[test-runner] Move test case processing beyond the multi-process boundary.

tools/testrunner/local/testsuite.py

Index: tools/testrunner/local/testsuite.py
diff --git a/tools/testrunner/local/testsuite.py b/tools/testrunner/local/testsuite.py
index dd654c30350ab404a7f85dcae9851017d211b51f..eccd98d0c711b35552ab059c63fbfd653d54cf63 100644
--- a/tools/testrunner/local/testsuite.py
+++ b/tools/testrunner/local/testsuite.py
@@ -88,21 +88,27 @@ class VariantGenerator(object):
 class TestSuite(object):
 
   @staticmethod
-  def LoadTestSuite(root):
+  def LoadTestSuite(root, global_init=True):
     name = root.split(os.path.sep)[-1]
     f = None
     try:
       (f, pathname, description) = imp.find_module("testcfg", [root])
       module = imp.load_module("testcfg", f, pathname, description)
-      return module.GetSuite(name, root)
+      suite =  module.GetSuite(name, root)
     except ImportError:
       # Use default if no testcfg is present.
-      return GoogleTestSuite(name, root)
+      suite = GoogleTestSuite(name, root)
     finally:
       if f:
         f.close()
+    if global_init:
+      suite.global_initialization()
+    return suite
 
   def __init__(self, name, root):
+    # Note: This might be called concurrently from different processes. Global
+    # state (e.g. harddisk state) should be initialized in
+    # 'global_initialization' below.
     self.name = name  # string
     self.root = root  # string containing path
     self.tests = None  # list of TestCase objects
@@ -110,6 +116,12 @@ class TestSuite(object):
     self.wildcards = None  # dictionary mapping test paths to list of outcomes
     self.total_duration = None  # float, assigned on demand
 
+  def global_initialization(self):

[Jakob Kummerow, 2015/11/27 10:09:00]

I'd keep the original LoadTestSuite and __init__ without any modifications, make
this a standalone method "SetupWorkingDirectory()", and call it from
run-tests.py around line 605:

    suite = testsuite.TestSuite.LoadTestSuite(
        os.path.join(BASE_DIR, "test", root))
    if suite:
+     suite.SetupWorkingDirectory()
      suites.append(suite)

[Michael Achenbach, 2015/11/27 10:31:21]

Method name ack. Regarding calling: I'll have to add it to three different
places then: run-test, run-deopt and network_execution endpoint. Is that ok? It
would be a bit scattered.

[Jakob Kummerow, 2015/11/27 10:34:41]

Hm... that's a bit less elegant than I was hoping, but I'd still prefer an
explicit call over an implicit side effect.

[Michael Achenbach, 2015/11/27 10:58:29]

Done.

+    # This is called once per test suite object in a multi-process setting.
+    # Logic that is not multi-process-safe can go here, e.g. set up of a
+    # working directory for the suite.
+    pass
+
   def shell(self):
     return "d8"