Problem Sudden increase of memory usage

[vince959]

I am running a MindCrack server with no other mod or plugins. Starting like a few hours ago, the memory usage of server jumped from normally 2k Gb to now nearly 6k Gb and is causing a huge amount of block lag and delays.
Some players reported that they cant even get the chest opened (they were fine before this) but while some players are able to play smoothly. Tried restarting the server and even rebooted the machine but it didnt help at all.

I do not see anything weird going on on the server log beside the common "can't keep up" message. Any hint where I can start looking for problems?

Edit: noticed there is a message in log like this [STDOUT]Null Grid... i dont think this is an error but what makes this message appear?

 

[Francis Baster]

It sounds like there might be an excessive amount of item entities in someones base from a pipe overflow. If someone is suffering a large fps drop, they might be near to the overflow. NEI's magnet mode and delete button are useful for item cleanups. It might be worth installing the aPerf mod, as this gives you detailed information on the amount of currently loaded entities and lets you remove dropped items from all loaded chunks.

 

[Dingham]

Above definitely.

Also worth checking world anchors...etc. People might be using a lot of them now which will increase memory and CPU load.

 

[DZCreeper]

This sounds. . . bad.

Not even quarrying an area and making it all flowing water should create that much lag. My idea is that someone made a system that can hold infinite items using weird mod mechanics. They feed it tons of items, and it either lagged out from items, or it broke and all the items spilled.