[Akonadi] [Bug 443095] New: Moving mails to a different folder is very slow

[Martin Steigerwald]

https://bugs.kde.org/show_bug.cgi?id=443095

            Bug ID: 443095
           Summary: Moving mails to a different folder is very slow
           Product: Akonadi
           Version: 5.18.1
          Platform: Other
                OS: Other
            Status: REPORTED
          Severity: normal
          Priority: NOR
         Component: Maildir Resource
          Assignee: kdepim-bugs at kde.org
          Reporter: Martin at Lichtvoll.de
  Target Milestone: ---

SUMMARY

I moved 13647 from one folder to another.

It took a lot of time. I'd say at least 5 minutes, but I'd say it was longer
than that.

During that time KMail stalled on Akonadi and thus did not display any mail. It
was basically unusable during that time.


STEPS TO REPRODUCE
1. Move 10000 mails from one folder to another
2. Wait
3. Wait
4. Wait
5. …

OBSERVED RESULT

Moving those mails took a lot of time.

In the end I monitored how many mails it adds to the destination maildir folder
each 10 seconds and got this:

% while true; do find -type f | wc -l ; sleep 10 ; done
12426
12645
12936
13216
13445
13609
13647
13647
13647
13647

So it did about 200-300 mails every 10 seconds. Or 20-30 mails a second. This
makes about 454 seconds or 7 minutes for and 34 seconds for moving all of the
mails, in case it started moving mails immediately and it would reach 300 mails
a second consistently. I did not measure the exact total time, but I believe it
was more like 10 minutes or more.


EXPECTED RESULT

Those mails are basically moved within a few seconds.

This is a ThinkPad T14 AMD Gen 1 with AMD Ryzen 7 PRO 4750U 8 core processor
with hyperthreading, 32 GB RAM and 2 TB Samsung 980 Pro SSD. This hardware
really gives no reason to be slow with such a kind of operation.

During the move operation consequently neither the CPU, not even a single core,
nor the SSD was fully utilized.



SOFTWARE/OS VERSIONS

Linux/KDE Plasma: 5.21.5 on Devuan Ceres (aka Debian Sid without Systemd, I use
runit instead)

KDE Plasma Version: 5.21.5
KDE Frameworks Version: 5.86
Qt Version: 5.15.2

Linux Kernel 5.14.7, self compiled.

I am using PostgreSQL backend.

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