Deadlock when using thruster and CC

[alesharik]

In overworld, I have setup with thrusters and CC computer reading stats from them. When I go into nether, and go back - server thread blocks and I cannot continue playing in overworld.

It could be a bug in CC itself (seems like cc-tweaked/CC-Tweaked#2450 have same root case). But maybe if setControlMode is deferred to server thread, deadlock will be resolved.

Relevant stack-trace:

"ComputerCraft-Computer-Worker-0" #218 [152917] daemon prio=3 os_prio=0 cpu=570,37ms elapsed=104,71s tid=0x00007f7884764a20 nid=152917 waiting on condition  [0x00007f78dedfc000]
   java.lang.Thread.State: WAITING (parking)
	at jdk.internal.misc.Unsafe.park(java.base@21.0.7/Native Method)
	- parking to wait for  <0x00000012bcd30720> (a java.util.concurrent.CompletableFuture$Signaller)
	at java.util.concurrent.locks.LockSupport.park(java.base@21.0.7/LockSupport.java:221)
	at java.util.concurrent.CompletableFuture$Signaller.block(java.base@21.0.7/CompletableFuture.java:1864)
	at java.util.concurrent.ForkJoinPool.unmanagedBlock(java.base@21.0.7/ForkJoinPool.java:3780)
	at java.util.concurrent.ForkJoinPool.managedBlock(java.base@21.0.7/ForkJoinPool.java:3725)
	at java.util.concurrent.CompletableFuture.waitingGet(java.base@21.0.7/CompletableFuture.java:1898)
	at java.util.concurrent.CompletableFuture.join(java.base@21.0.7/CompletableFuture.java:2117)
	at net.minecraft.server.level.ServerChunkCache.getChunk(minecraft@1.21.1/ServerChunkCache.java:138)
	at net.minecraft.world.level.Level.getChunk(minecraft@1.21.1/Level.java:202)
	at net.minecraft.world.level.LevelReader.getChunk(minecraft@1.21.1/LevelReader.java:130)
	at net.minecraft.world.level.Level.getChunk(minecraft@1.21.1/Level.java:196)
	at net.minecraft.world.level.Level.getChunkAt(minecraft@1.21.1/Level.java:192)
	at net.minecraft.world.level.Level.blockEntityChanged(minecraft@1.21.1/Level.java:943)
	at net.minecraft.world.level.block.entity.BlockEntity.setChanged(minecraft@1.21.1/BlockEntity.java:198)
	at net.minecraft.world.level.block.entity.BlockEntity.setChanged(minecraft@1.21.1/BlockEntity.java:193)
	at com.simibubi.create.foundation.blockEntity.SyncedBlockEntity.notifyUpdate(create@6.0.10/SyncedBlockEntity.java:65)
	at dev.propulsionteam.propulsionsimulated.content.thruster.AbstractThrusterBlockEntity.setControlMode(createpropulsion@1.1.4/AbstractThrusterBlockEntity.java:141)
	at dev.propulsionteam.propulsionsimulated.compat.computercraft.ThrusterPeripheral.attach(createpropulsion@1.1.4/ThrusterPeripheral.java:128)
	at dan200.computercraft.shared.peripheral.modem.wired.WiredModemPeripheral$RemotePeripheralWrapper.attach(computercraft@1.119.0/WiredModemPeripheral.java:336)
	at dan200.computercraft.shared.peripheral.modem.wired.WiredModemPeripheral.attachPeripheralImpl(computercraft@1.119.0/WiredModemPeripheral.java:293)
	at dan200.computercraft.shared.peripheral.modem.wired.WiredModemPeripheral.attach(computercraft@1.119.0/WiredModemPeripheral.java:235)
	- locked <0x00000012bdd30720> (a java.util.HashMap)
	at dan200.computercraft.core.apis.PeripheralAPI$PeripheralWrapper.attach(computercraft@1.119.0/PeripheralAPI.java:74)
	- locked <0x00000012bcd30938> (a dan200.computercraft.core.apis.PeripheralAPI$PeripheralWrapper)
	at dan200.computercraft.core.apis.PeripheralAPI.startup(computercraft@1.119.0/PeripheralAPI.java:241)
	- locked <0x00000012bcd30a38> (a [Ldan200.computercraft.core.apis.PeripheralAPI$PeripheralWrapper;)
	at dan200.computercraft.core.computer.ApiWrapper.startup(computercraft@1.119.0/ApiWrapper.java:19)
	at dan200.computercraft.core.computer.ComputerExecutor.turnOn(computercraft@1.119.0/ComputerExecutor.java:401)
	at dan200.computercraft.core.computer.ComputerExecutor.workImpl(computercraft@1.119.0/ComputerExecutor.java:491)
	at dan200.computercraft.core.computer.ComputerExecutor.work(computercraft@1.119.0/ComputerExecutor.java:460)
	at dan200.computercraft.core.computer.computerthread.ComputerThread$WorkerThread.runImpl(computercraft@1.119.0/ComputerThread.java:639)
	at dan200.computercraft.core.computer.computerthread.ComputerThread$WorkerThread.run(computercraft@1.119.0/ComputerThread.java:593)
	at java.lang.Thread.runWith(java.base@21.0.7/Thread.java:1596)
	at java.lang.Thread.run(java.base@21.0.7/Thread.java:1583)

"Server thread" #202 [152806] prio=8 os_prio=0 cpu=30628,72ms elapsed=128,03s tid=0x00007f793dfb57a0 nid=152806 waiting for monitor entry  [0x00007f78d0d7d000]
   java.lang.Thread.State: BLOCKED (on object monitor)
	at dan200.computercraft.shared.peripheral.modem.wired.WiredModemElement.networkChanged(computercraft@1.119.0/WiredModemElement.java:33)
	- waiting to lock <0x00000012bdd30720> (a java.util.HashMap)
	at dan200.computercraft.impl.network.wired.WiredNetworkChangeImpl.broadcast(computercraft@1.119.0/WiredNetworkChangeImpl.java:85)
	at dan200.computercraft.impl.network.wired.WiredNetworkImpl.updatePeripherals(computercraft@1.119.0/WiredNetworkImpl.java:335)
	at dan200.computercraft.impl.network.wired.WiredNodeImpl.updatePeripherals(computercraft@1.119.0/WiredNodeImpl.java:60)
	at dan200.computercraft.shared.peripheral.modem.wired.CableBlockEntity.updateConnectedPeripherals(computercraft@1.119.0/CableBlockEntity.java:229)
	at dan200.computercraft.shared.peripheral.modem.wired.CableBlockEntity.attachPeripheral(computercraft@1.119.0/CableBlockEntity.java:219)
	at dan200.computercraft.shared.peripheral.modem.wired.CableBlockEntity.blockTick(computercraft@1.119.0/CableBlockEntity.java:176)
	at dan200.computercraft.shared.peripheral.modem.wired.CableBlock.tick(computercraft@1.119.0/CableBlock.java:257)
	at net.minecraft.world.level.block.state.BlockBehaviour$BlockStateBase.tick(minecraft@1.21.1/BlockBehaviour.java:732)
	at net.minecraft.server.level.ServerLevel.tickBlock(minecraft@1.21.1/ServerLevel.java:762)
	at net.minecraft.server.level.ServerLevel$$Lambda/0x0000000085d24e98.accept(minecraft@1.21.1/Unknown Source)
	at net.minecraft.world.ticks.LevelTicks.runCollectedTicks(minecraft@1.21.1/LevelTicks.java:215)
	at net.minecraft.world.ticks.LevelTicks.tick(minecraft@1.21.1/LevelTicks.java:98)
	at net.minecraft.server.level.ServerLevel.tick(minecraft@1.21.1/ServerLevel.java:367)
	at net.minecraft.server.MinecraftServer.tickChildren(minecraft@1.21.1/MinecraftServer.java:1037)
	at net.minecraft.server.MinecraftServer.tickServer(minecraft@1.21.1/MinecraftServer.java:917)
	at net.minecraft.client.server.IntegratedServer.tickServer(minecraft@1.21.1/IntegratedServer.java:110)
	at net.minecraft.server.MinecraftServer.runServer(minecraft@1.21.1/MinecraftServer.java:707)
	at net.minecraft.server.MinecraftServer.lambda$spin$2(minecraft@1.21.1/MinecraftServer.java:267)
	at net.minecraft.server.MinecraftServer$$Lambda/0x0000000085b59588.run(minecraft@1.21.1/Unknown Source)
	at java.lang.Thread.runWith(java.base@21.0.7/Thread.java:1596)
	at java.lang.Thread.run(java.base@21.0.7/Thread.java:1583)

[KyivSec]

Would be better to attach the whole log instead of just the stack trace

[alesharik]

My bad, this is not real stack-trace, this is JVM thread dump.
I checked logs when analysing the problem, and there are nothing of interest in these - just CC messages about timeouts.

But, anyway, with fix from my PR deadlock did not occur for ~15 hours of playing. So, seems like issue can be closed after a new release with changes.