Direwolf20 periodic "Server Behind, skipping ticks"

GreenZombie

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Jul 29, 2019
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A direwolf20 server I (now) admin has a chronic problem with reporting, at least every minute, that it is (on average) ~4000ms behind, and it is skipping ~200ticks.

This is annoying as it manifests as periodic block lag for players, prevents interaction with chests, etc. Being server lag, at least it doesn't result in teleporting monsters and death.

Having spent 4 days tracking down player chunk loaders, mass use of open block tanks and other (obvious) souces of bad server performance I have the server using a lot less memory, and with a relatively solid 25ms frame time - but still the log fills with "Server is behind" messages, EVERY MINUTE.

On a whim I fired up a local instance of the server on my own PC, but as I could not wait for the ~6GB of map to download I started it with an empty save folder. I ran opis to get a comparative performance, and blow me down but on a completely fresh install of the server, with ONLY the spawn chunks loaded and no player built stuff at all, I get the same periodic "Server is behind" message - every minute.

WTF. Any ideas which mod is causing this?
 

GreenZombie

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Jul 29, 2019
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The chronic periodic frame skipping was manifest on a out-the-box direwolf20 install. We have subsequently installed Forge Essentials, but other than making the server awesome to administer, has not changed the periodic lag.
 
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Dahc

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Jul 29, 2019
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It strikes me that my problem could be garbage collection and / or the incorrect JVM parameters.

What are the recommended JVM parameters for FTB packs?
--
http://forum.feed-the-beast.com/threads/jvm-arguments-for-modded-minecraft-updated-12-30-13.28994/
is 2 years old, and lists parameters relevant to Java 1.7, not Java 1.8 :/
I, too, would like to know this. I own an Infinity Evolved server, and my params put me on the edge of lag free play, and minorly annoying lag. Sometimes I can get lag free, but only if the internet connection has no slow down on both ends.