IOError: request data read error

[Chunlei Wu]

Hi,

We have a web app running on Django 1.0 / modwsgi 2.0 / Apache
2.2.3. Sparsely, about 2~3 times a week, I receive emails about
IOError as below:

Traceback (most recent call last):

File "/projects/prod/python/2.5.1/lib/python2.5/site-packages/django/
core/handlers/base.py", line 86, in get_response
response = callback(request, *callback_args, **callback_kwargs)

File "/projects/prod/www/views.py", line 159, in index
searchby = request.POST.get('searchby', 'searchbyanno').lower()
# valid values: searchbyanno or searchbyinterval

File "/projects/prod/python/2.5.1/lib/python2.5/site-packages/django/
core/handlers/wsgi.py", line 169, in _get_post
self._load_post_and_files()

File "/projects/prod/python/2.5.1/lib/python2.5/site-packages/django/
core/handlers/wsgi.py", line 149, in _load_post_and_files
self._post, self._files = http.QueryDict(self.raw_post_data,
encoding=self._encoding), datastructures.MultiValueDict()

File "/projects/prod/python/2.5.1/lib/python2.5/site-packages/django/
core/handlers/wsgi.py", line 203, in _get_raw_post_data
size=content_length)

File "/projects/prod/python/2.5.1/lib/python2.5/site-packages/django/
core/handlers/wsgi.py", line 69, in safe_copyfileobj
buf = fsrc.read(min(length, size))

IOError: request data read error


Mostly it happens on the root URL, but there is a case from other URL.
I suspect that it is related to the network connection problem, but I
can not re-produce it. Can anybody explain what doe this error mean
exactly? Thanks.

Chunlei

[Graham Dumpleton]

On Jan 6, 4:41 am, Chunlei Wu <reill...@gmail.com> wrote:
> Hi,
>
>        We have a web app running on Django 1.0 / modwsgi 2.0 / Apache

Latest mod_wsgi is 2.3, you should really think about upgrading. :-)

> 2.2.3. Sparsely, about 2~3 times a week, I receive emails about
> IOError as below:
>

> ...

>   File "/projects/prod/python/2.5.1/lib/python2.5/site-packages/django/
> core/handlers/wsgi.py", line 69, in safe_copyfileobj
>     buf = fsrc.read(min(length, size))
>
> IOError: request data read error
>
> Mostly it happens on the root URL, but there is a case from other URL.
> I suspect that it is related to the network connection problem, but I
> can not re-produce it. Can anybody explain what  doe this error mean
> exactly? Thanks.

It means that low level Apache functions returned an error when trying
to read request content.

Unfortunately, the particular Apache function used to get the request
content is one that effectively looses the even lower level Apache
error number which would be useful in qualifying what caused the
problem. In other words, the Apache function just says there was an
error and not what it was. Technically some different set of Apache
functions could be used to do the same thing, without loss of the
error code when a problem does occur, but that is a bit trickier and
involves more work. Changing how it is done might occur, but not soon.

More than likely though, it is a variation on another error that can
come back when reading request content as described in:

http://code.google.com/p/modwsgi/issues/detail?id=29

That one can occur when user/client aborts the connection. This can
occur when they are trigger happy on the reload button.

To try and reproduce it, perhaps perform a file upload and before it
has completed keep pressing the reload button for the page.

Graham

[Chunlei Wu]

Thanks a lot Graham. I will upgrade my modwsgi to v2.3. Looking
forward to the v3.0 to see if the fix on issue #29 will fix my problem
as well.

Chunlei

On Jan 5, 3:40 pm, Graham Dumpleton <Graham.Dumple...@gmail.com>
wrote:

[Graham Dumpleton]

On Jan 7, 4:04 am, Chunlei Wu <reill...@gmail.com> wrote:
> Thanks a lot Graham. I will upgrade my modwsgi to v2.3. Looking
> forward to the v3.0 to see if the fix on issue #29 will fix my problem
> as well.

Actually, my reference to issue #29 is a bit wrong. That issue relates
to connection being closed when trying to write the response. In your
case the issue is when connection is closed or has a problem when
reading the response. The reduction in unnecessary logging in that
issue will not change what you are seeing. When a read fails you will
still see an exception being raised and if your code or Django isn't
doing anything specifically about that and just passing it back, you
will get the same behaviour as you do now.

Graham