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Fix FileIOThread concurrency issues (fixes #1505)

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FileIOThread was using two volatile counters in order to track if
any pending work was in the queue, this causes potential concurrency
issues when this counter is updated from multiple threads, potentially
causing these counters to desync due to the unsafe volatile update
This commit is contained in:
Shane Freeder 2018-10-03 19:07:08 +01:00
parent a64b0952cb
commit 26153def87
1 changed files with 35 additions and 0 deletions
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Spigot-Server-Patches/0386-Fix-FileIOThread-concurrency-issues.patch Normal file
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@ -0,0 +1,35 @@
From c829c08588842173ed4ce8d43a61f25e2a6a848c Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Wed, 3 Oct 2018 19:04:53 +0100
Subject: [PATCH] Fix FileIOThread concurrency issues
FileIOThread was using two volatile counters in order to track if
any pending work was in the queue, this causes potential concurrency
issues when this counter is updated from multiple threads, potentially
causing these counters to desync due to the unsafe volatile update
diff --git a/src/main/java/net/minecraft/server/FileIOThread.java b/src/main/java/net/minecraft/server/FileIOThread.java
index 97917551..1959bc06 100644
--- a/src/main/java/net/minecraft/server/FileIOThread.java
+++ b/src/main/java/net/minecraft/server/FileIOThread.java
@@ -9,7 +9,7 @@ import org.apache.logging.log4j.Logger;
public class FileIOThread implements Runnable {
private static final Logger a = LogManager.getLogger();
private static final FileIOThread b = new FileIOThread();
- private final List<IAsyncChunkSaver> c = Collections.synchronizedList(Lists.newArrayList());
+ private final List<IAsyncChunkSaver> c = Collections.synchronizedList(Lists.newArrayList()); private List<IAsyncChunkSaver> getThreadedIOQueue() { return c; } // Paper - OBFHELPER
private volatile long d;
private volatile long e;
private volatile boolean f;
@@ -72,7 +72,7 @@ public class FileIOThread implements Runnable {
public void b() throws InterruptedException {
this.f = true;
- while(this.d != this.e) {
+ while(!this.getThreadedIOQueue().isEmpty()) { // Paper - check actual list size
Thread.sleep(10L);
}
--
2.19.0