User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0

Steps to reproduce:

Click on Inbox of IMAP account.

Actual results:

Seeing hourglass for ever, even after later tries after hours.
See: https://share.firefox.dev/3spw0P7

Only restart of TB helps.

There seems to be a relation to bug 1346060.

Thanks for getting the profile. For https://share.firefox.dev/3spw0P7 most of the activity is:

• nsHostResolver::GetHostToLookup (DNS) and then goes off to the OS
• nsAppShell::ProcessNextNativeEvent > PollWrapper and then goes off to the OS

So pretty much nothing happening in Thunderbird, and also not much going on in gecko.

(In reply to Ulf Zibis from comment #1)

There seems to be a relation to bug 1346060.

I don't understand how. Why do you think that?

(In reply to Wayne Mery (:wsmwk) from comment #2)

(In reply to Ulf Zibis from comment #1)

There seems to be a relation to bug 1346060.

I don't understand how. Why do you think that?

I often have this case, at least once a week. This is the first time, I did a performance profile to post a bug, as I too noticed high CPU use, which also may relate to bug 1549978. Then I always have to restart TB as workaround and then I always have a shut down hang crash. This is, why I suppose a relation to the crash. I'm not sure, if every crash is preceded by a IMAP blocking.
Normally I run TB over several days. In the night I suspend my machine to RAM. This may too be a reason for the problem.

Honza, what would you conclude from comment 2. Misconfiguration?

I'm wondering, why this issue is reported so rarely.
Maybe it is because it's so subtle. If one doesn't know, that there are emails waiting on the server, he doesn't miss them.
I'm working on a 12 years old machine, so maybe is doesn't appear so obviously on newer faster machines, so there is not so much CPU usage, see bug 1707847.

Still seeing this?

(In reply to Wayne Mery (:wsmwk) from comment #7)

Still seeing this?

Yes, but less often.

Hi,
since 2 days one of my IMAP accounts is blocking. Load new messages from this account repetitively does nothing. I opened a new tab with it's INBOX. So since 2 days I see the running hourglass in the tab.
Now I started the profiler, to record what's happening. I clicked "Load new messages" again and then selected the tab. In the message list I then selected one of the 2 days old messages. At this moment surprisingly the download of the missing messages from the last 2 days started.

Here is the profile: https://share.firefox.dev/37FgHdp

With such an old profile, and the issue(s) you describe in bug 1549978, there is great potential for problems to have developed.

Have you tried creating a new profile?
https://support.mozilla.org/en-US/kb/using-multiple-profiles

(In reply to Wayne Mery (:wsmwk) from comment #10)

Have you tried creating a new profile?
https://support.mozilla.org/en-US/kb/using-multiple-profiles

No, not yet. It would be much work to Configure all my settings and plenty of filters etc.
But I have now upgraded to version 91. Maybe it repairs it.

I'm not suggesting you duplicate everything in the new profile (filters for example), mainly just get a few accounts and build from there.

Plus the instances can run side by side, with the new profile running in the background and you still using the old profile.

But yes, let's see what happens with version 91.

(In reply to Wayne Mery (:wsmwk) from comment #12)

I'm not suggesting you duplicate everything in the new profile (filters for example), mainly just get a few accounts and build from there.

Plus the instances can run side by side, with the new profile running in the background and you still using the old profile.

Without filtering I would get a big mess in my messages workflow and even lots of duplicates when running 2 instances in parallel. Even I would suspect, the issue will appear on a default profile. Anyway I should run it for plenty days and also do some parallel actions to even see the blocking.

Unfortunately it is complicated to copy filter settings because of bug 944944.

An additional observation from the last years I can share:
When I change something in an IMAP folder, the blocking stops and new messages were loaded. Such actions can be:

• delete a message
• move a message
• select a message to view in a folder, which is not automatically cached, so it's content gets loaded the first time.
  But this "trick" doesn't success always.