Simul Host Lag Query

Hi there,

I was part of a simul which ran this evening. The host ended up losing a lot of games on time. We may have made some bad choices about the number of players and the time control, however it seemed to me that lag played a role. For each move played by the host there was a two or three second delay before they would see the next game, which multiplied across boards meant they lost significant amounts of time. Was this normal?

The event was live streamed, and a video of that is available here: www.youtube.com/watch?v=YgRrx5MGJO0, so you can check out the lag for yourself.

I'm speculating that the process of streaming itself contributed significantly to the lag, as the upload of the move would have been competing with the upload of the video/audio for the stream.

I'd be interested comments on this from the Lichess team (anything in your logs to explain?), but views from others with experience of Lichess simuls would also be welcome.

Thanks in advance.

Steve Lovell (iblunder)

It looks like a little big of lag from the stream itself (you can see the the videos of the two people on the upper right corner are laggy at times).

However, the lag of a couple seconds is caused by the amount of time it took for the device used to load the next game. In the video, you can see that right after a move was played, the browser indicates on the left side of the tab that the next game immediately starts to load, but it just takes a while to go to the next game. There probably wasn't any lag on the lichess servers. A little delay is inevitable when hosting simuls, but the delay was probably compounded by the stream taking a lot of the bandwidth, making the connection slower.

I wonder if someday github.com/Cqsi/lichs or similar will invent a board API client with faster board switching.

Thanks @Serial_Checkmater. I'll have a closer watch of the video myself.

I'm not especially thinking that the lichess servers caused the lag, I'm just after a diagnosis so we can do better if possible.

Do we think it's is the upload times that are the problem (bandwidth issues), or the redrawing of the screen itself (client side rendering slow due to large number of boards)?