PaperMC/Spigot-Server-Patches/0308-Optimize-Region-File-Cache.patch
Aikar 835bc39b03
Paper 1.13.1 Update
Updated Upstream (Bukkit/CraftBukkit/Spigot)

Bukkit Changes:
2dcc44dc SPIGOT-4307: Fix hacky API for banners on shields
e0fc6572 SPIGOT-4309: Add "forced" display of particles
efeeab2f Add index to README.md for easier navigation
f502bc6f Update to Minecraft 1.13.1

CraftBukkit Changes:
d0bb0a1d Fix some tests randomly failing
997d378d Fix client stall in specific teleportation scenarios
b3dc2366 SPIGOT-4307: Fix hacky API for banners on shields
2a271162 SPIGOT-4301: Fix more invalid enchants
5d0d83bb SPIGOT-4309: Add "forced" display of particles
a6772578 Add additional tests for CraftBlockData
ce1af0c3 Update to Minecraft 1.13.1

Spigot Changes:
2440e189 Rebuild patches
4ecffced Update to Minecraft 1.13.1
2018-08-26 20:51:39 -04:00

67 lines
3 KiB
Diff

From c033b7ac3b55f3523700a96a450368327b68c2d9 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Mon, 23 Jul 2018 23:40:04 -0400
Subject: [PATCH] Optimize Region File Cache
CraftBukkit added synchronization to read and write methods. This adds
much more contention on this object for accessing region files, as
the entire read and write of NBT data is now a blocking operation.
This causes issues when something then simply needs to check if a chunk exists
on the main thread, causing a block...
However, this synchronization was unnecessary, because there is already
enough synchronization done to keep things safe
1) Obtaining a Region File: Those methods are still static synchronized.
Meaning we can safely obtain a Region File concurrently.
2) RegionFile data access: Methods reading and manipulating data from
a region file are also marked synchronized, ensuring that no 2 processes
are reading or writing data at the same time.
3) Checking a region file for chunkExists: getOffset is also synchronized
ensuring that even if a chunk is currently being written, it will be safe.
By removing these synchronizations, we reduce the locking to only
when data is being write or read.
GZIP compression and NBT Buffer creation will no longer be part of the
synchronized context, reducing lock times.
Ultimately: This brings us back to Vanilla, which has had no indication of region file loss.
diff --git a/src/main/java/net/minecraft/server/RegionFileCache.java b/src/main/java/net/minecraft/server/RegionFileCache.java
index c0ab543b91..15666325ea 100644
--- a/src/main/java/net/minecraft/server/RegionFileCache.java
+++ b/src/main/java/net/minecraft/server/RegionFileCache.java
@@ -99,7 +99,7 @@ public class RegionFileCache {
@Nullable
// CraftBukkit start - call sites hoisted for synchronization
- public static synchronized NBTTagCompound read(File file, int i, int j) throws IOException {
+ public static NBTTagCompound read(File file, int i, int j) throws IOException { // Paper - remove synchronization
RegionFile regionfile = a(file, i, j);
DataInputStream datainputstream = regionfile.a(i & 31, j & 31);
@@ -112,7 +112,7 @@ public class RegionFileCache {
}
@Nullable
- public static synchronized void write(File file, int i, int j, NBTTagCompound nbttagcompound) throws IOException {
+ public static void write(File file, int i, int j, NBTTagCompound nbttagcompound) throws IOException {
int attempts = 0; Exception laste = null; while (attempts++ < 5) { try { // Paper
RegionFile regionfile = a(file, i, j);
@@ -138,7 +138,7 @@ public class RegionFileCache {
// Paper end
}
- public static synchronized boolean chunkExists(File file, int i, int j) {
+ public static boolean chunkExists(File file, int i, int j) { // Paper - remove synchronization
RegionFile regionfile = b(file, i, j);
return regionfile != null ? regionfile.d(i & 31, j & 31) : false;
--
2.18.0