result.stdout)
+          if self.m.platform.is_linux:

[ukai, 2016/09/05 05:30:32]

no need to run python.inline above for this case (and when user want to specify
goma_jobs)?

[tikuta, 2016/09/05 09:01:55]

I moved this step into the function to calculate _goma_jobs.

+            self._goma_jobs = 80
+
           return self._goma_dir
         except self.m.step.StepFailure:
           # TODO(phajdan.jr): make failures fatal after experiment.