unnecessary call to time and localtime slows time.mktime

[notherjnelson]

BPO	3289
Nosy	@facundobatista

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2008-07-05.19:35:59.871>
created_at = <Date 2008-07-05.16:13:28.552>
labels = ['extension-modules', 'performance']
title = 'unnecessary call to time and localtime slows time.mktime'
updated_at = <Date 2008-07-05.19:35:59.845>
user = 'https://bugs.python.org/notherjnelson'

bugs.python.org fields:

activity = <Date 2008-07-05.19:35:59.845>
actor = 'facundobatista'
assignee = 'none'
closed = True
closed_date = <Date 2008-07-05.19:35:59.871>
closer = 'facundobatista'
components = ['Extension Modules']
creation = <Date 2008-07-05.16:13:28.552>
creator = 'nother_jnelson'
dependencies = []
files = []
hgrepos = []
issue_num = 3289
keywords = []
message_count = 2.0
messages = ['69283', '69290']
nosy_count = 2.0
nosy_names = ['facundobatista', 'nother_jnelson']
pr_nums = []
priority = 'normal'
resolution = 'accepted'
stage = None
status = 'closed'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue3289'
versions = ['Python 2.6', 'Python 2.5', 'Python 3.0', 'Python 3.1', 'Python 2.7']

[notherjnelson]

Basically, time.mktime calls time and localtime, and then overwrites
those results. Removing these unnecessary calls results in a fairly
noticeable speedup, lower double-digit percentile improvements for
applications that do time parsing, for example.

The patch below is for 2.5, but should apply to more recent versions.

diff --git a/Modules/timemodule.c b/Modules/timemodule.c
index be02ec2..dad235a 100644
--- a/Modules/timemodule.c
+++ b/Modules/timemodule.c
@@ -599,8 +599,6 @@ time_mktime(PyObject *self, PyObject *tup)
 {
        struct tm buf;
        time_t tt;
-       tt = time(&tt);
-       buf = *localtime(&tt);
        if (!gettmarg(tup, &buf))
                return NULL;
        tt = mktime(&buf);

[facundobatista]

Commited in r64745. Thanks for this patch!