Avoid using a new temp directory for each parallel test. NFC

It should be fine for all parallel tests to using the same TEMP_DIR.

The only limitation is on tests that use the canonical test directory
(e.g. EMCC_DEBUG).

It looks like we used to use a unique temp directory per process (See #6150).
However that we changes to one-directory-per-test in #18214, although
I don't remember why.

With this change we don't create a new temp directory except for tests
that are marked as `uses_canonical_tmp`

Author: sbc100

test/common.py

@@ -699,6 +699,13 @@ def set_temp_dir(self, temp_dir):
     # Explicitly set dedicated temporary directory for parallel tests
     os.environ['EMCC_TEMP_DIR'] = self.temp_dir
 
+  def reset_temp_dir(self):
+    # Deleting these instance fields will mean that the class field is used
+    # instead.
+    del self.temp_dir
+    del self.canonical_temp_dir
+    del os.environ['EMCC_TEMP_DIR']
+
   def parse_wasm(self, filename):
     wat = self.get_wasm_text(filename)
     imports = []
@@ -797,7 +804,8 @@ def setUp(self):
           self.temp_files_before_run.append(os.path.normpath(os.path.join(root, filename)))
 
     if self.runningInParallel():
-      self.working_dir = tempfile.mkdtemp(prefix='emscripten_test_' + self.__class__.__name__ + '_', dir=self.temp_dir)
+      # When running tests in parallel each test runs it its own new temp directory
+      self.working_dir = tempfile.mkdtemp(prefix='emtest_' + self.__class__.__name__ + '_', dir=self.temp_dir)
     else:
       self.working_dir = path_from_root('out/test')
       if os.path.exists(self.working_dir):

test/parallel_testsuite.py

@@ -53,10 +53,7 @@ def test_failed():
       with lock:
         allowed_failures_counter.value -= 1
 
-  olddir = os.getcwd()
   result = BufferedParallelTestResult(lock, progress_counter, num_tests)
-  temp_dir = tempfile.mkdtemp(prefix='emtest_')
-  test.set_temp_dir(temp_dir)
   try:
     if test.__class__ not in seen_class:
       seen_class.add(test.__class__)
@@ -71,10 +68,6 @@ def test_failed():
   except Exception as e:
     result.addError(test, e)
     test_failed()
-  # Before attempting to delete the tmp dir make sure the current
-  # working directory is not within it.
-  os.chdir(olddir)
-  common.force_delete_dir(temp_dir)
   return result
 
 

test/test_other.py

@@ -19,6 +19,7 @@
 import subprocess
 import sys
 import tarfile
+import tempfile
 import time
 from datetime import datetime
 from functools import wraps
@@ -142,6 +143,13 @@ def uses_canonical_tmp(func):
   """
   @wraps(func)
   def decorated(self, *args, **kwargs):
+    if self.runningInParallel():
+      # Becuase the canical temp directory is global/central location when
+      # tests use it in parallel they need to temporarily override the
+      # temp directory to ovoid clobbering each each.
+      new_temp = tempfile.mkdtemp(prefix='emtest_' + self.__class__.__name__ + '_', dir=self.temp_dir)
+      self.set_temp_dir(new_temp)
+
     # Before running the test completely remove the canonical_tmp
     if os.path.exists(self.canonical_temp_dir):
       shutil.rmtree(self.canonical_temp_dir)
@@ -155,6 +163,8 @@ def decorated(self, *args, **kwargs):
       # test fails we would not clean it up, and if leak detection
       # is set we will show that error instead of the actual one.
       shutil.rmtree(self.canonical_temp_dir)
+      if self.runningInParallel():
+        self.reset_temp_dir()
 
   return decorated