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4768e3c4ed
Reduces number of instructions a chunk lookup does when accessing the last chunk cache. This reduces amount of work and opcodes and allows better inlining. In lots of profiling comparisons, this optimization was able to reduce the cost of repeated chunk lookups that hit the cache pretty significantly.
61 lines
3.3 KiB
Diff
61 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/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
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index 106a0e3b7bf3ee563b45a67db25a07114da2cf42..f7355ca6d75c783b663b027efc2ccf6c07e6191d 100644
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--- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
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+++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
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@@ -986,6 +986,7 @@ public class ChunkProviderServer extends IChunkProvider {
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return super.executeNext() || execChunkTask; // Paper
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}
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} finally {
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+ playerChunkMap.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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playerChunkMap.callbackExecutor.run();
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}
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// CraftBukkit end
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diff --git a/src/main/java/net/minecraft/server/PlayerChunkMap.java b/src/main/java/net/minecraft/server/PlayerChunkMap.java
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index 1b5c97c74b7224a8ac4d6e834925c0509a57d308..33e0a93917e67860704e08e639cca1dbdf3b2708 100644
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--- a/src/main/java/net/minecraft/server/PlayerChunkMap.java
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+++ b/src/main/java/net/minecraft/server/PlayerChunkMap.java
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@@ -134,6 +134,8 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
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};
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// CraftBukkit end
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+ final CallbackExecutor chunkLoadConversionCallbackExecutor = new CallbackExecutor(); // Paper
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+
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// Paper start - distance maps
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private final com.destroystokyo.paper.util.misc.PooledLinkedHashSets<EntityPlayer> pooledLinkedPlayerHashSets = new com.destroystokyo.paper.util.misc.PooledLinkedHashSets<>();
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@@ -999,7 +1001,7 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
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return Either.left(chunk);
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});
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}, (runnable) -> {
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- this.mailboxMain.a(ChunkTaskQueueSorter.a(playerchunk, runnable));
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+ 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.
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});
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completablefuture1.thenAcceptAsync((either) -> {
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