1237656 - Change default value of maximum number of server connections to cache in IMAP

Status: RESOLVED INVALID

(Thunderbird :: Account Manager, defect)

Description

[monperrus]

The default value of 5 IMAP connections for  "Maximum number of server connections to cache" causes many problems in particular with respect to IDLE and CONDSTORE. 

A known workaround is to set it to 1.
 
What about setting to 1 by default?

Comment 1

[:aceman]

Is there a good page with descriptions of the known problems?

Comment 2

[Kent James (:rkent)]

For the vast majority of users, performance is better if we cache multiple connections, so it is had to justify a setting of 1, which effectively eliminates multiple connection support for most users (who will not change the default).

Comment 3

[Wayne Mery (:wsmwk)]

(In reply to martin.monperrus from comment #0)
> The default value of 5 IMAP connections for  "Maximum number of server
> connections to cache" causes many problems in particular with respect to
> IDLE and CONDSTORE. 

with *specific* mail servers?  
or all servers?
how so?

Comment 4

[monperrus]

> with *specific* mail servers? or all servers? how so?
I don't know. My claim is based on many comments about various channels, e.g. https://support.mozilla.org/en-US/questions/1082511.

> For the vast majority of users, performance is better if we cache multiple connections
In what situation? Are there any benchmarks?

Comment 5

[Kent James (:rkent)]

(In reply to martin.monperrus from comment #4)

> 
> > For the vast majority of users, performance is better if we cache multiple connections
> In what situation? Are there any benchmarks?

I do not have any benchmarks. But if you try to start a new IMAP operation (say by clicking on a folder) while an existing IMAP operation is in process, with a single connection you are blocked.

Comment 6

[monperrus]

> if you try to start a new IMAP operation (say by clicking on a folder) while an existing IMAP operation is in process, with a single connection you are blocked.
Does it mean that the change will be noticed only by users who do parallel long-running operations?

Comment 7

[monperrus]

Are two cached connections equivalent to two connections on two different devices?

If CONDSTORE is enabled and you have two connections, what if you set a message's flag with connection #1 and the flags are read again just after with connection #2?

Comment 8

[Wayne Mery (:wsmwk)]

I've loosely followed imap cache connection issues over the years, and I don't recall bienvenu ever stating he thought the default should be changed from 5.  So I don't foresee us changing the default that has been adequate many years to handle outlier issues, which are rare and have mostly been because of poorly behaving servers.

We have many important issues so I don't anticipate others spending time to advance your cause. If you believe there is a basis for making an intelligent change, then you are going to need to do significant research to a) demonstrate that need, b) the rationale for the value chosen to replace "5" and that it works for all users and c) (by implication) show to others that you have a solid technical understanding of the issues involved.

Comment 9

[monperrus]

There are a number of long-standing bugs that may be partially caused, or "fostered", by this setting:
- notification and idle related bugs https://bugzilla.mozilla.org/buglist.cgi?quicksearch=idle+imap
- condstore related bugs https://bugzilla.mozilla.org/buglist.cgi?quicksearch=idle+imap
- unable to copy on send (Bug 546728, Bug 543746) 
- flags not propagated (e.g. bug 1077998) 

If this is wrong, I'd be happy to close this issue.

Comment 10

[Wayne Mery (:wsmwk)]

Most of those bugs are not about cached connections.  And if any do impact this bug, our preference is always to fix the cause (i.e. the other bug) rather than tweak something as a workaround. So I suggest focusing on determing which of these other issues might be causing your problem.

Comment 11

[monperrus]

Thanks for the clarification. Closing the issue.