Netty error on server

[Matt Calder]

Title Netty error on server

Launcher Type Twitch Desktop App

Modpack Direwolf20

Modpack version 1.1.0

Have you modified the pack? Yes

Link to log file http://paste.feed-the-beast.com/view/298db271

Details of the issue - Added several mods including mekanism, mekanismgenerators, woot, and updated extrautils to a new version.

Got a netty error indicating a possible memory leak and console message given was "INFO SEVERE: LEAK: ByteBuf.release() was not called before it's garbage-collected. Enable advanced leak reporting to find out where the leak occurred. To enable advanced leak reporting, specify the JVM option '-Dio.netty.leakDetection.level=advanced' or call ResourceLeakDetector.setLevel()"

After enabling advanced leak detection the log that is linked was given.

I am also running VisualVM to monitor the CPU usage of the server and noticed that netty was using a fair chunk of CPU (screenshot included).

Also people sometimes disconnect with the error included in the pastebin.

https://imgur.com/a/a9x0o

 

[grandrolf]

Antivirus software or other security software running on the server host?

 

[Matt Calder]

Antivirus software or other security software running on the server host?

Disabled 3rd party antivirus, only windows defender running and the firewall is disabled.

Issue only started appearing after a number of weeks of the server running, so it wasn't occurring even when antivirus was enabled.

 

[Henry Link]

So as a test can you rename the world folder and see if the server will generate a new world and see if you can connect to that?

 

[Matt Calder]

So as a test can you rename the world folder and see if the server will generate a new world and see if you can connect to that?

Myself and others have no trouble connecting, however after a short while of the server being online the error messages that I linked to appear and then the server starts to experience noticeable lag (1-2 secs to open inventories etc).
The disconnect message occurs only occasionally, but again seems to occur more often after the server has been running for a while.

 

[Henry Link]

So, is this a dedicated server machine? Also, have you customized the startup scripts to reduced the garbage collector pause? How much RAM are you allocating to the server? Are you getting any "Server can't keep up messages" in the console? Lastly, did you even try the test with a new world? I'm just asking for a test. I'm not asking for you to give up on your old world.

One last thing if you have the hardware for it. Have you considered moving your server to a linux OS?

 

[Matt Calder]

So, is this a dedicated server machine? Also, have you customized the startup scripts to reduced the garbage collector pause? How much RAM are you allocating to the server? Are you getting any "Server can't keep up messages" in the console? Lastly, did you even try the test with a new world? I'm just asking for a test. I'm not asking for you to give up on your old world.

One last thing if you have the hardware for it. Have you considered moving your server to a linux OS?

It is a spare PC that I am using solely to run the server.
I haven't really touched the startup scripts other than to increase allocated ram (which is currently set to 6GB). I'll try reducing the garbage collector pause if I can find out how.
I usually get one "can't keep up message" right after the server is finished loading, apart from that I haven't noticed anymore, although there may have been the occasional one when I wasn't checking the console.
I'll try the test with a new world tomorrow or the next day.

Hadn't considered moving to Linux, not sure what the hardware requirements are like and also what OS to use.

 

[Henry Link]

I run Ubuntu 16.04 on mine. It can be a little difficult to learn though. Since there is no graphical environment and everything is done via SSH command line and SFTP (file transfer). But, it runs minecraft a lot smoother since there is no overhead of maintaining a graphical environment or other Microsoft services which really aren't needed on a minecraft server.

 

[grandrolf]

Disabled 3rd party antivirus

If you have 3rd party antivirus installed on the machine - you need to remove it completely or add exceptions, just disable will not always do the trick.

 

[Matt Calder]

If you have 3rd party antivirus installed on the machine - you need to remove it completely or add exceptions, just disable will not always do the trick.

Sorry, what I meant was uninstalled. The antivirus was completely removed, I just worded it badly.

 

[grandrolf]

Move the server to a different machine temporarily - that way you know if the issue is with the machine or the MC-server/world.

If it's the machine, make sure all drivers are up to date (go to vendor and download the latest ones).

Is it a old machine (share a dxdiag from the machine, that will show specifications - use paste.feed-the-beast.com)