60 lines
3.3 KiB
Diff
60 lines
3.3 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 boundries 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 reproduceable 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 6d810cdb538d078dbf7ccd2ef84a4be27eb1f3e7..aa9846c7d6b8499e01bf0ffeece6a940e0879328 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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@@ -195,6 +195,7 @@ 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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// Paper start - no-tick view distance
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@@ -1091,7 +1092,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
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return Either.left(chunk);
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});
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}, (runnable) -> {
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- this.mainThreadMailbox.tell(ChunkTaskPriorityQueueSorter.message(holder, 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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});
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completablefuture1.thenAcceptAsync((either) -> {
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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 7cc8a898b5a6349da91b34b8be6ec00707183589..3e7469032d38b9432bb36d37214524ca2df11098 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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@@ -1014,6 +1014,7 @@ 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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