74 lines
4.0 KiB
Diff
74 lines
4.0 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Aikar <aikar@aikar.co>
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Date: Sat, 18 Apr 2020 04:36:11 -0400
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Subject: [PATCH] Fix Chunk Post Processing deadlock risk
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See: https://gist.github.com/aikar/dd22bbd2a3d78a2fd3d92e95e9f28dc6
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as part of post processing a chunk, we can call ChunkConverter.
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ChunkConverter then kicks off major physics updates, and when blocks
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that have connections across chunk boundaries occur, a recursive risk
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can occur where A updates a block that triggers a physics request.
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That physics request may trigger a chunk request, that then enqueues
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a task into the Mailbox ChunkTaskQueueSorter.
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If anything requests that same chunk that is in the middle of conversion,
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it's mailbox queue is going to be held up, so the subsequent chunk request
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will be unable to proceed.
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We delay post processing of Chunk.A() 1 "pass" by re stuffing it back into
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the executor so that the mailbox ChunkQueue is now considered empty.
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This successfully fixed a reoccurring and highly reproducible crash
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for heightmaps.
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diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
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index 7776c22744cdd31459e9634d1d549bdf2876e04f..43e5e148f1289ff5e42311981c597c66d98447aa 100644
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--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
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+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
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@@ -178,6 +178,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
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};
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// CraftBukkit end
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+ final CallbackExecutor chunkLoadConversionCallbackExecutor = new CallbackExecutor(); // Paper
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// Paper start - distance maps
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private final com.destroystokyo.paper.util.misc.PooledLinkedHashSets<ServerPlayer> pooledLinkedPlayerHashSets = new com.destroystokyo.paper.util.misc.PooledLinkedHashSets<>();
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@@ -995,16 +996,15 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
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});
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CompletableFuture<Either<LevelChunk, ChunkHolder.ChunkLoadingFailure>> completablefuture1 = completablefuture.thenApplyAsync((either) -> {
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return either.mapLeft((list) -> {
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- return (LevelChunk) list.get(list.size() / 2);
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- });
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- }, (runnable) -> {
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- this.mainThreadMailbox.tell(ChunkTaskPriorityQueueSorter.message(holder, runnable));
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- }).thenApplyAsync((either) -> {
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- return either.ifLeft((chunk) -> {
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+ // Paper start - revert 1.18.2 diff
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+ final LevelChunk chunk = (LevelChunk) list.get(list.size() / 2);
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chunk.postProcessGeneration();
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this.level.startTickingChunk(chunk);
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+ return chunk;
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});
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- }, this.mainThreadExecutor);
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+ }, (runnable) -> {
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+ this.mainThreadMailbox.tell(ChunkTaskPriorityQueueSorter.message(holder, () -> ChunkMap.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.
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+ }); // Paper end - revert 1.18.2 diff
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completablefuture1.thenAcceptAsync((either) -> {
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either.ifLeft((chunk) -> {
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diff --git a/src/main/java/net/minecraft/server/level/ServerChunkCache.java b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
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index 8f1609bbb5670d3b4acccb2cb4b9238ce13290bb..cf5a5d98420c3849621bfdfae7bda7d5cb4b2dc9 100644
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--- a/src/main/java/net/minecraft/server/level/ServerChunkCache.java
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+++ b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
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@@ -1133,6 +1133,7 @@ public class ServerChunkCache extends ChunkSource {
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return super.pollTask() || execChunkTask; // Paper
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}
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} finally {
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+ chunkMap.chunkLoadConversionCallbackExecutor.run(); // Paper - Add chunk load conversion callback executor to prevent deadlock due to recursion in the chunk task queue sorter
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chunkMap.callbackExecutor.run();
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}
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// CraftBukkit end
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