Because in CliClient.resume() we don't account for the case, when there is an exception in one of the async processing stages:

void resume() {
	...
	try {
		client.startAsync(state -> {
			printer.ifPresent(p -> p.print(state));
			if (!options.shouldSeedAfterDownloaded() && state.getPiecesRemaining() == 0) {
				runtime.shutdown();
			}
		}, 1000); // <-- CompletableFuture.w

I discovered that verifying hashes with -c is much slower than generating them.

I was using this command:

rhash -c --skip-ok download.sfv

iotop reported disk read speeds of 30 MB/sec and rhash was consuming 100% CPU.

Then I thought, how does rhash know that the SFV file contains MD5 hashes? It probably doesn't, and it runs all checksum algorithms when doing a check and see

Now I use a SQL to cleanup torrents belongs to nobody.

DELETE
FROM torrents
WHERE id NOT IN (
  SELECT torrent_id
  FROM user_torrents
)

This should be done automatically.