slog-async: even with increased chan_size, "logger dropped messages due to channel overflow"

slog-rs / async

Asynchronous drain for slog-rs v2

Apache License 2.0

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slog-async: even with increased chan_size, "logger dropped messages due to channel overflow" #26

Closed Geobert closed 3 years ago

Geobert commented 3 years ago

Hi,

I facing this "logger dropped messages due to channel overflow" when stress testing a server.

I've looked at how many records where dropped and increased the chan_size accordingly but I still have these drops, the biggest being hundred or so, so I increased again by adding more and more, but each time, I still have these drops of record :(

What am I doing wrong?

vorner commented 3 years ago

That sounds like you're logging more than what it can handle. The channel can only absorb a „burst“, not a sustained higher amount of messages. If you raise it, it'll sustain it for a bit longer, but eventually will run out anyway. You can choose between:

Slowing down the application by the logging (making it blocking).
Preferring performance over all the log messages and losing messages.

You could, in theory, set the channel size to insanely huge size so it absorbs the whole stress test, but that doesn't sound like a good idea in general.

Geobert commented 3 years ago

Thank you for your answer!

That's what I don't understand: I'm increasing the buffer like crazy and still got these drops.

I just want to do that for the stress test before setting a more reasonable size for the channel.

EDIT: after going up to 100k no drop anymore :D

EDIT2: It turns out I forgot to put a BufferWriter to my Drain, works way better with it… ^^'