https://bugs.kde.org/show_bug.cgi?id=338571
--- Comment #40 from Tore Anderson <t...@fud.no> --- Following the release of Fedora 26, I decided to test KMail again and compare it with Mozilla Thunderbird, both using a completely empty UNIX account. tl;dr: Compared to Thunderbird, KMail/Akonadi ends up using a absolutely ridiculous amount of time, CPU, disk space, and network traffic to connect to an IMAP account. Main observations: - KMail needed ~30 minutes to perform the initial sync of all folders, while Thunderbird used <5 minutes*: - The system was completely swamped by Akonadi and MySQL processes. Thunderbird was very modest. - KMail exchanged 1.19 GB of data with the IMAP server. Thunderbird exchanged 128 MB. - Afterwards, the home directory of the KMail test account contained 3842 MB of data, Thunderbird's contained 128 MB. * Unlike KMail, Thunderbird only synced INBOX automatically and its UI usable within seconds. The <5 minutes included manually opening and syncing every single IMAP folder. More details: The test system has a quad-core Intel i5-7300U and 16 GB of RAM. The IMAP server is running Dovecot 2.2.22 and requires TLS. The IMAP accounts contains approx 224.500 messages (4.3 GB of data). The largest folder contains about 43.400 messages. When starting KMail at about 12:30 I cancelled the initial Account Assistant wizard, and selected both "Work Offline" and "Use Less Bandwidth" from the File menu. I then created the IMAP account, making sure to uncheck "Download all messages for offline use" and "Interval mail checking". At 12:35 I selected "Work Online" from the File menu and clicked the "Check Mail" button. At this point, KMail goes to work. The status indicator is showing a progress bar titled "Syncing folder 'x'" which cycles through every folder on the IMAP server. While this goes on, I can see the following processes consistently occupying the top-5 spots in the output of top(1). They are sorted according to which position they typically was found at (although it does change around a bit from refresh to refresh): 1) mysqld 2) akonadiserver 3) akonadi_indexing_agent 4) akonadi_imap_resource 5) kmail The load average jumps up to around 5, and the laptop's fan revs up to max speed. At 13:02 the last "Syncing folder 'x'" progress indicator vanishes. At this point, IMAP network traffic stops and only the "akonadi_indexing_agent" process continue to hog a CPU core. At around 13:05 this process also calms down, the load eventually drops to below 1, and the laptop fan silences. As mentioned above, at this point there had been 1,19 GB of network traffic between the client and the IMAP server. Almost exclusively in the server->client direction. This was measured with iftop(8). The test user's (previously empty) home directory had grown to contain 3842 MB of data. This was almost all divided into these three directories: /home/kmailtest/.local/share/akonadi/db_data : 791 MB /home/kmailtest/.local/share/akonadi/file_db_data : 1360 MB /home/kmailtest/.local/share/akonadi/search_db : 1674 MB The Thunderbird process was started at 13:30. As with KMail, I cancelled the initial wizard and entered offline mode. Then I created the IMAP account, making sure to deselect "Keep messages for this account on this computer". At 13:35 I entered online mode and clicked "Get Messages". This caused it to download all the headers in the modestly-sized INBOX folder, which was done in maybe five seconds. This is IMHO a vastly superior approach to the KMail one of syncing all the remote folders immediately. In order to get a comparable test, I then proceeded to manually open every single IMAP folder, one after the other. Upon entering each folder Thunderbird would download the headers of all messages contained in it. I had walked through all the folders on the servers before 13:40. After this /home/tbirdtest had grown to contain 128 MB of data and iftop(8) had observed 210MB of network traffic between the client and the IMAP server. I will be attaching a few Munin graphs gathered from the laptop as these tests were run. The Thunderbird test isn't really visible, while the KMail one clearly is. I also ran this KMail test yesterday at around 21:30-22:00, which also clearly stands out. The KMail/Akonadi versions installed were: kf5-libkdepim-akonadi-17.04.1-1.fc26.x86_64 kf5-akonadi-notes-17.04.1-1.fc26.x86_64 kf5-akonadi-server-mysql-17.04.1-3.fc26.x86_64 kf5-akonadi-mime-17.04.1-1.fc26.x86_64 kf5-akonadi-contacts-17.04.1-1.fc26.x86_64 kf5-akonadi-search-17.04.1-1.fc26.x86_64 kmail-account-wizard-17.04.1-1.fc26.x86_64 kf5-kmailtransport-17.04.1-1.fc26.x86_64 akonadi-1.13.0-103.fc26.x86_64 kmail-17.04.1-3.fc26.x86_64 kf5-akonadi-calendar-17.04.1-1.fc26.x86_64 kf5-mailimporter-akonadi-17.04.1-1.fc26.x86_64 kdepimlibs-akonadi-4.14.10-18.fc26.x86_64 akonadi-import-wizard-17.04.1-1.fc26.x86_64 kf5-akonadi-server-17.04.1-3.fc26.x86_64 kmail-libs-17.04.1-3.fc26.x86_64 kf5-kmailtransport-akonadi-17.04.1-1.fc26.x86_64 kf5-pimcommon-akonadi-17.04.1-1.fc26.x86_64 Tore -- You are receiving this mail because: You are watching all bug changes.
