For some time my thunderbird occasionally emits quite annoying error message that another operation is in progress. It seems it is blocking itself. I have been running multiple thunderbird instances concurrently on _different_ machines. My home is local on encrypted disk, it is not shared in any way.

I have few folders configured to be compacted and dropped automatically. But this error happens in rows. It tells me for one folder, I click okay. It says another folder cannot be compacted too. Then it follows with 3-7 repeats, which are quite annoying.

Please help me finding a reason for this. I tried running thunderbird from terminal to see what it is writing. Unfortunately no error message were printed there.

Reproducible: Sometimes

Steps to Reproduce:
1. have thunderbird configured for gmail account
2. have a lot of mail folders for separate mailing lists
3. have it running few hours.
Actual Results:  
Quite annoying error message saying the operation could not be done.

Expected Results:  
Some kind of locking is done on each folder. Folder operations should have some jitter randomized, so they should not clash if I have multiple thunderbird instances connected to the same account.