lit: Limit number of processes on Windows to 32.

llvm-svn: 256291

utils/lit/lit/util.py

@@ -39,7 +39,9 @@ def detectCPUs():
     if "NUMBER_OF_PROCESSORS" in os.environ:
         ncpus = int(os.environ["NUMBER_OF_PROCESSORS"])
         if ncpus > 0:
-            return ncpus
+            # With more than 32 processes, process creation often fails with
+            # "Too many open files".  FIXME: Check if there's a better fix.
+            return min(ncpus, 32)
     return 1 # Default
 
 def mkdir_p(path):