[test] Load the same suites in sub and parent test processes

Before this fix, all existing suites would get wastefully initialized in each subprocess.

Bug: v8:6375
Change-Id: I68d961cde143754724735aecbac605852f89c7d9
Reviewed-on: https://chromium-review.googlesource.com/500187Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45188}

tools/testrunner/local/execution.py

@@ -62,17 +62,18 @@ ProcessContext = collections.namedtuple(
     "process_context", ["suites", "context"])
 
 
-def MakeProcessContext(context):
+def MakeProcessContext(context, suite_names):
   """Generate a process-local context.
 
   This reloads all suites per process and stores the global context.
 
   Args:
     context: The global context from the test runner.
+    suite_names (list of str): Suite names as loaded by the parent process.
+        Load the same suites in each subprocess.
   """
-  suite_paths = utils.GetSuitePaths(TEST_DIR)
   suites = {}
-  for root in suite_paths:
+  for root in suite_names:
     # Don't reinitialize global state as this is concurrently called from
     # different processes.
     suite = testsuite.TestSuite.LoadTestSuite(
@@ -198,7 +199,8 @@ class Runner(object):
     self.perfdata = self.perf_data_manager.GetStore(context.arch, context.mode)
     self.perf_failures = False
     self.printed_allocations = False
-    self.tests = [ t for s in suites for t in s.tests ]
+    self.tests = [t for s in suites for t in s.tests]
+    self.suite_names = [s.name for s in suites]
 
     # Always pre-sort by status file, slowest tests first.
     slow_key = lambda t: statusfile.IsSlow(t.outcomes)
@@ -353,7 +355,7 @@ class Runner(object):
           fn=RunTest,
           gen=gen_tests(),
           process_context_fn=MakeProcessContext,
-          process_context_args=[self.context],
+          process_context_args=[self.context, self.suite_names],
       )
       for result in it:
         if result.heartbeat: