[Bug 243569] Kmail is extremely slow and uses CPU without any reason

[JHF2442]

https://bugs.kde.org/show_bug.cgi?id=243569


JHF2442 <j-kde_bts at joel-hatsch.net> changed:

           What    |Removed                     |Added
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                 CC|                            |j-kde_bts at joel-hatsch.net




--- Comment #5 from JHF2442 <j-kde_bts joel-hatsch net>  2010-11-07 17:53:29 ---
Hello *,

not sure if this is the same issue : in my case the high CPU load is caused by
a "check for mail" on a disconnected imap account, so it is not "without any
reason"

using "connected" imap, the check of the 500+ folders lasts <10s, using the
disconnected imap account type, the update lasts ~10min, with hich (75%) CPU
usage by kmail. I therefore exclude a global issue with the imap server
(dovecot, ubuntu 10.04). It looks however as if the disconnected imap variant
was doing more/different things, which extremely slow down the access.

this happens as well on first as on further checks, so it is not related to
some kind of initial setting of data structures/refresh of information.

clicking on the status progress bar (the blue widget in the bottom right corner
of the kmail window), it shows that ~1 folder/s is refreshed. the displayed
messages are "Retrieving message list", "Checking for validity" and
"synchronization done"

using dovecot's rawlog feature, I see that the disconnected imap uses following
commands to refresh one folder :
2 NAMESPACE
3 LIST "" ""
4 LIST "" "Mailing_lists.XYZ"
5 SELECT "Mailing_lists.XYZ"
6 LIST "" "Mailing_lists.XYZ.%"
7 NOOP
8 UID FETCH 1:* (FLAGS RFC822.SIZE)


wheras the "connected" imap account issues :
2 NAMESPACE
3 LIST "" ""
4 LIST "" "Mailing_lists.XYZ"
5 SELECT "Mailing_lists.XYZ"
6 NOOP
7 UID FETCH 4927:* (UID RFC822.SIZE FLAGS ENVELOPE BODY.PEEK[HEADER.FIELDS
(REFERENCES)])

I think the main difference is the last line : disconnected imap fetches ALL
messages, which results in higher effort per folder.

Could somebody check why this is implemented like that ?

Thanks

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