[Kde-pim] Akonadi mail performance outlook

[Christian Mollekopf]

On Friday 02 May 2014 11.28:22 Daniel Vrátil wrote:
> On Thursday 01 of May 2014 21:50:40 GEO wrote:
> > Hi,
> > 
> > I am using Akonadi for my mail setup now more intensively than every
> > before
> > and have an mail account with over 10 000 mails atm. This is enough to see
> > some performance issues associated with Akonadi.
> > Here are my top 3 (in the following folder sync means when you have just
> 
> > created your account and you click a folder):
> Hi,
> 
> > 1.) When configuring an imap account (gmail in my case) and you click a
> > folder in kmail, the sync will begin. (No special settings, just created
> > the account with the account wizard). If you click another folder now,
> > nothing happens, it will wait till the initial folder is completely
> > synced.
> > This is not exactly asynchronous and should be addressed.
> 
> This is a known problem with session blocking. Not sure how to solve this
> yet, sorry.
> 
> > 2.) Syncing a folder begins with the oldest messages. If the account is
> > big, it takes some time till you reach the latest message. In reality,
> > you might be more interested in you latest mails at first, so doing that
> > in reverse order would allow you to make use of kmail instantly, without
> > waiting for the sync being complete.
> 
> That's very hard, because in IMAP, you can only query sets of items in
> ascending order (1 being the oldest message), so we can only query 1:* (from
> first to last), not *:1.
> 

That's actually solvable. I already implemented batch processing and UID based 
fetching. This will allow us to implement reverse fetched batches, and 
eventually also limiting the number of mails that are synced offline.
We can't do reverse fetching just yet, because a couple of checks rely on the 
message count, which doesn't take into account that messages could also be 
missing on the lower end.

> However you only do the complete sync once, after that it's only
> incremental, i.e. IMAP resource only requests changes since last check (not
> on Gmail, that has to check all emails in the folder, because their support
> for this feature is broken, but I'm working on it).
> 
> > 3.) During the folder sync, it is nearly impossible to click a message in
> > the folder. You will have to wait extremely long. This should not be the
> > case. Fetching a message content should be completely independent from
> > syncing the folder and should only be limited by physical things like
> > connection speed, disk i/o, cpu load, ram etc.
> 
> It cannot be independent, because in the background it shares the same
> database, where database locking and long transactions (known problem,
> again) lead to retrieval operations taking long time.
> 
> > 4.)  Please implement parallelism in Session and Resources, to avoid the
> > authentication dialog blocking all Akonadi ressources, if one server does
> > not respond.
> 
> That is a hard problem, but something we indeed want to have at some point.
> 

Perhaps we can improve i.e. kmails usecase by using cache-only for the ETM + a 
separate session when on-demand loading a mail for the viewer/editor?

Not sure what else would be blocking, or why we would need it to not be cache-
only.

Cheers,
Christian
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