PaperMC/patches/server/0024-Further-improve-server-tick-loop.patch
Bjarne Koll c5a10665b8
Remove wall-time / unused skip tick protection (#11412)
Spigot still maintains some partial implementation of "tick skipping", a
practice in which the MinecraftServer.currentTick field is updated not
by an increment of one per actual tick, but instead set to
System.currentTimeMillis() / 50. This behaviour means that the tracked
tick may "skip" a tick value in case a previous tick took more than the
expected 50ms.

To compensate for this in important paths, spigot/craftbukkit
implements "wall-time". Instead of incrementing/decrementing ticks on
block entities/entities by one for each call to their tick() method,
they instead increment/decrement important values, like
an ItemEntity's age or pickupDelay, by the difference of
`currentTick - lastTick`, where `lastTick` is the value of
`currentTick` during the last tick() call.

These "fixes" however do not play nicely with minecraft's simulation
distance as entities/block entities implementing the above behaviour
would "catch up" their values when moving from a non-ticking chunk to a
ticking one as their `lastTick` value remains stuck on the last tick in
a ticking chunk and hence lead to a large "catch up" once ticked again.

Paper completely removes the "tick skipping" behaviour (See patch
"Further-improve-server-tick-loop"), making the above precautions
completely unnecessary, which also rids paper of the previous described
incompatibility with non-ticking chunks.
2024-09-19 16:36:07 +02:00

233 lines
13 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Tue, 1 Mar 2016 23:09:29 -0600
Subject: [PATCH] Further improve server tick loop
Improves how the catchup buffer is handled, allowing it to roll both ways
increasing the effeciency of the thread sleep so it only will sleep once.
Also increases the buffer of the catchup to ensure server stays at 20 TPS unless extreme conditions
Previous implementation did not calculate TPS correctly.
Switch to a realistic rolling average and factor in std deviation as an extra reporting variable
diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index 49de4625c57689a3624ed421c0b03512507c97c3..46e03617bb32e4037d700c1b3698d397bd75de5c 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -296,7 +296,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
public org.bukkit.craftbukkit.CraftServer server;
public OptionSet options;
public org.bukkit.command.ConsoleCommandSender console;
- public static int currentTick = (int) (System.currentTimeMillis() / 50);
+ public static int currentTick; // Paper - improve tick loop
public java.util.Queue<Runnable> processQueue = new java.util.concurrent.ConcurrentLinkedQueue<Runnable>();
public int autosavePeriod;
public Commands vanillaCommandDispatcher;
@@ -305,7 +305,8 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
// Spigot start
public static final int TPS = 20;
public static final int TICK_TIME = 1000000000 / MinecraftServer.TPS;
- private static final int SAMPLE_INTERVAL = 100;
+ private static final int SAMPLE_INTERVAL = 20; // Paper - improve server tick loop
+ @Deprecated(forRemoval = true) // Paper
public final double[] recentTps = new double[ 3 ];
// Spigot end
public final io.papermc.paper.configuration.PaperConfigurations paperConfigurations; // Paper - add paper configuration files
@@ -1019,6 +1020,57 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
{
return ( avg * exp ) + ( tps * ( 1 - exp ) );
}
+
+ // Paper start - Further improve server tick loop
+ private static final long SEC_IN_NANO = 1000000000;
+ private static final long MAX_CATCHUP_BUFFER = TICK_TIME * TPS * 60L;
+ private long lastTick = 0;
+ private long catchupTime = 0;
+ public final RollingAverage tps1 = new RollingAverage(60);
+ public final RollingAverage tps5 = new RollingAverage(60 * 5);
+ public final RollingAverage tps15 = new RollingAverage(60 * 15);
+
+ public static class RollingAverage {
+ private final int size;
+ private long time;
+ private java.math.BigDecimal total;
+ private int index = 0;
+ private final java.math.BigDecimal[] samples;
+ private final long[] times;
+
+ RollingAverage(int size) {
+ this.size = size;
+ this.time = size * SEC_IN_NANO;
+ this.total = dec(TPS).multiply(dec(SEC_IN_NANO)).multiply(dec(size));
+ this.samples = new java.math.BigDecimal[size];
+ this.times = new long[size];
+ for (int i = 0; i < size; i++) {
+ this.samples[i] = dec(TPS);
+ this.times[i] = SEC_IN_NANO;
+ }
+ }
+
+ private static java.math.BigDecimal dec(long t) {
+ return new java.math.BigDecimal(t);
+ }
+ public void add(java.math.BigDecimal x, long t) {
+ time -= times[index];
+ total = total.subtract(samples[index].multiply(dec(times[index])));
+ samples[index] = x;
+ times[index] = t;
+ time += t;
+ total = total.add(x.multiply(dec(t)));
+ if (++index == size) {
+ index = 0;
+ }
+ }
+
+ public double getAverage() {
+ return total.divide(dec(time), 30, java.math.RoundingMode.HALF_UP).doubleValue();
+ }
+ }
+ private static final java.math.BigDecimal TPS_BASE = new java.math.BigDecimal(1E9).multiply(new java.math.BigDecimal(SAMPLE_INTERVAL));
+ // Paper end
// Spigot End
protected void runServer() {
@@ -1033,7 +1085,10 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
// Spigot start
Arrays.fill( this.recentTps, 20 );
- long tickSection = Util.getMillis(), tickCount = 1;
+ // Paper start - further improve server tick loop
+ long tickSection = Util.getNanos();
+ long currentTime;
+ // Paper end - further improve server tick loop
while (this.running) {
long i;
@@ -1055,15 +1110,22 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
}
}
// Spigot start
- if ( tickCount++ % MinecraftServer.SAMPLE_INTERVAL == 0 )
- {
- long curTime = Util.getMillis();
- double currentTps = 1E3 / ( curTime - tickSection ) * MinecraftServer.SAMPLE_INTERVAL;
- this.recentTps[0] = MinecraftServer.calcTps( this.recentTps[0], 0.92, currentTps ); // 1/exp(5sec/1min)
- this.recentTps[1] = MinecraftServer.calcTps( this.recentTps[1], 0.9835, currentTps ); // 1/exp(5sec/5min)
- this.recentTps[2] = MinecraftServer.calcTps( this.recentTps[2], 0.9945, currentTps ); // 1/exp(5sec/15min)
- tickSection = curTime;
+ // Paper start - further improve server tick loop
+ currentTime = Util.getNanos();
+ if (++MinecraftServer.currentTick % MinecraftServer.SAMPLE_INTERVAL == 0) {
+ final long diff = currentTime - tickSection;
+ final java.math.BigDecimal currentTps = TPS_BASE.divide(new java.math.BigDecimal(diff), 30, java.math.RoundingMode.HALF_UP);
+ tps1.add(currentTps, diff);
+ tps5.add(currentTps, diff);
+ tps15.add(currentTps, diff);
+
+ // Backwards compat with bad plugins
+ this.recentTps[0] = tps1.getAverage();
+ this.recentTps[1] = tps5.getAverage();
+ this.recentTps[2] = tps15.getAverage();
+ tickSection = currentTime;
}
+ // Paper end - further improve server tick loop
// Spigot end
boolean flag = i == 0L;
@@ -1073,7 +1135,8 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
this.debugCommandProfiler = new MinecraftServer.TimeProfiler(Util.getNanos(), this.tickCount);
}
- MinecraftServer.currentTick = (int) (System.currentTimeMillis() / 50); // CraftBukkit
+ //MinecraftServer.currentTick = (int) (System.currentTimeMillis() / 50); // CraftBukkit // Paper - don't overwrite current tick time
+ lastTick = currentTime;
this.nextTickTimeNanos += i;
this.startMetricsRecordingTick();
this.profiler.push("tick");
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
index b3d4cb03f6d3951632fd15101aa68e130a43879b..90da60f7cdfe809c2035c9cd242f748ec8bf5eb0 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
@@ -2670,7 +2670,11 @@ public final class CraftServer implements Server {
@Override
public double[] getTPS() {
- return new double[]{0, 0, 0}; // TODO
+ return new double[] {
+ net.minecraft.server.MinecraftServer.getServer().tps1.getAverage(),
+ net.minecraft.server.MinecraftServer.getServer().tps5.getAverage(),
+ net.minecraft.server.MinecraftServer.getServer().tps15.getAverage()
+ };
}
// Paper start - adventure sounds
diff --git a/src/main/java/org/spigotmc/TicksPerSecondCommand.java b/src/main/java/org/spigotmc/TicksPerSecondCommand.java
index d9ec48be0fdd2bfea938aa29e36b0f6ffa839ab2..9eb2823cc8f83bad2626fc77578b0162d9ed5782 100644
--- a/src/main/java/org/spigotmc/TicksPerSecondCommand.java
+++ b/src/main/java/org/spigotmc/TicksPerSecondCommand.java
@@ -15,6 +15,12 @@ public class TicksPerSecondCommand extends Command
this.usageMessage = "/tps";
this.setPermission( "bukkit.command.tps" );
}
+ // Paper start
+ private static final net.kyori.adventure.text.Component WARN_MSG = net.kyori.adventure.text.Component.text()
+ .append(net.kyori.adventure.text.Component.text("Warning: ", net.kyori.adventure.text.format.NamedTextColor.RED))
+ .append(net.kyori.adventure.text.Component.text("Memory usage on modern garbage collectors is not a stable value and it is perfectly normal to see it reach max. Please do not pay it much attention.", net.kyori.adventure.text.format.NamedTextColor.GOLD))
+ .build();
+ // Paper end
@Override
public boolean execute(CommandSender sender, String currentAlias, String[] args)
@@ -24,22 +30,40 @@ public class TicksPerSecondCommand extends Command
return true;
}
- StringBuilder sb = new StringBuilder( ChatColor.GOLD + "TPS from last 1m, 5m, 15m: " );
- for ( double tps : MinecraftServer.getServer().recentTps )
- {
- sb.append( this.format( tps ) );
- sb.append( ", " );
+ // Paper start - Further improve tick handling
+ double[] tps = org.bukkit.Bukkit.getTPS();
+ net.kyori.adventure.text.Component[] tpsAvg = new net.kyori.adventure.text.Component[tps.length];
+
+ for ( int i = 0; i < tps.length; i++) {
+ tpsAvg[i] = TicksPerSecondCommand.format( tps[i] );
+ }
+
+ net.kyori.adventure.text.TextComponent.Builder builder = net.kyori.adventure.text.Component.text();
+ builder.append(net.kyori.adventure.text.Component.text("TPS from last 1m, 5m, 15m: ", net.kyori.adventure.text.format.NamedTextColor.GOLD));
+ builder.append(net.kyori.adventure.text.Component.join(net.kyori.adventure.text.JoinConfiguration.commas(true), tpsAvg));
+ sender.sendMessage(builder.asComponent());
+ if (args.length > 0 && args[0].equals("mem") && sender.hasPermission("bukkit.command.tpsmemory")) {
+ sender.sendMessage(net.kyori.adventure.text.Component.text()
+ .append(net.kyori.adventure.text.Component.text("Current Memory Usage: ", net.kyori.adventure.text.format.NamedTextColor.GOLD))
+ .append(net.kyori.adventure.text.Component.text(((Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()) / (1024 * 1024)) + "/" + (Runtime.getRuntime().totalMemory() / (1024 * 1024)) + " mb (Max: " + (Runtime.getRuntime().maxMemory() / (1024 * 1024)) + " mb)", net.kyori.adventure.text.format.NamedTextColor.GREEN))
+ );
+ if (!this.hasShownMemoryWarning) {
+ sender.sendMessage(WARN_MSG);
+ this.hasShownMemoryWarning = true;
+ }
}
- sender.sendMessage( sb.substring( 0, sb.length() - 2 ) );
- sender.sendMessage(ChatColor.GOLD + "Current Memory Usage: " + ChatColor.GREEN + ((Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()) / (1024 * 1024)) + "/" + (Runtime.getRuntime().totalMemory() / (1024 * 1024)) + " mb (Max: "
- + (Runtime.getRuntime().maxMemory() / (1024 * 1024)) + " mb)");
+ // Paper end
return true;
}
- private String format(double tps)
+ private boolean hasShownMemoryWarning; // Paper
+ private static net.kyori.adventure.text.Component format(double tps) // Paper - Made static
{
- return ( ( tps > 18.0 ) ? ChatColor.GREEN : ( tps > 16.0 ) ? ChatColor.YELLOW : ChatColor.RED ).toString()
- + ( ( tps > 20.0 ) ? "*" : "" ) + Math.min( Math.round( tps * 100.0 ) / 100.0, 20.0 );
+ // Paper
+ net.kyori.adventure.text.format.TextColor color = ( ( tps > 18.0 ) ? net.kyori.adventure.text.format.NamedTextColor.GREEN : ( tps > 16.0 ) ? net.kyori.adventure.text.format.NamedTextColor.YELLOW : net.kyori.adventure.text.format.NamedTextColor.RED );
+ String amount = Math.min(Math.round(tps * 100.0) / 100.0, 20.0) + (tps > 21.0 ? "*" : ""); // Paper - only print * at 21, we commonly peak to 20.02 as the tick sleep is not accurate enough, stop the noise
+ return net.kyori.adventure.text.Component.text(amount, color);
+ // Paper end
}
}