fileset, revset: do not use global parser object for thread safety parse() cannot be called at the same time because a parser object keeps its states. This is no problem for command-line hg client, but it would cause strange errors in multi-threaded hgweb. Creating parser object is not too expensive. original: % python -m timeit -s 'from mercurial import revset' 'revset.parse("0::tip")' 100000 loops, best of 3: 11.3 usec per loop thread-safe: % python -m timeit -s 'from mercurial import revset' 'revset.parse("0::tip")' 100000 loops, best of 3: 13.1 usec per loop

--- a/mercurial/fileset.py	Wed Dec 04 13:42:28 2013 -0600
+++ b/mercurial/fileset.py	Sat Dec 21 12:44:19 2013 +0900
@@ -78,7 +78,9 @@
         pos += 1
     yield ('end', None, pos)
 
-parse = parser.parser(tokenize, elements).parse
+def parse(expr):
+    p = parser.parser(tokenize, elements)
+    return p.parse(expr)
 
 def getstring(x, err):
     if x and (x[0] == 'string' or x[0] == 'symbol'):