Bugzilla

Release Note Request (optional, but appreciated)
[Why is this notable]: It should improve the performance of Thunderbird for heavy users. It could also cause problems in particular circumstances, but I don't expect it to.
[Suggested wording]: Changed: criteria for closing idle message databases.
[Links (documentation, blog post, etc)]: None, but I'll write some stuff here for people who find this bug.

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Thunderbird has a message database file for every folder. Once a minute it checks any open databases to see when they were last used, and closes idle databases (more than `mail.db.idle_limit` ms since last use), so that it doesn't have problems with too many open files. If there's still more than `mail.db.max_open` databases open, it closes the oldest ones until that number is reached.

I've changed this. The automatic clean up will now *not* close idle databases if they're larger than `mail.db.keep_open_size` bytes. To bring the number of open databases down it is now more likely to close *small* databases than ones that haven't been used lately. Thunderbird now also avoids closing large databases when switching folders.

Hopefully this will reduce the need to reopen large databases, which can take a long time. You can tune the preferences to suit your situation, at your own risk, of course.

Release Note Request (optional, but appreciated)
[Why is this notable]: It should improve the performance of Thunderbird for heavy users. It could also cause problems in particular circumstances, but I don't expect it to.
[Suggested wording]: Changed: criteria for closing idle message databases.
[Links (documentation, blog post, etc)]: None, but I'll write some stuff here for people who find this bug.

---
Thunderbird has a message database file for every folder. Once a minute it checks any open databases to see when they were last used, and closes idle databases (more than `mail.db.idle_limit` ms since last use), so that it doesn't have problems with too many open files. If there's still more than `mail.db.max_open` databases open, it closes the oldest ones until that number is reached.

I've changed this. The automatic clean up will now *not* close idle databases if they're larger than `mail.db.keep_open_size` bytes. To bring the number of open databases down it is now more likely to close *small* databases than ones that haven't been used lately. Thunderbird now also avoids closing large databases when switching folders.

Hopefully this will reduce the need to reopen large databases, which can take a long time. You can tune the preferences to suit your situation, at your own risk, of course. Also, you can get some logging info by changing `mailnews.database.dbcache.loglevel` to "All".