python · gpshead · Mar 28, 2026 · Mar 16, 2026 · Mar 28, 2026 · chris-eibl
@@ -351,15 +351,16 @@ def _args_from_interpreter_flags():
    # -X options
    if dev_mode:
        args.extend(('-X', 'dev'))
-    for opt in ('faulthandler', 'tracemalloc', 'importtime',
-                'frozen_modules', 'showrefcount', 'utf8', 'gil'):
-        if opt in xoptions:
-            value = xoptions[opt]
-            if value is True:
-                arg = opt
-            else:
-                arg = '%s=%s' % (opt, value)
-            args.extend(('-X', arg))
+    for opt in sorted(xoptions):
+        if opt == 'dev':
+            # handled above via sys.flags.dev_mode
+            continue
+        value = xoptions[opt]
+        if value is True:
+            arg = opt
+        else:
+            arg = '%s=%s' % (opt, value)
+        args.extend(('-X', arg))

    return args


diff --git a/Lib/test/test_support.py b/Lib/test/test_support.py
@@ -569,12 +569,19 @@ def test_args_from_interpreter_flags(self):
            # -X options
            ['-X', 'dev'],
            ['-Wignore', '-X', 'dev'],
+            ['-X', 'cpu_count=4'],
+            ['-X', 'disable-remote-debug'],
            ['-X', 'faulthandler'],
            ['-X', 'importtime'],
            ['-X', 'importtime=2'],
+            ['-X', 'int_max_str_digits=1000'],
+            ['-X', 'lazy_imports=all'],
+            ['-X', 'no_debug_ranges'],
+            ['-X', 'pycache_prefix=/tmp/pycache'],
            ['-X', 'showrefcount'],
            ['-X', 'tracemalloc'],
            ['-X', 'tracemalloc=3'],
+            ['-X', 'warn_default_encoding'],
        ):
            with self.subTest(opts=opts):
                self.check_options(opts, 'args_from_interpreter_flags')

diff --git a/Misc/NEWS.d/next/Library/2026-03-16-00-00-00.gh-issue-146004.xOptProp.rst b/Misc/NEWS.d/next/Library/2026-03-16-00-00-00.gh-issue-146004.xOptProp.rst
@@ -0,0 +1,9 @@
+All :option:`-X` options from the Python command line are now propagated to
+child processes spawned by :mod:`multiprocessing`, not just a hard-coded
+subset.  This makes the behavior consistent between default "spawn" and
+"forkserver" start methods and the old "fork" start method.  The options
+that were previously not propagated are: ``context_aware_warnings``,
+``cpu_count``, ``disable-remote-debug``, ``int_max_str_digits``,
+``lazy_imports``, ``no_debug_ranges``, ``pathconfig_warnings``, ``perf``,
+``perf_jit``, ``presite``, ``pycache_prefix``, ``thread_inherit_context``,
+and ``warn_default_encoding``.
-Original file line number
+Diff line change
@@ -569,12 +569,19 @@ def test_args_from_interpreter_flags(self):
                 # -X options
                 ['-X', 'dev'],
                 ['-Wignore', '-X', 'dev'],
+                ['-X', 'cpu_count=4'],
+                ['-X', 'disable-remote-debug'],
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            chris-eibl
  

      

      

      


        Mar 28, 2026



      
    

  

  
    
      
          
    
  


        
            
  
      
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      This is documented as
-X disable_remote_debug

with underscores.
Furthermore, -X presite=package.module, -X gil=0,1 and some more aren't listed here.
Not a big issue IMHO, since this just tests that whatever we pass in is returned from args_from_interpreter_flags?
    
  
  



    

        
      
  
  
    
  
  
  
    
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            chris-eibl
  

      

      

      


        Mar 28, 2026



      
    

  

  
    
      
          
    
  


        
            
  
      
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      So an alternative fix for #146580 would be to just remove ['-X', 'pycache_prefix=/tmp/pycache'],?
Sorry, didn't realize earlier, just stumbled over it now ...
    
  
  



    

        
      
  
  
    
  
  
  
    
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                 ['-X', 'faulthandler'],
                 ['-X', 'importtime'],
                 ['-X', 'importtime=2'],
+                ['-X', 'int_max_str_digits=1000'],
+                ['-X', 'lazy_imports=all'],
+                ['-X', 'no_debug_ranges'],
+                ['-X', 'pycache_prefix=/tmp/pycache'],
                 ['-X', 'showrefcount'],
                 ['-X', 'tracemalloc'],
                 ['-X', 'tracemalloc=3'],
+                ['-X', 'warn_default_encoding'],
             ):
                 with self.subTest(opts=opts):
                     self.check_options(opts, 'args_from_interpreter_flags')
-          Expand Down