[Bug 157946] New: timeout while POP due to haevy swapping: kontact dies -- all mails downloaded a second time. seenUidList is nulled.

[reisenweber at web.de]

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http://bugs.kde.org/show_bug.cgi?id=157946         
           Summary: timeout while POP due to haevy swapping: kontact dies --
                    all mails downloaded a second time. seenUidList is
                    nulled.
           Product: kmail
           Version: unspecified
          Platform: unspecified
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: crash
          Priority: NOR
         Component: general
        AssignedTo: kdepim-bugs kde org
        ReportedBy: reisenweber web de


Version:           1.9.6 (enterprise 20070904.708012) (using 3.5.7 "release 72.6" , openSUSE 10.3)
Compiler:          Target: i586-suse-linux
OS:                Linux (i686) release 2.6.22.13-0.3-default

Prerequisites/Preset:
POP3 account, msgs stay on server, (about 2500 msgs/25Meg on server).
Old slow, short on RAM, system (swap fill never >30% though!). 

Reproduce (occurred >1 times. Though it's a timing issue, hard to reproduce - maybe with SIGSTOP KMail, or Netfilters):
When there occurs to be heavy swapping during KMail incidentally polling POP3-account (95% swap, 5% user CPU),  it says:
o- Error requester "server does not support UIDL (UDML? sth) command. ... will not work!" **)
o- i click "abort message download" at bottom right some times (because i know what will follow), then i click "ok" on error-requester **)
o- COMPLETE KONTACT SILENTLY DIES
o- #!#!# the error #!#!#:
~/.kde/share/kmail/<user> <serverdomain>: pop <serverdomain>:995 is void. 
seenUidList=<nullstring>
size before: ~121k, size after error: ~70byte

Error also appeared without the steps marked **)


resulting problems: _all_msgs_ are downloaded a second time, to restore seenUidList. 


nature of problem: <!>never use timeout while polling POP to reset seenUidList</!> Keep backup!
On some timeout/lowmem situations Kontact dies without any further notice (no coredump or anything, just like ^Q). Sometimes it coredumps (SIG11) on similar situation.

seen identically in SuSE10.1 (about 2 years old) version of Kontact

workaround: 
o- avoid lowmem/high-cpu-load when polling POP3.
o- when error happens: CANCEL DOWNLOAD IMMEDIATELY! Create filter to download all msgs older 1day to a temporary mail dir. Poll. (Disable filter. I keep it for catching errors during unattended polls)
o- *OR* CANCEL DOWNLOAD IMMEDIATELY! restore ~/.kde/share/kmail/<user> <serverdomain>* from yesterday's backup.
o- then use <CTRL>+* to delete doublettes


jOERG