Profiling a remote server

[matejdro]

On our server we have some serious lag spike issues. TPS can be 20 and then randomly drop to around 5 and stay there for few minutes (or seconds) and then again go up etc. But eventually it will drop and then stay at very low number (around 3-4) until server restart.

Spilled items are not problem (NoLagg always reports around 15 or less dropped items and //remove items -1 does not help with the lag).

We want to profile a server with something like VisualVM to figure out which mod exactly is causing so much lag, but problem is that VisualVM does not support remote profiling and server is linux console so running VisualVM on server itself is not an option.

Is there any other way to profile server and figure out which classes use most CPU?

[matejdro]

Weird, I had all players but me disconnected and then I went to the edge of the map where there are no machines or anything around (just an ocean) and tickrate was still around 2.

World Anchors and Teleport Tethers are disabled and Dimensional anchor removed, so nothing was loaded except chunk I was standing in (and spawn of course, but I doubt there is anything at spawn that could drop tickrate so severely).

That means that lag is created by server itself? Any ideas what could be causing such drastic lag?

[Diabloz]

I have lag down to a science on my tekkit server, The problem with TPS lagg issues comes from many sources.

Here is a list on confirmed (based on my tests TPS) affecting things that will lag your server:

Wireless red stone - (i haven't found why, just it costs 3-5 TPS to run)

Quarries - (the bigger the laggier your server will be will usually after 1-15 TPS major Source of server Lag)

Buildcraft pipes - Laggy when having a large amount of items running through them (about 1-5 TPS)

IC2 machines and Power converters- will cost about 2TPS Max, will cause more client side lag rather

Terrible wiring- will cause some lag, usually 1-7 TPS on loaded chunks.

Computer craft Loops - Any os.reboot loop will cause about 1-18TPS server lag (can bring a server to its knees)

mob Entities - depends on number of players

Loaded chunks - depends on number of players and anchors

Error spams on consoles - Obvious don't ignore these.

Red power clocks/timers/cobble stone generators - varies

Large amount of plugin - these can have major impact, especially if they are poorly configured.

Tips:

under the buildcraft config setting there is a network manager setting increase the value to remove most of BC lagg, though quarries will still have major impact on server TPS

find a plugin that will Cap number of entities on your map

I created a linux script that will remove os.reboot loops

My Map moderates fix or remove laggy wiring/factories

Seriously think in removing plugins/mods your really don't need.

[matejdro]

Thanks for your post!

We made some modifications and right now it appears to be running OK. But this is no indication, because lag spikes can come at random :(