[PATCH] parsers: when available, use a presized dictionary for the file foldmap

[Siddharth Agarwal]

On 04/15/2015 06:35 PM, Augie Fackler wrote:
> On Wed, Apr 15, 2015 at 02:38:52PM -0700, Siddharth Agarwal wrote:
>> # HG changeset patch
>> # User Siddharth Agarwal <sid0 at fb.com>
>> # Date 1429133744 25200
>> #      Wed Apr 15 14:35:44 2015 -0700
>> # Node ID 8ca386e305d52af5e714126173bc15c884bf16fc
>> # Parent  c560d8c687916cb70a6d54c2c9ddcb5c9e457be2
>> parsers: when available, use a presized dictionary for the file foldmap
> It might be interesting to expose a parsers.presizeddict() method to
> our Python code as well.

Probably easiest to do that the moment we drop < 2.6 support.

>
> Queued this, thanks.
>
>> On a repo with over 300,000 files, this speeds up perffilefoldmap:
>>
>> before: wall 0.178421 comb 0.180000 user 0.160000 sys 0.020000 (best of 55)
>> after:  wall 0.164462 comb 0.160000 user 0.140000 sys 0.020000 (best of 59)
>>
>> diff --git a/mercurial/parsers.c b/mercurial/parsers.c
>> --- a/mercurial/parsers.c
>> +++ b/mercurial/parsers.c
>> @@ -205,7 +205,20 @@ static PyObject *make_file_foldmap(PyObj
>>               goto quit;
>>       }
>>
>> +#if PY_VERSION_HEX >= 0x02060000
>> +	/* _PyDict_NewPresized expects a minused parameter, but it actually
>> +        creates a dictionary that's the nearest power of two bigger than the
>> +        parameter. For example, with the initial minused = 1000, the
>> +        dictionary created has size 1024. Of course in a lot of cases that
>> +        can be greater than the maximum load factor Python's dict object
>> +        expects (= 2/3), so as soon as we cross the threshold we'll resize
>> +        anyway. So create a dictionary that's 3/2 the size. Also add some
>> +        more to deal with additions outside this function. */
>> +	file_foldmap = _PyDict_NewPresized((PyDict_Size(dmap) / 5) * 8);
>> +#else
>>       file_foldmap = PyDict_New();
>> +#endif
>> +
>>       if (file_foldmap == NULL)
>>               goto quit;
>>
>> _______________________________________________
>> Mercurial-devel mailing list
>> Mercurial-devel at selenic.com
>> http://selenic.com/mailman/listinfo/mercurial-devel
> _______________________________________________
> Mercurial-devel mailing list
> Mercurial-devel at selenic.com
> http://selenic.com/mailman/listinfo/mercurial-devel