dovecot - Oct 2019 - [ext] dovecot 2.3.7.2-1~bionic: Performance issues caused by excessive IO to ~/mdbox/mailboxes/INBOX/dbox-Mails/dovecot.index.tmp

* Ralf Hildebrandt via dovecot <dovecot at
dovecot.org>:
> * Timo Sirainen <timo at sirainen.com>:
> 
> > > BTW: This post is a followup to my "2.3.7 slower than
2.3.6?" post from back in July.
> > 
> > Fixed by
https://github.com/dovecot/core/commit/5e9e09a041b318025fd52db2df25052b60d0fc98
and will be in the soon-to-be-released v2.3.8.
> 
> I stopped 2.3.7, copied over the index files from the ramdisk into
> the physical "realm" and restarted with a fresh 2.3.8. It
probably
> takes a few days to be absolutely sure.
So, in general the performance issues are gone.

But... 

I'm seeing odd hourly spikes almost every hour, on the hour.
You might say: Well yes, that's a cronjob sending lots of mails. But
it isn't. There's not more or less mail coming in at that very moment.

I suspect something in dovecot running every hour (DH key regeneration?)

-- 
Ralf Hildebrandt
  Gesch?ftsbereich IT | Abteilung Netzwerk
  Charit? - Universit?tsmedizin Berlin
  Campus Benjamin Franklin
  Hindenburgdamm 30 | D-12203 Berlin
  Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
  ralf.hildebrandt at charite.de | https://www.charite.de

> On 16/10/2019 13:31 Ralf Hildebrandt via dovecot <dovecot at
dovecot.org> wrote:
> 
>  
> * Ralf Hildebrandt via dovecot <dovecot at dovecot.org>:
> > * Timo Sirainen <timo at sirainen.com>:
> > 
> > > > BTW: This post is a followup to my "2.3.7 slower than
2.3.6?" post from back in July.
> > > 
> > > Fixed by
https://github.com/dovecot/core/commit/5e9e09a041b318025fd52db2df25052b60d0fc98
and will be in the soon-to-be-released v2.3.8.
> > 
> > I stopped 2.3.7, copied over the index files from the ramdisk into
> > the physical "realm" and restarted with a fresh 2.3.8. It
probably
> > takes a few days to be absolutely sure.
> 
> So, in general the performance issues are gone.
> 
> But... 
> 
> I'm seeing odd hourly spikes almost every hour, on the hour.
> You might say: Well yes, that's a cronjob sending lots of mails. But
> it isn't. There's not more or less mail coming in at that very
moment.
> 
> I suspect something in dovecot running every hour (DH key regeneration?)
> 
> -- 
> Ralf Hildebrandt
2.3.7 does not generate DH keys. It's been removed since 2.3.0

Is it possible for you to track and find out which process is causing the peak?

Aki

* Aki Tuomi via dovecot <dovecot at dovecot.org>:
> 2.3.7 does not generate DH keys. It's been removed since 2.3.0
Yes, it was the only periodic process I could think/knew of.
> Is it possible for you to track and find out which process is causing the
peak?
Will try. Next hour :)

-- 
Ralf Hildebrandt
  Gesch?ftsbereich IT | Abteilung Netzwerk
  Charit? - Universit?tsmedizin Berlin
  Campus Benjamin Franklin
  Hindenburgdamm 30 | D-12203 Berlin
  Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
  ralf.hildebrandt at charite.de | https://www.charite.de