Factorio Forums

Hi
Can you please help debug my issue? It might be connected to about 20k of logistic robots, not sure

Can you tell me if attached info is enough to determine what is causing the lag?

i am adding more information:
- another screenshoot:
- log file: https://www.dropbox.com/scl/fi/8v3n2ahv ... w4sxl&dl=0
- save: https://www.dropbox.com/scl/fi/8wdlunyk ... nhq3u&dl=0

Does the issue persist when running the save in single player?

Just checked, in single player I have both UPS and FPS at 46

Post the screenshot and log of that session. And post a server log if you have access to it.

sure, here are:
- single player screenshoot
- single player log: https://www.dropbox.com/scl/fi/psk87utx ... q99nw&dl=0
- multiplayer - server - log: https://www.dropbox.com/scl/fi/8v3n2ahv ... q9w6e&dl=0

I believe this is just the server performance being the limiting factor and the save file going beyond what it can handle. I would not have expected the server to be that much slower than the client hardware though, so I'd check the servers cpu temperature.

fan1: 3400 RPM
fan2: 3400 RPM
CPU: +72.0°C
GPU: +59.0°C
temp3: +53.0°C
temp4: +0.0°C
temp5: +0.0°C
temp6: +0.0°C
temp7: +0.0°C
temp8: N/A

do you believe that server cpu might be a limiting factor of client fps? it is little surprising to me
server ups is even higher than client ups

server load is 2-3 per 8 cores, which is not even 50%

orestlenczyk wrote: Wed Apr 16, 2025 9:44 pm do you believe that server cpu might be a limiting factor of client fps? it is little surprising to me
server ups is even higher than client ups

server load is 2-3 per 8 cores, which is not even 50%

Yes, the frame time is just high because it's waiting for the update which comes from the server. Try running the save in single player on the server machine if that is possible and post a screenshot of that.

Loewchen wrote: Wed Apr 16, 2025 9:10 pm I believe this is just the server performance being the limiting factor

The opposite, rather: this seems like a classic case of "you can barely keep up with the server so your computer is dropping frames to make sure the simulation doesn't fall behind."

Jap2.0 wrote: Wed Apr 16, 2025 10:33 pm The opposite, rather: this seems like a classic case of "you can barely keep up with the server so your computer is dropping frames to make sure the simulation doesn't fall behind."

Not based on the screenshots, the client is ahead in updates, does not jump any frames and latency is in the single digits. Op could try to slow down the server though just to rule out a really unlucky screenshot timing.

Loewchen wrote: Wed Apr 16, 2025 10:51 pm Not based on the screenshots, the client is ahead in updates, does not jump any frames and latency is in the single digits. Op could try to slow down the server though just to rule out a really unlucky screenshot timing.

Oh there's a thing where if the server is running <60 UPS and the client can keep up the client displays 60 UPS instead of the actual speed the server is running at, isn't there.

You might be right, something isn't adding up in my head but I can't quite place it.

On a laptop with a CPU very similar to the server (slightly weaker) I get about 40 FPS/UPS (30 when on battery).

so you are telling me, that server is a bottleneck? So why factorio is not utilizing whole cpu?


> Try running the save in single player on the server machine if that is possible and post a screenshot of that.
Unfortunately that would not be possible, server does not have a gui, it is running headless factorio only

orestlenczyk wrote: Thu Apr 17, 2025 7:24 am Unfortunately that would not be possible, server does not have a gui, it is running headless factorio only

Yes, you would have to install the normal version on it.

Alternatively check if the low fps issue persist if you run the game at half speed with the command: /c game.speed = 0.5

Actually I was able to narrow down the issue to 250k idle logistic bots on Fulgora. 20k of them were waiting for free roboport slots. After placing them in storage chests, FPS/UPS is 60/60 again.

But I still have doubts, how server can be the bottleneck, if load was never higher than 3 per 8 cores

orestlenczyk wrote: Thu Apr 17, 2025 12:58 pm Actually I was able to narrow down the issue to 250k idle logistic bots on Fulgora. 20k of them were waiting for free roboport slots. After placing them in storage chests, FPS/UPS is 60/60 again.

But I still have doubts, how server can be the bottleneck, if load was never higher than 3 per 8 cores

CPU core count usage is 1 part of the entire computers ability to run programs. It's simply an easy number for the operating system to show compared to everything else that it's doing.

What other factors would you consider? I am working in IT for 15 years, and that would be my first case where server CPU is bottleneck and underutilized at the same time

Loewchen wrote: Thu Apr 17, 2025 10:54 am

orestlenczyk wrote: Thu Apr 17, 2025 7:24 am Unfortunately that would not be possible, server does not have a gui, it is running headless factorio only

Yes, you would have to install the normal version on it.

Alternatively check if the low fps issue persist if you run the game at half speed with the command: /c game.speed = 0.5

I have speed up the game to 2.0. FPS/UPS were 10/100, and the cpu usage 80% on main thread, and just 10% on other threads

orestlenczyk wrote: Thu Apr 17, 2025 1:44 pm What other factors would you consider? I am working in IT for 15 years, and that would be my first case where server CPU is bottleneck and underutilized at the same time

Parts of Factorio are bound by a single thread, parts are bound by memory latency and/or throughout.