Start tests as they're discovered

ats/cwd.py

@@ -0,0 +1,28 @@
+"""Thread-safe helpers for process current-working-directory changes."""
+from contextlib import contextmanager
+import os
+import threading
+
+
+_cwd_lock = threading.RLock()
+
+
+@contextmanager
+def chdir(path):
+    """Temporarily change process cwd while holding the global cwd lock.
+
+    Args:
+        path (str): Directory to make the process current-working-directory
+            while the context is active.
+
+    Yields:
+        None.  The previous current-working-directory is restored when the
+        context exits.
+    """
+    with _cwd_lock:
+        here = os.getcwd()
+        os.chdir(path)
+        try:
+            yield
+        finally:
+            os.chdir(here)

ats/machines.py

@@ -3,6 +3,7 @@
 import subprocess, sys, os, time, shlex
 from ats.atsut import RUNNING, TIMEDOUT, PASSED, FAILED, LSFERROR, \
      SKIPPED, HALTED, AtsError
+from ats.cwd import chdir
 from ats.log import log, terminal
 from shutil import copytree, ignore_patterns
 
@@ -291,14 +292,12 @@ def testEnded(self, test, status):
         verbose                     = configuration.options.debug
 
         if not (globalPostrunScript == "unset"):
-            here = os.getcwd()
-            os.chdir(test.directory)
-            if os.path.exists(globalPostrunScript):
-                self._executePreOrPostRunScript(globalPostrunScript, test, verbose, globalPostrunScript_outname)
-            else:
-                log("ATS ERROR: globalPostrunScript %s not found" % (globalPostrunScript), echo=True)
-                sys.exit(-1)
-            os.chdir(here)
+            with chdir(test.directory):
+                if os.path.exists(globalPostrunScript):
+                    self._executePreOrPostRunScript(globalPostrunScript, test, verbose, globalPostrunScript_outname)
+                else:
+                    log("ATS ERROR: globalPostrunScript %s not found" % (globalPostrunScript), echo=True)
+                    sys.exit(-1)
 
         self.numberTestsRunning -= 1
         if MachineCore.debugClass or MachineCore.canRunNow_debugClass:
@@ -557,14 +556,12 @@ def _launch(self, test):
 
 
         if not (globalPrerunScript == "unset"):
-            here = os.getcwd()
-            os.chdir(test.directory)
-            if os.path.exists(globalPrerunScript):
-                self._executePreOrPostRunScript(globalPrerunScript, test, verbose, globalPrerunScript_outname)
-            else:
-                log("ATS ERROR: globalPrerunScript %s not found" % (globalPrerunScript), echo=True)
-                sys.exit(-1)
-            os.chdir(here)
+            with chdir(test.directory):
+                if os.path.exists(globalPrerunScript):
+                    self._executePreOrPostRunScript(globalPrerunScript, test, verbose, globalPrerunScript_outname)
+                else:
+                    log("ATS ERROR: globalPrerunScript %s not found" % (globalPrerunScript), echo=True)
+                    sys.exit(-1)
 
         try:
             Eadd    = test.options.get('env', None)