pythongh-93584: Avoid file race condition in build process

Author: tiran

Lib/_bootsubprocess.py

@@ -4,6 +4,7 @@
 subprocess is unavailable. setup.py is not used on Windows.
 """
 import os
+import time
 
 
 # distutils.spawn used by distutils.command.build_ext
@@ -70,7 +71,9 @@ def check_output(cmd, **kwargs):
     if not _check_cmd(cmd):
         raise ValueError(f"unsupported command: {cmd!r}")
 
-    tmp_filename = "check_output.tmp"
+    # include pid and time stamp to avoid file name clashes with parallel
+    # builds.
+    tmp_filename = f"check_output-{os.getpid()}-{int(time.time() )}.tmp"
     if not isinstance(cmd, str):
         cmd = " ".join(cmd)
     cmd = f"{cmd} >{tmp_filename}"

Misc/NEWS.d/next/Build/2022-06-07-16-32-37.gh-issue-93584.QHPiBA.rst

@@ -0,0 +1,2 @@
+Avoid file race condition in ``setup.py`` ``add_multiarch_paths()`` method
+and ``_bootsubprocess.check_output()`` function.

setup.py

@@ -10,6 +10,7 @@
 import shlex
 import sys
 import sysconfig
+import time
 import warnings
 from glob import glob, escape
 import _osx_support
@@ -688,9 +689,15 @@ def check_extension_import(self, ext):
     def add_multiarch_paths(self):
         # Debian/Ubuntu multiarch support.
         # https://wiki.ubuntu.com/MultiarchSpec
-        tmpfile = os.path.join(self.build_temp, 'multiarch')
-        if not os.path.exists(self.build_temp):
-            os.makedirs(self.build_temp)
+
+        # Poor man's conflict avoidance. PGO build use $(MAKE), which runs
+        # make in a separate, untracked process. Sometimes main and subproces
+        # run `make sharedmods` at the same time. One process removes
+        # "multiarch" file of the other process.
+        tmpfile = os.path.join(
+            self.build_temp, f"multiarch-{os.getpid()}-{int(time.time() )}.tmp"
+        )
+        os.makedirs(self.build_temp, exist_ok=True)
         ret = run_command(
             '%s -print-multiarch > %s 2> /dev/null' % (CC, tmpfile))
         multiarch_path_component = ''
@@ -713,9 +720,7 @@ def add_multiarch_paths(self):
         opt = ''
         if CROSS_COMPILING:
             opt = '-t' + sysconfig.get_config_var('HOST_GNU_TYPE')
-        tmpfile = os.path.join(self.build_temp, 'multiarch')
-        if not os.path.exists(self.build_temp):
-            os.makedirs(self.build_temp)
+        os.makedirs(self.build_temp, exist_ok=True)
         ret = run_command(
             'dpkg-architecture %s -qDEB_HOST_MULTIARCH > %s 2> /dev/null' %
             (opt, tmpfile))