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01a13871de
Patch documentation to come Issues with the old system that are fixed now: - World generation does not scale with cpu cores effectively. - Relies on the main thread for scheduling and maintaining chunk state, dropping chunk load/generate rates at lower tps. - Unreliable prioritisation of chunk gen/load calls that block the main thread. - Shutdown logic is utterly unreliable, as it has to wait for all chunks to unload - is it guaranteed that the chunk system is in a state on shutdown that it can reliably do this? Watchdog shutdown also typically failed due to thread checks, which is now resolved. - Saving of data is not unified (i.e can save chunk data without saving entity data, poses problems for desync if shutdown is really abnormal. - Entities are not loaded with chunks. This caused quite a bit of headache for Chunk#getEntities API, but now the new chunk system loads entities with chunks so that they are ready whenever the chunk loads in. Effectively brings the behavior back to 1.16 era, but still storing entities in their own separate regionfiles. The above list is not complete. The patch documentation will complete it. New chunk system hard relies on starlight and dataconverter, and most importantly the new concurrent utilities in ConcurrentUtil. Some of the old async chunk i/o interface (i.e the old file io thread reroutes _some_ calls to the new file io thread) is kept for plugin compat reasons. It will be removed in the next major version of minecraft. The old legacy chunk system patches have been moved to the removed folder in case we need them again.
55 lines
2.8 KiB
Diff
55 lines
2.8 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, 12 Sep 2020 17:21:38 -0400
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Subject: [PATCH] Cache DataFixerUpper Rewrite Rules on demand
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Mojang precaches every single potential rewrite rule that could ever
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exist on server startup. This includes rules from all the way back to versions from 6+ years ago.
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This is the source of why the server hogs every CPU core at 100% every start.
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For anyone who hard resets for updates or has force upgraded their entire world, this
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results in completely wasted cpu cycles.
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This massive CPU usage also delays server startup time.
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We improve this by making "min version to precache" that defaults to a future version
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so that no rewrite rules are precached.
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someone who expects to be converting a lot chunks could theoretically set
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-DPaper.minPrecachedDatafixVersion=<dataVersionConvertingFrom> as a startup
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parameter and only build from that point on.
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However this will likely never be needed as the server will still run
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the same cache logic on demand when it's actually needed. The only
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cost would be some delay on the FIRST chunk conversion, but paper already
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runs chunk conversions on another thread so this will likely never be
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a concern for TPS.
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This patch will significantly reduce CPU use on startup, reduce memory usage,
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and improve server startup time.
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diff --git a/src/main/java/com/mojang/datafixers/DataFixerBuilder.java b/src/main/java/com/mojang/datafixers/DataFixerBuilder.java
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index d25f106ab64c90438f521a2c6fa944bdedc1969a..3d5e52d997a8e7d7f3b000e3737d30762aae2ca1 100644
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--- a/src/main/java/com/mojang/datafixers/DataFixerBuilder.java
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+++ b/src/main/java/com/mojang/datafixers/DataFixerBuilder.java
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@@ -28,8 +28,10 @@ public class DataFixerBuilder {
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private final Int2ObjectSortedMap<Schema> schemas = new Int2ObjectAVLTreeMap<>();
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private final List<DataFix> globalList = Lists.newArrayList();
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private final IntSortedSet fixerVersions = new IntAVLTreeSet();
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+ private final int minDataFixPrecacheVersion; // Paper
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public DataFixerBuilder(final int dataVersion) {
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+ minDataFixPrecacheVersion = Integer.getInteger("Paper.minPrecachedDatafixVersion", dataVersion+1) * 10; // Paper - default to precache nothing - mojang stores versions * 10 to allow for 'sub versions'
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this.dataVersion = dataVersion;
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}
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@@ -74,6 +76,7 @@ public class DataFixerBuilder {
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final IntBidirectionalIterator iterator = fixerUpper.fixerVersions().iterator();
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while (iterator.hasNext()) {
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final int versionKey = iterator.nextInt();
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+ if (versionKey < minDataFixPrecacheVersion) continue; // Paper
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final Schema schema = schemas.get(versionKey);
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for (final String typeName : schema.types()) {
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final CompletableFuture<Void> future = CompletableFuture.runAsync(() -> {
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