Problem

When the process gets restarted it tries to load 1000 files by default and it tries to load them concurrently and it introduces errors (Too many open files (os error 24)) on platforms that have lower default for number of file handles than 1000. For example on macos, looks like it is set to 256 by default.

Solution

To enable users to load the files without having to change the default number of file descriptors for the platform, it'd be a better experience for the user to control the number of files that can be loaded concurrently. The CLI flag could be --load-snapshots-concurrency-limit (which is in line with the --wal-replay-concurrency-limit that limits number of WAL files that can be loaded concurrently).

Additional Context

This issue has been described by Dean in this slack thread