reading mail with large attachment consumes high cpu

reading mail with large attachment consumes high cpu

[Leo]

Hi there,

I'm not sure if this is a bug. I use Gnus to read email from IMAP
server. However recently after an upgrade to No Gnus 0.6 on
2006-10-20, I found reading emails with attachment larger than 1M
really painful. My cpu is put to full spin until the whole mail is
loaded. The loading seems quite long though I have a high-speed
internet connection (100M). And I didn't notice this problem with Gnus
5.11.

My system is:
GNU Emacs 23.0.0.1 (i686-pc-linux-gnu, GTK+ Version 2.8.20) of
2006-10-04

-- 
Leo

Re: reading mail with large attachment consumes high cpu

[Leo]

* Leo (2006-10-28 15:06 +0100) said:
  ^^^
> Hi there,
>
> I'm not sure if this is a bug. I use Gnus to read email from IMAP
> server. However recently after an upgrade to No Gnus 0.6 on
> 2006-10-20, I found reading emails with attachment larger than 1M
> really painful. My cpu is put to full spin until the whole mail is
> loaded. The loading seems quite long though I have a high-speed
> internet connection (100M). And I didn't notice this problem with Gnus
> 5.11.
>
> My system is:
> GNU Emacs 23.0.0.1 (i686-pc-linux-gnu, GTK+ Version 2.8.20) of
> 2006-10-04

It actually happens in Gnus 5.11. Is this a known problem?

-- 
Leo <sdl.web AT gmail.com>                         (GPG Key: 9283AA3F)

Re: reading mail with large attachment consumes high cpu

[Emilio Jesús Gallego Arias]

Hi!

Leo <sdl.web@gmail.com> writes:

>> I'm not sure if this is a bug. I use Gnus to read email from IMAP
>> server. However recently after an upgrade to No Gnus 0.6 on
>> 2006-10-20, I found reading emails with attachment larger than 1M
>> really painful. My cpu is put to full spin until the whole mail is
>> loaded. The loading seems quite long though I have a high-speed
>> internet connection (100M). And I didn't notice this problem with Gnus
>> 5.11.

I had the same problem, and i traced it to gnutls reading from the
server just one char at a time, waking emacs for every char in the
encoded attachment. openssl didn't suffer from the same bug, it could
read bigger chunks from the server, so changing `nnimap-stream` from
tls to ssl in my imap config solved it.

I hope this helps,

Emilio

Re: reading mail with large attachment consumes high cpu

[Leo]

* Emilio Jesús Gallego Arias (2007-01-08 03:13 +0100) said:
  ^^^^^^^^^^^^^^^^^^^^^^^^^^
>>> I'm not sure if this is a bug. I use Gnus to read email from IMAP
>>> server. However recently after an upgrade to No Gnus 0.6 on
>>> 2006-10-20, I found reading emails with attachment larger than 1M
>>> really painful. My cpu is put to full spin until the whole mail is
>>> loaded. The loading seems quite long though I have a high-speed
>>> internet connection (100M). And I didn't notice this problem with Gnus
>>> 5.11.
>
> I had the same problem, and i traced it to gnutls reading from the
> server just one char at a time, waking emacs for every char in the
> encoded attachment. openssl didn't suffer from the same bug, it could
> read bigger chunks from the server, so changing `nnimap-stream` from
> tls to ssl in my imap config solved it.
>
> I hope this helps,
>
> Emilio

That fixed the problem. The email is loaded much much faster. Thanks
very much, Emilio.

BTW,

Is this documented somewhere in Gnus?

-- 
Leo <sdl.web AT gmail.com>                         (GPG Key: 9283AA3F)

Re: reading mail with large attachment consumes high cpu

[Emilio Jesús Gallego Arias]

Leo <sdl.web@gmail.com> writes:

> BTW,
>
> Is this documented somewhere in Gnus?

Not in any place that I'm aware of. 

But I guess this is a gnutls bug, so maybe we should forward it to
gnutls people. Or maybe gnus should call gnutls-cli with different
parameters. Or maybe the kernel scheduler is the one to blame.

This bug is not easy to reproduce. You need:

* A high speed connection to your server.
* A linux kernel with specific scheduling behavior.
* Any recent gnus.
* Emacs {22,23}?

Then set up a imap news source using gnutls-cli and gnus will read the
mail char by char.

It would be good if anyone could test with emacs21, maybe a change in
emacs 22 process handling is what is causing the slowdown.

Regards,

Emilio

Re: reading mail with large attachment consumes high cpu

[Leo]

Hi Emilio,

* Emilio Jesús Gallego Arias (2007/01/08) said:

> Leo <sdl.web@gmail.com> writes:
>
>> BTW,
>>
>> Is this documented somewhere in Gnus?
>
> Not in any place that I'm aware of. 

Could someone document this?

> But I guess this is a gnutls bug, so maybe we should forward it to
> gnutls people. Or maybe gnus should call gnutls-cli with different
> parameters. Or maybe the kernel scheduler is the one to blame.

Any comments from Gnus developers?

>
> This bug is not easy to reproduce. You need:
>
> * A high speed connection to your server.
> * A linux kernel with specific scheduling behavior.
> * Any recent gnus.
> * Emacs {22,23}?
>
> Then set up a imap news source using gnutls-cli and gnus will read the
> mail char by char.
>
> It would be good if anyone could test with emacs21, maybe a change in
> emacs 22 process handling is what is causing the slowdown.
>
> Regards,
>
> Emilio

regards,
-- 
Leo <sdl.web AT gmail.com>                         (GPG Key: 9283AA3F)