Paper/Spigot-Server-Patches/0481-Fix-Chunk-Post-Processing-deadlock-risk.patch
Aikar b6cf80ee66
Preload important classes such as Logger and JLine
This is for 2 reasons:
1) Ensuring our log4j is mostly loaded at OUR version.
   I've seen stack traces with line numbers that do not match our version. This means that some
   plugin has shaded in log4j and their loaded version is mixing with ours....
   So by at least trying to load a bunch of log4j classes before we load plugins, we can be
   more sure mixed versions are not loading.

2) If the jar file is replaced while the server is runnimg class not found errors galore
   This will preloaod a bunch of classes commonly seen to error during shutdown due to this.

   The goal here is to help let the server shutdown gracefully as possible. Some plugins will
   still blow up here if they access a class that hadn't been loaded yet, but goal is to at least
   stop freezing the shutdown process as it does with JLine and Log4j errors requiring an external kill.

   Ideally you should not replace jars while the server is running, but it is something that happens in
   development for testing.

Updated test server to do a copy though to avoid this happening in Paper development.
2020-05-24 13:19:08 -04:00

61 lines
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 722db939971fe395d8250c388fbd7f3b5e87804d..ba99e9949c6fdfc4f49b6b6716100eb51697227d 100644
--- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
+++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
@@ -1040,6 +1040,7 @@ 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 485e5d2778064c64c8dc8375b18c785649049184..a9f6c0835c3ae37b12d6b8b7ea59ccba7651a82a 100644
--- a/src/main/java/net/minecraft/server/PlayerChunkMap.java
+++ b/src/main/java/net/minecraft/server/PlayerChunkMap.java
@@ -131,6 +131,8 @@ 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<>();
@@ -986,7 +988,7 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
return Either.left(chunk);
});
}, (runnable) -> {
- this.mailboxMain.a(ChunkTaskQueueSorter.a(playerchunk, runnable)); // CraftBukkit - decompile error
+ this.mailboxMain.a(ChunkTaskQueueSorter.a(playerchunk, () -> PlayerChunkMap.this.chunkLoadConversionCallbackExecutor.execute(runnable))); // CraftBukkit - decompile error // 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) -> {