[llvm] 44d14d5 - [lit] Bump up the Windows process cap from 32 to 60

[Arthur Eubanks via llvm-commits]

Author: Arthur Eubanks
Date: 2021-05-07T18:13:38-07:00
New Revision: 44d14d5de6f1f74246bf66dea5538ddc304e6445

URL: https://github.com/llvm/llvm-project/commit/44d14d5de6f1f74246bf66dea5538ddc304e6445
DIFF: https://github.com/llvm/llvm-project/commit/44d14d5de6f1f74246bf66dea5538ddc304e6445.diff

LOG: [lit] Bump up the Windows process cap from 32 to 60

At 61 or over, I see messages like

  File "...\Python\Python39\lib\multiprocessing\connection.py", line 816, in _exhaustive_wait
    res = _winapi.WaitForMultipleObjects(L, False, timeout)

  ValueError: need at most 63 handles, got a sequence of length 64

60 seems to work for me.

If this causes issues for anybody else, feel free to revert.

Added: 
    

Modified: 
    llvm/utils/lit/lit/util.py

Removed: 
    


################################################################################
diff  --git a/llvm/utils/lit/lit/util.py b/llvm/utils/lit/lit/util.py
index 0d8f0040f41c..b02cf2815a79 100644
--- a/llvm/utils/lit/lit/util.py
+++ b/llvm/utils/lit/lit/util.py
@@ -120,10 +120,10 @@ def usable_core_count():
     except AttributeError:
         n = os.cpu_count() or 1
 
-    # On Windows, with more than 32 processes, process creation often fails with
-    # "Too many open files".  FIXME: Check if there's a better fix.
+    # On Windows with more than 60 processes, multiprocessing's call to
+    # _winapi.WaitForMultipleObjects() prints an error and lit hangs.
     if platform.system() == 'Windows':
-        return min(n, 32)
+        return min(n, 60)
 
     return n