43 lines
2.0 KiB
Diff
43 lines
2.0 KiB
Diff
From 0ad488560e10639c5fb359999c8b16487780fd21 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/PlayerChunkMap.java b/src/main/java/net/minecraft/server/PlayerChunkMap.java
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index c38d31faf..12639dfb9 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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@@ -1002,7 +1002,7 @@ 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)); // CraftBukkit - decompile error
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+ this.mailboxMain.a(ChunkTaskQueueSorter.a(playerchunk, () -> this.executor.addTask(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.
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});
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completablefuture1.thenAcceptAsync((either) -> {
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--
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2.25.1
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