Need to close() and possibly pool hypercore instances

[pfrazee]

AFAICT, via random-access-file, hypercore opens a file-descriptor for every instance, and doesn't close the FD until .close() is called. We definitely don't want to leak those.

Any time hypercore-archiver's get() method is called (eg in archiver-api's archiveProgress() method) a hypercore instance is created. Thus, another FD is created, and not cleaned up.

Two thoughts on that:

1. We need to be sure to clean up all hypercores by .close()ing them
2. Should we be pooling hypercore instances instead of creating them with .get() every time?

[pfrazee]

Alternatively, we could pool random-access-file instances, but in either case we'll still need to .close the hypercores

[pfrazee]

Archiver-server has a solution we can consider: an LRU cache.

[joehand]

Should we be pooling hypercore instances instead of creating them with .get() every time?

Ya, we could definitely optimize the get to not create them every time. Seems like a LRU cache would be the most straightforward way to implement that.