[Kde-pim] Mail loss when moving email while it is downloaded

[Martin Steigerwald]

Hello Sven, hello everyone,

Am Sonntag, 12. Februar 2012 schrieb Sven Burmeister:
> Am Samstag, 11. Februar 2012, 13:18:28 schrieb Volker Krause:
> > It's the same scenario we saw some time ago already, with more
> > obvious move/copy operations. The reason was a combination of nested
> > transactions and the wrong transaction isolation levels. The
> > attached patch against Akonadi master addresses this more generally
> > than our fixes/workarounds from back then.
> >
> > 
> >
> > I'd appreciate some testing by someone who is able to reliably
> > reproduce this problem (I never was, making it very hard to debug
> > this).
> 
> This patch does not fix the issue completely.
> 
> To re-produce:
> 
> 1. set View > Attachments to Icons
> 
> 2. send an email with a large attachment to your imap (not dimap)
> account
> 
> 3. click on the email in the message list, kmail shows "loading" in
> the  preview pane
> 
> 4. press DEL to move it to the local trash while it is still loading
> 
> 5. select a few other read and unread emails and press DEL, kmail will
> only  mark them as deleted but the "loading" is still visible in the
> preview pane and no message was removed from the message list yet.
> (your internet connection must be that slow)

Maybe some stuff from the Linux performance analysis and tuning trainings 
helps with debugging this. It is possible to simulate a slow internet 
connection for testing purposes:

merkaba:~> cd /proc/sys/net/ipv4
merkaba:/proc/sys/net/ipv4> cat tcp_rmem 
4096    87380   4194304
merkaba:/proc/sys/net/ipv4> cat tcp_window_scaling 
1
merkaba:/proc/sys/net/ipv4> echo "0" > tcp_window_scaling 
merkaba:/proc/sys/net/ipv4> echo "4096 4096 4096" > tcp_rmem 
merkaba:/proc/sys/net/ipv4>


martin at merkaba:~> wget 
http://www.kernel.org/pub/linux/kernel/v3.0/linux-3.2.5.tar.gz
--2012-02-12 22:27:26--  
http://www.kernel.org/pub/linux/kernel/v3.0/linux-3.2.5.tar.gz
Auflösen des Hostnamen »www.kernel.org (www.kernel.org)«... 149.20.4.69
Verbindungsaufbau zu www.kernel.org (www.kernel.org)|149.20.4.69|:80... 
verbunden.
HTTP-Anforderung gesendet, warte auf Antwort... 200 OK
Länge: 98637311 (94M) [application/x-gzip]
In »»linux-3.2.5.tar.gz.1«« speichern.

 0% [                                                 ] 77.448      
7,43K/s  ETA 3h 28m  ^C
martin at merkaba:~#130>

(versus 1500 KB/s or so when its not limited)


To undo restore the old values. With echoing the low value to all three 
values in tcp_rmem disabling window scaling explicitely should not even be 
needed.

You can adjust speed by using different values for tcp_rmem. Values lower 
than 4096 are possible. It is possible to reduce transfer speed to about 
10-20 bytes per second, before it eventually is not even possible to build 
up a TCP/IP connection at all.

Ciao,
-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7
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