fix: prevent blocking by running Loki client handle in goroutine

[danteu]

• When calling Client.Handle, the log entry is written to an unbuffered channel. This write blocks when the Loki client is trying to send a log batch to the Loki server. When the Loki server is unreachable, this can block for multiple minutes.
• This change fixes the issue by running Client.Handle in a separate goroutine.

Fixes #18

[samber]

Hi @danteu and thanks for your bug fix.

IMO, this fix is very dangerous, since it might leak an infinite number of goroutines.

I opened an issue in the client repository for a more reliable fix.

[danteu]

Hi @samber,

thanks for the review. While I agree that this fix is quite dirty and will lead to a significant number of goroutines in scenarios with many calls to Client.Handle, those goroutines will eventually terminate when sendBatch returns. But if you're logging aggressively, the number of idle goroutines would probably be unreasonable.

Thanks for opening the issue with the client library! It looks abandoned/unmaintained so I'm not very hopeful for a timely fix. :/

Best regards,
Daniel