[Python-checkins] cpython (merge 3.3 -> default): Issue #16564: Fixed a performance regression relative to Python 3.1 in the

Sat Mar 16 21:56:40 CET 2013

http://hg.python.org/cpython/rev/9d458ded8304
changeset: 82705:9d458ded8304
parent: 82702:5da005db8166
parent: 82704:4b4dddd670d0
user: Serhiy Storchaka <storchaka at gmail.com>
date: Sat Mar 16 22:55:04 2013 +0200
summary:
 Issue #16564: Fixed a performance regression relative to Python 3.1 in the
caching of compiled regular expressions.
files:
 Lib/re.py | 30 ++++++++++++++++++++++++------
 Misc/NEWS | 3 +++
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/Lib/re.py b/Lib/re.py
--- a/Lib/re.py
+++ b/Lib/re.py
@@ -215,8 +215,8 @@
 
 def purge():
 "Clear the regular expression caches"
- _compile.cache_clear()
- _compile_repl.cache_clear()
+ _cache.clear()
+ _cache_repl.clear()
 
 def template(pattern, flags=0):
 "Compile a template pattern, returning a pattern object"
@@ -259,11 +259,18 @@
 # --------------------------------------------------------------------
 # internals
 
+_cache = {}
+_cache_repl = {}
+
 _pattern_type = type(sre_compile.compile("", 0))
 
- at functools.lru_cache(maxsize=512, typed=True)
+_MAXCACHE = 512
 def _compile(pattern, flags):
 # internal: compile pattern
+ try:
+ return _cache[type(pattern), pattern, flags]
+ except KeyError:
+ pass
 if isinstance(pattern, _pattern_type):
 if flags:
 raise ValueError(
@@ -271,12 +278,23 @@
 return pattern
 if not sre_compile.isstring(pattern):
 raise TypeError("first argument must be string or compiled pattern")
- return sre_compile.compile(pattern, flags)
+ p = sre_compile.compile(pattern, flags)
+ if len(_cache) >= _MAXCACHE:
+ _cache.clear()
+ _cache[type(pattern), pattern, flags] = p
+ return p
 
- at functools.lru_cache(maxsize=512)
 def _compile_repl(repl, pattern):
 # internal: compile replacement pattern
- return sre_parse.parse_template(repl, pattern)
+ try:
+ return _cache_repl[repl, pattern]
+ except KeyError:
+ pass
+ p = sre_parse.parse_template(repl, pattern)
+ if len(_cache_repl) >= _MAXCACHE:
+ _cache_repl.clear()
+ _cache_repl[repl, pattern] = p
+ return p
 
 def _expand(pattern, match, template):
 # internal: match.expand implementation hook
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -283,6 +283,9 @@
 Library
 -------
 
+- Issue #16564: Fixed a performance regression relative to Python 3.1 in the
+ caching of compiled regular expressions.
+
 - Added missing FeedParser and BytesFeedParser to email.parser.__all__.
 
 - Issue #17431: Fix missing import of BytesFeedParser in email.parser.
-- 
Repository URL: http://hg.python.org/cpython
