limit parallel checking of torrents

[milahu]

currently there seems to be no limit, all torrents are checked in parallel

cpu load is about 25% when checking 20 torrents in parallel
so this is just slow, not causing too much cpu load

libtorrent has the setting hashing_threads

aka: limit number of checking threads

[ikatson]

There's probably a limit - the number of tokio IO worker threads. It's used for other things too though like writing to disk.
It's configurable from command line too: https://github.com/ikatson/rqbit/blob/main/crates/rqbit/src/main.rs#L105

Does that help?

[milahu]

tokio IO worker threads

too generic. hashing threads produce more CPU load

in this case, serial processing is better, because checked torrents are ready for seeding