Game saving/exit process hangs

[RitzScythe]

Made a modpack (Well Rounded Blockheads, in case the modlist on curseforge helps) and server to host it, worked fine until last night. The issue that pops up after some days being up/working is when you leave a world (singleplayer) or shutdown a server, the process hangs and jumps to 8.5gb ram used, eats up CPU usage (50-60% in taskman on a 3800x) and just sits there. If done on a single player world, the game doesnt fully crash, (e.g. if you alt+f4 buttons like save and quit, options stay in the window, are still clickable but they do nothing) Saving seems to still happen, as location/inventory updates if I restart server or client and play the world again.

 

If I start the currently afflicted server but dont login the server closes properly, its only once I log back in the problem occurs. Its a priv server and I dont have anyone else to test atm so Idk if its a prob with my player or players/area in general.

Only recent changes in game are the additions of a pnuematicraft pressure chamber, an enchanting table, and bookshelves from builders crafts and additions....

I've been trying to get help on this all day, so ANY assistance goes a long way, even if its a way to debug this myself >~<

Debug/Latest logs

[warjort]

Sounds like some code is looping during the server shutdown?

You can use a tool like jstack to get a thread dump to see where it is stuck.

https://www.baeldung.com/java-thread-dump

[RitzScythe]

Im a bit newbie at this, where/how do I use cmd line stuff like that? Link wasnt quite clear enough. Thanks in advance

[warjort]

Any command line your operating system provides should work as long as you have java on it's path.

NOTE: You need the jdk (java development kit) version of java instead of just the normal jre (java runtime environment).

[RitzScythe]

Okay got it going, so I'm assuming I reproduce issue, use jstack with the E arg for extended info while game is hanging?

[warjort]

You need to pass the process id of minecraft to the command.

Use the jps command or task manager to find it.

Edited November 30, 2022 by warjort

[RitzScythe]

Found the pid, tried to run jstack, told me to run jhsdb ran that, is giving some info in cmd, cant find a txt file output, not sure if it makes one or not, copied output to a txt file just in case. dunno if youd want to look at it, or provide info on where to learn to read it. Thanks again for the help thus far

[RitzScythe]

I see a mention of flywheel in the output, would that likely be the source of the issue?

[warjort]

If you want our help, you need to post the output of the command.

I believe windows has support for using pipes to redirect output to a file, something like?

jstack pid > output.txt

where pid is the process id.

Edited December 1, 2022 by warjort

[RitzScythe]

I did copy/past the log when I ran the cmd, I just didnt want to assume that was the kind of help offered. its the underscored word if that wasnt clear btw

Edited December 1, 2022 by RitzScythe

[warjort]

The client thread shows you in the pause screen.

The server thread shows hexerei responding to a chunk unload event for its Chest.

Quote

- net.minecraft.world.level.Level.m_46745_(net.minecraft.core.BlockPos) @bci=15, line=170 (Compiled frame)

- net.joefoxe.hexerei.tileentity.ModChestBlockEntity.lambda$sync$1() @bci=8, line=157 (Interpreted frame)

- net.joefoxe.hexerei.tileentity.ModChestBlockEntity$$Lambda$44384+0x0000000804333da8.get() @bci=4 (Interpreted frame)

- net.minecraftforge.network.PacketDistributor.lambda$trackingChunk$9(java.util.function.Supplier, net.minecraft.network.protocol.Packet) @bci=1, line=240 (Interpreted frame)

- net.minecraftforge.network.PacketDistributor$$Lambda$41836+0x0000000804027920.accept(java.lang.Object) @bci=8 (Interpreted frame)

- net.minecraftforge.network.PacketDistributor$PacketTarget.send(net.minecraft.network.protocol.Packet) @bci=5, line=165 (Compiled frame)

- net.minecraftforge.network.simple.SimpleChannel.send(net.minecraftforge.network.PacketDistributor$PacketTarget, java.lang.Object) @bci=10, line=107 (Compiled frame)

- net.joefoxe.hexerei.tileentity.ModChestBlockEntity.sync() @bci=54, line=157 (Interpreted frame)

- net.joefoxe.hexerei.tileentity.ModChestBlockEntity.onChunkUnloaded() @bci=1, line=151 (Interpreted frame)

It seems to be trying to broadcast a network packet to all players in the chunk.

 

Check to see if you still get the hang without this mod included.

[RitzScythe]

Yeah it actually went to the home screen, there are open issues related to chests and chunk loading, could it be related to that? Could destroying recently placed chests help?

[warjort]

You need to ask the mod author about their mod. 🙂 

[RitzScythe]

Alrighty, well the help was very much appreciated!