Hi Lorenz,

On 01.03.19 22:42, Lorenz Pressler (lor...@pressler.pro) wrote:
yes, this made indeed a difference; it's about ~20-30% faster.
response time taken from the debug log is now ~500-1200ms.

as expected, I would say. ;-) Thank you for testing and your feedback.

I am not sure why though or I am misunderstanding what this is doing.

If this parameter is not set, the default setting is effective, which means IMAP pooling is disabled. In this case SOGo has to log in _and_ especially out for every access to/from the IMAP server and so permanently establishes new sessions to Dovecot. A typical log extract would look like this (while clicking in the web interface):

--- snip ---
2019-03-02 10:49:32 imap-login: Info: Login: user=<f...@example.com>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=15163, secured, session=<Uw69cBmDGMl/AAAB>
2019-03-02 10:49:32 imap(f...@example.com): Info: Logged out in=222 out=1607

2019-03-02 10:49:37 imap-login: Info: Login: user=<f...@example.com>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=15167, secured, session=<3WMIcRmDIsl/AAAB>
2019-03-02 10:49:37 imap(f...@example.com): Info: Logged out in=331 out=2116

2019-03-02 10:49:39 imap-login: Info: Login: user=<f...@example.com>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=15169, secured, session=<xSkqcRmDKMl/AAAB>
2019-03-02 10:49:39 imap(f...@example.com): Info: Logged out in=331 out=2116

2019-03-02 10:49:42 imap-login: Info: Login: user=<f...@example.com>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=15171, secured, session=<3ctbcRmDLMl/AAAB>
2019-03-02 10:49:43 imap(f...@example.com): Info: Logged out in=307 out=4075
--- snip ---

In contrast to that, if you set 'NGImap4DisableIMAP4Pooling = NO;' then the pooling is activated, SOGo keeps the current connection open and so _no_ new logins are necessary every time you access a folder or e-mail. In the Dovecot log you'll only see one login and that's it. The down side is, that there will be more simultaneous open connections to Dovecot.

I'm also new to SOGo and hope that my understanding of this mechanism is correct. I don't know exactly if and when timeouts on SOGo and Dovecot regarding the IMAP connection are taking effect (at least there is some information in the RFC's and the Dovecot Wiki). According to the Dovecot log it seems that SOGo logs out after about 5 minutes of inactivity in the web frontend (but I didn't check this exactly).

Well, this test was mainly for isolation and confirmation of one possible reason for the performance bottleneck - the slow IMAP login/access. And with changing this parameter we can indeed mitigate this problem. But for me it's unclear, why the login resp. access to Dovecot takes so long compared to the same procedure using Thunderbird or OpenSSL/fetching as IMAP clients. Perhaps there are some SOGo experts which have any idea how to narrow down this further and have tuning tips?

By way of comparison: in the sogo.log of my server (Debian, 2 GB RAM with software components like on your system and with 'NGImap4DisableIMAP4Pooling = NO;') I can see IMAP access times on an average of 0,1 s, if an initial IMAP login was necessary before then this takes approx. 0,4 s.

And BTW: it doesn't suprise me that your access to address book and calendar is working well, as they are stored exclusively in the MariaDB and this access is something completely different.

Best regards,
Markus
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