Comment by avar | Hacker News Reader

Comment by avar | Hacker News Reader

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It doesn't matter how fast the index is, only one process can hold the Xapian lock, if I'm reading my E-Mail in Emacs with mu4e (which invokes "mu server") and try to index on the command-line I get:

    $ mu index [...]
    mu: mu_store_new_writable: xapian
    error 'Unable to get write lock on
    <Maildir>/xapian: already locked' (11)

How do you send E-Mail with no network connection? Last I checked this was some ad-hoc thing where you neede dto queue them up in some queue managed by Emacs, and remember to turn that mode off when you were back on WiFi (or hack up your own hooks to automate this), v.s. sending it to a local smtpd which already has retry logic built-in.

Why on earth would I try and index it twice concurrently?

I never have a scenario where I need to send email without network.

No, you wouldn't index from two processes concurrently, but for Emacs to read your mail in mu4e and for you to concurrently issue "mu index" on the command-line two processes ("mu server" and "mu index") would need to poen the same Xapian database read-write at the same time, and just like SQLite Xapian doesn't support that.

... I still don't see why I would do that. Emacs runs offlineimap and then Emacs runs mu index. Why would I do it again myself from the command line?

Yeah I use notmuch with Emacs and it's the same. If you try to search, refresh search results, or read email while the index process is running you get an error. It's not a big deal for me, because I download and index my mail from the command line, so I'll never be reading or sending email at the same time.

This used to be true but notmuch has added support for Xapian's DB_RETRY_LOCK feature a couple of years ago so if you have non-ancient notmuch (0.23+) and Xapian (1.3.2+) then the second process will wait for the lock instead of erroring out. The feature can be disabled at compile time if you don't want it for some reason.

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