Speed up builds by increasing threads for builds

Generally, OpenStack CI infrastructure workers will typically have
8 cores therefore by hardcoding the threads to 4, we miss out on
valuable CPU power that can speed up builds.

This patch sets the number of threads when running tests between
the higher number of 4 (original value) or the number of CPU cores.

Change-Id: I857507d08d91ddb5e0bccb118d15f2e2bcf4da99

1 files changed, 7 insertions, 1 deletions

diff --git a/tests/test_build.py b/tests/test_build.py
index 260e12e97..b70583748 100644
--- a/tests/test_build.py
+++ b/tests/test_build.py
@@ -11,6 +11,7 @@
 #    under the License.
 
 import abc
+import multiprocessing
 import os
 import sys
 
@@ -34,7 +35,12 @@ class BuildTest(object):
         super(BuildTest, self).setUp()
         self.useFixture(log_fixture.SetLogLevel([__name__],
                                                 logging.logging.INFO))
-        self.build_args = [__name__, "--debug", '--threads', '4']
+
+        self.threads = multiprocessing.cpu_count()
+        if self.threads < 4:
+            self.threads = 4
+
+        self.build_args = [__name__, "--debug", '--threads', str(self.threads)]
 
     @testtools.skipUnless(os.environ.get('DOCKER_BUILD_TEST'),
                           'Skip the docker build test')