PaperMC/Spigot-Server-Patches/0454-Fix-Chunk-Post-Processing-deadlock-risk.patch
Daniel Ennis c97ce029e9
1.16.2 Release (#4123)
PaperMC believes that 1.16.2 is now ready for general release as we fixed the main issue plagueing the 1.16.x release, the MapLike data conversion issues.

Until now, it was not safe for a server to convert a world to 1.16.2 without data conversion issues around villages and potentially other things. If you did, those MapLike errors meant something went wrong.

This is now resolved.

Big thanks to all those that helped, notably @BillyGalbreath and @Proximyst who did large parts of the update process with me.

Please as always, backup your worlds and test before updating to 1.16.2!

If you update to 1.16.2, there is no going back to an older build than this.

---------------------------------

Co-authored-by: William Blake Galbreath <Blake.Galbreath@GMail.com>
Co-authored-by: Mariell Hoversholm <proximyst@proximyst.com>
Co-authored-by: krolik-exe <69214078+krolik-exe@users.noreply.github.com>
Co-authored-by: BillyGalbreath <BillyGalbreath@users.noreply.github.com>
Co-authored-by: stonar96 <minecraft.stonar96@gmail.com>
Co-authored-by: Shane Freeder <theboyetronic@gmail.com>
Co-authored-by: Jason <jasonpenilla2@me.com>
Co-authored-by: kashike <kashike@vq.lc>
Co-authored-by: Aurora <21148213+aurorasmiles@users.noreply.github.com>
Co-authored-by: KennyTV <kennytv@t-online.de>
Co-authored-by: commandblockguy <commandblockguy1@gmail.com>
Co-authored-by: DigitalRegent <misterwener@gmail.com>
Co-authored-by: ishland <ishlandmc@yeah.net>
2020-08-24 22:40:19 -04:00

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3.3 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sat, 18 Apr 2020 04:36:11 -0400
Subject: [PATCH] Fix Chunk Post Processing deadlock risk
See: https://gist.github.com/aikar/dd22bbd2a3d78a2fd3d92e95e9f28dc6
as part of post processing a chunk, we can call ChunkConverter.
ChunkConverter then kicks off major physics updates, and when blocks
that have connections across chunk boundries occur, a recursive risk
can occur where A updates a block that triggers a physics request.
That physics request may trigger a chunk request, that then enqueues
a task into the Mailbox ChunkTaskQueueSorter.
If anything requests that same chunk that is in the middle of conversion,
it's mailbox queue is going to be held up, so the subsequent chunk request
will be unable to proceed.
We delay post processing of Chunk.A() 1 "pass" by re stuffing it back into
the executor so that the mailbox ChunkQueue is now considered empty.
This successfully fixed a reoccurring and highly reproduceable crash
for heightmaps.
diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
index 64190f8d80b22146796f71a14e166969ba175d0f..4c4e6e154e0db23662484d6aa03f1d762a48badb 100644
--- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
+++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
@@ -995,6 +995,7 @@ public class ChunkProviderServer extends IChunkProvider {
return super.executeNext() || execChunkTask; // Paper
}
} finally {
+ playerChunkMap.chunkLoadConversionCallbackExecutor.run(); // Paper - Add chunk load conversion callback executor to prevent deadlock due to recursion in the chunk task queue sorter
playerChunkMap.callbackExecutor.run();
}
// CraftBukkit end
diff --git a/src/main/java/net/minecraft/server/PlayerChunkMap.java b/src/main/java/net/minecraft/server/PlayerChunkMap.java
index 16e4acdb0f834883a480829a864ef7570035bc26..842f5ebad2a4d040b9912ec4841de426667cd91d 100644
--- a/src/main/java/net/minecraft/server/PlayerChunkMap.java
+++ b/src/main/java/net/minecraft/server/PlayerChunkMap.java
@@ -134,6 +134,8 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
};
// CraftBukkit end
+ final CallbackExecutor chunkLoadConversionCallbackExecutor = new CallbackExecutor(); // Paper
+
// Paper start - distance maps
private final com.destroystokyo.paper.util.misc.PooledLinkedHashSets<EntityPlayer> pooledLinkedPlayerHashSets = new com.destroystokyo.paper.util.misc.PooledLinkedHashSets<>();
@@ -999,7 +1001,7 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
return Either.left(chunk);
});
}, (runnable) -> {
- this.mailboxMain.a(ChunkTaskQueueSorter.a(playerchunk, runnable));
+ this.mailboxMain.a(ChunkTaskQueueSorter.a(playerchunk, () -> PlayerChunkMap.this.chunkLoadConversionCallbackExecutor.execute(runnable))); // Paper - delay running Chunk post processing until outside of the sorter to prevent a deadlock scenario when post processing causes another chunk request.
});
completablefuture1.thenAcceptAsync((either) -> {