I've created a JIRA issue for the readline leaks. The one I detail is a
corner case related to what you found, but I don't think the fix below
will help. Take a look at 182 and let me know what you think.
http://issues.apache.org/jira/browse/MODPYTHON-182
I think we should be checking requestobject self->rbuff during the
request cleanup and make sure it really is NULL, just as a safety check.
Alexis Marrero wrote:
> Jim,
>
> I found the culprit!!!
>
> There are two unrelated memory leaks.
>
> The first one is in req_readline().
>
> This code:
>
> /* is there anything left in the rbuff from previous reads? */
> if (self->rbuff_pos < self->rbuff_len) {
> /* if yes, process that first */
> while (self->rbuff_pos < self->rbuff_len) {
> buffer[copied++] = self->rbuff[self->rbuff_pos];
> if ((self->rbuff[self->rbuff_pos++] == '\n') ||
> (copied == len)) {
>
> /* our work is done */
>
> /* resize if necessary */
> if (copied < len)
> if(_PyString_Resize(&result, copied))
> return NULL;
> return result;
> }
> }
> }
>
> Should look like this:
> /* is there anything left in the rbuff from previous reads? */
> if (self->rbuff_pos < self->rbuff_len) {
> /* if yes, process that first */
> while (self->rbuff_pos < self->rbuff_len) {
> buffer[copied++] = self->rbuff[self->rbuff_pos];
> if ((self->rbuff[self->rbuff_pos++] == '\n') ||
> (copied == len)) {
>
> /* our work is done */
>
> /* resize if necessary */
> if (copied < len)
> if(_PyString_Resize(&result, copied))
> return NULL;
> if (self->rbuff_pos >= self->rbuff_len && self->rbuff !=
> NULL)
> {
> free(self->rbuff);
> self->rbuff = NULL;
> }
> return result;
> }
> }
> }
>
> That solves one. Like I mentioned in one of the emails to the mailing
> list, the buffer was not been freed in the last readline().
But not completely - see MODPYTHON-182.
> The second one, for which I don't have a fix yet is apache.make_table()
> in mod_python/util.py line 152. If I comment lines 152, 225, 227 you
> will see that memory doesn't grow. I will keep investigating...
As will I ...
Jim
> Until the next email.
>
> /amn
> Jim Gallacher wrote:
>> I ran my baseline test with 500k requests, and got the following:
>> (Note that all the figures will have an error of +/- 0.1)
>>
>> baseline 500k requests 1.7%
>>
>>
>> So it would seem that there is not a specific problem in readline, or my
>> test case is messed up. FYI here are my 2 handlers:
>>
>> def baseline_handler(req):
>> req.content_type = 'text/plain'
>> req.write('ok baseline:')
>> return apache.OK
>>
>>
>> def readline_handler(req):
>> # the body of the request consists of
>> # '\n'.join([ 'a'*10 for i in xrange(0,10) ])
>> req.content_type = 'text/plain'
>> count = 0
>> while(1):
>> line = req.readline()
>> if not line:
>> break
>> count += 1
>>
>> req.write('ok readline: %d lines read' % count)
>> return apache.OK
>>
>> Jim
>>
>>
>> Jim Gallacher wrote:
>>
>>> I'll have some time to investigate this over the next couple of days. I
>>> ran my leaktest script for FieldStorage and readline, and FieldStorage
>>> certainly still leaks, but I'm not so sure about readline itself.
>>>
>>> baseline 1k requests 1.2%
>>> readline 500k requests 1.6%
>>> fieldstorage 498k requests 10.1%
>>>
>>> The memory consumption figures are for a machine with 512MB ram.
>>>
>>> I'm running my baseline test with 500k requests right now to see if the
>>> 1.6% figure for readline represents a real leak in that function, or if
>>> it is just mod_python itself.
>>>
>>> My memory leak test suite is probably at the point that other people
>>> will find it useful. Once I've written a README explaining its use I'll
>>> commit it to the repository so everybody to play. If you anyone wants to
>>> give it a shot in the interim I can email it to you. Give me shout
>>> offlist.
>>>
>>> I haven't had a chance to look at the code you highlight below, or at
>>> least not closely. The whole req_readline function looks like it will
>>> require a good strong cup of coffee to fully comprehend. ;)
>>>
>>> Jim
>>>
>>> Alexis Marrero wrote:
>>>
>>>> Experimenting on this issue, I noticed that neither of the following
>>>> set
>>>> of "ifs" are ever met:
>>>>
>>>>
>>>> 786 /* Free old rbuff as the old contents have been copied
>>>> over and
>>>> 787 we are about to allocate a new rbuff. Perhaps this could
>>>> be reused
>>>> 788 somehow? */
>>>> 789 if (self->rbuff_pos >= self->rbuff_len && self->rbuff !=
>>>> NULL)
>>>> 790 {
>>>> 791 free(self->rbuff);
>>>> 792 self->rbuff = NULL;
>>>> 793 }
>>>>
>>>>
>>>> --------
>>>>
>>>> 846 /* Free rbuff if we're done with it */
>>>> 847 if (self->rbuff_pos >= self->rbuff_len && self->rbuff !=
>>>> NULL)
>>>> 848 {
>>>> 849 free(self->rbuff);
>>>> 850 self->rbuff = NULL;
>>>> 851 }
>>>>
>>>> I noticed that by putting some statements to write to the output
>>>> stream. They never execute.
>>>>
>>>> /amn
>>>>
>>>> On Aug 10, 2006, at 1:43 PM, Alexis Marrero wrote:
>>>>
>>>>
>>>>> All,
>>>>>
>>>>> We are trying to nail down a memory leak that happens only when
>>>>> documents are POSTed to the server.
>>>>>
>>>>> For testing we have a short script that does:
>>>>>
>>>>> while True:
>>>>> dictionary_of_parameters = {'field1': 'a'*100000}
>>>>> post('url...', dictionary_of_parameters)
>>>>>
>>>>> Then we run "top" on the server and watch the server memory grow
>>>>> without bound. Why do we know that the problem is in
>>>>> request.readline()? If I go to
>>>>> mod_python.util.FieldStorage.read_to_boundary() and add the following
>>>>> statement:
>>>>>
>>>>> def read_to_boundary(...):
>>>>> return True
>>>>> ...
>>>>>
>>>>> as the first executable line in the function the memory does not grow.
>>>>>
>>>>> I have read the req_readline a 1000 time and I can't figure out where
>>>>> the problem is.
>>>>>
>>>>>
>>>>> My config:
>>>>> Python 2.4.1
>>>>> mod_python 3.2.10
>>>>>
>>>>> Our request handler does nothing other than using
>>>>> util.FieldStorage(req) and req.write('hello').
>>>>>
>>>>> I have some suspicion that it has to do with:
>>>>> ....
>>>>> 19 * requestobject.c
>>>>> 20 *
>>>>> 21 * $Id: requestobject.c 420297 2006-07-09 13:53:06Z nlehuen $
>>>>> 22 *
>>>>> 23 */
>>>>> ....
>>>>> 846 /* Free rbuff if we're done with it */
>>>>> 847 if (self->rbuff_pos >= self->rbuff_len && self->rbuff !=
>>>>> NULL)
>>>>> 848 {
>>>>> 849 free(self->rbuff);
>>>>> 850 self->rbuff = NULL;
>>>>> 851 }
>>>>> 852
>>>>>
>>>>> Though, I can't confirm.
>>>>>
>>>>>
>>>>> /amn
>>>>>
>>>>>
>>>
>>
>>
>
>
