Paper/patches/server/0134-Properly-handle-async-calls-to-restart-the-server.patch
Nassim Jahnke 789bc79280
Updated Upstream (Bukkit/CraftBukkit/Spigot) (#6457)
Upstream has released updates that appear to apply and compile correctly.
This update has not been tested by PaperMC and as with ANY update, please do your own testing

Bukkit Changes:
c9a46ebf #653: Add World#spawn with randomizeData parameter
e49c2e3a Damageable should extend ItemMeta
01ff04f4 SPIGOT-5880, SPIGOT-5567: New ChunkGenerator API
ca5b4b1a SPIGOT-6697: Deprecate generateTree with BlockChangeDelegate as it does not handle tiles

CraftBukkit Changes:
7c8bbcbe SPIGOT-6716: Preserve the order of stored enchantments of enchanted books.
18027d02 #914: Add World#spawn with randomizeData parameter
3cad0316 SPIGOT-6714: Don't fire PlayerBucketEvent when empty
8c6d60cf Fix server crash with BlockPopulator when entities are at a negative chunk border
4f6bcc84 SPIGOT-5880, SPIGOT-5567: New ChunkGenerator API
78d5b35b SPIGOT-6697: Restore generateTree with BlockChangeDelegate behaviour
15792f0d Rebuild patch
c949675e SPIGOT-6713: Cancelling EntityTransformEvent Causes Deceased Slimes To Not Despawn
a955f15c Fix issues with new ChunkGenerator API
a0a37f41 SPIGOT-6630: Replacing an enchantment on an item creates a conflict error

Spigot Changes:
b166a49b Rebuild patches
3c1fc60a SPIGOT-6693: Composters only take in one item at custom hopper speeds
2021-08-25 09:59:26 +02:00

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12 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Zach Brown <zach.brown@destroystokyo.com>
Date: Fri, 12 May 2017 23:34:11 -0500
Subject: [PATCH] Properly handle async calls to restart the server
The watchdog thread calls the server restart function asynchronously. Prior to
this change, it attempted to do several non-safe operations from the watchdog
thread, rather than the main. Specifically, because of a separate upstream change,
it causes player entities to be ticked asynchronously, among other things.
This is dangerous.
This patch moves the old handling into a synchronous variant, for calls from the
restart command, and adds separate handling for async calls, such as those from
the watchdog thread.
When calling from the watchdog thread, we cannot assume the main thread is in a
tickable state; it may be completely deadlocked. In order to handle this, we mark
the server as stopping, in order to account for situations where the server should
complete a tick reasonbly soon, i.e. 99% of cases.
Should the server not enter a state where it is stopping within 10 seconds, We
will assume that the server has in fact deadlocked and will proceed to force
kill the server.
This modification does not force restart the server should we actually enter a
deadlocked state where the server is stopping, whereas this will in most cases
exit within a reasonable amount of time, to put a fixed limit on a process that
will have plugins and worlds saving to the disk has a high potential to result
in corruption/dataloss.
diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index 6f46c66890429e438c484e3a5f425936bd7d4130..2a064d7d6b0ee97c9e192ea8b4b601fac66a8574 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -232,6 +232,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
public final Map<ResourceKey<Level>, ServerLevel> levels;
private PlayerList playerList;
private volatile boolean running;
+ private volatile boolean isRestarting = false; // Paper - flag to signify we're attempting to restart
private boolean stopped;
private int tickCount;
protected final Proxy proxy;
@@ -940,7 +941,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
if (this.playerList != null) {
MinecraftServer.LOGGER.info("Saving players");
this.playerList.saveAll();
- this.playerList.removeAll();
+ this.playerList.removeAll(this.isRestarting); // Paper
try { Thread.sleep(100); } catch (InterruptedException ex) {} // CraftBukkit - SPIGOT-625 - give server at least a chance to send packets
}
@@ -1006,6 +1007,12 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
}
public void halt(boolean flag) {
+ // Paper start - allow passing of the intent to restart
+ this.safeShutdown(flag, false);
+ }
+ public void safeShutdown(boolean flag, boolean isRestarting) {
+ this.isRestarting = isRestarting;
+ // Paper end
this.running = false;
if (flag) {
try {
diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index b08b11bfbc3441fc2899a5e72d7a388383781955..24add1cd1f865012c5382548e415218d481ecefe 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -1141,8 +1141,15 @@ public abstract class PlayerList {
}
public void removeAll() {
+ // Paper start - Extract method to allow for restarting flag
+ this.removeAll(false);
+ }
+
+ public void removeAll(boolean isRestarting) {
+ // Paper end
// CraftBukkit start - disconnect safely
for (ServerPlayer player : this.players) {
+ if (isRestarting) player.connection.disconnect(org.spigotmc.SpigotConfig.restartMessage); else // Paper
player.connection.disconnect(this.server.server.shutdownMessage()); // CraftBukkit - add custom shutdown message // Paper - Adventure
}
// CraftBukkit end
diff --git a/src/main/java/org/spigotmc/RestartCommand.java b/src/main/java/org/spigotmc/RestartCommand.java
index 94d8ba376cd1f024b244654cac9bb62bb19e3060..a142a56a920e153ed84c08cece993f10d76f7793 100644
--- a/src/main/java/org/spigotmc/RestartCommand.java
+++ b/src/main/java/org/spigotmc/RestartCommand.java
@@ -46,86 +46,134 @@ public class RestartCommand extends Command
org.spigotmc.AsyncCatcher.shuttingDown = true; // Paper
try
{
- String[] split = restartScript.split( " " );
- if ( split.length > 0 && new File( split[0] ).isFile() )
+ // Paper - extract method and cleanup
+ boolean isRestarting = addShutdownHook( restartScript );
+ if ( isRestarting )
{
- System.out.println( "Attempting to restart with " + restartScript );
+ System.out.println( "Attempting to restart with " + SpigotConfig.restartScript );
+ } else
+ {
+ System.out.println( "Startup script '" + SpigotConfig.restartScript + "' does not exist! Stopping server." );
+ }
+ // Stop the watchdog
+ WatchdogThread.doStop();
- // Disable Watchdog
- WatchdogThread.doStop();
+ shutdownServer( isRestarting );
+ // Paper end
+ } catch ( Exception ex )
+ {
+ ex.printStackTrace();
+ }
+ }
- // Kick all players
- for ( ServerPlayer p : (List<ServerPlayer>) MinecraftServer.getServer().getPlayerList().players )
- {
- p.connection.disconnect(SpigotConfig.restartMessage);
- }
- // Give the socket a chance to send the packets
- try
- {
- Thread.sleep( 100 );
- } catch ( InterruptedException ex )
- {
- }
- // Close the socket so we can rebind with the new process
- MinecraftServer.getServer().getConnection().stop();
+ // Paper start - sync copied from above with minor changes, async added
+ private static void shutdownServer(boolean isRestarting)
+ {
+ if ( MinecraftServer.getServer().isSameThread() )
+ {
+ // Kick all players
+ for ( ServerPlayer p : com.google.common.collect.ImmutableList.copyOf( MinecraftServer.getServer().getPlayerList().players ) )
+ {
+ p.connection.disconnect(SpigotConfig.restartMessage);
+ }
+ // Give the socket a chance to send the packets
+ try
+ {
+ Thread.sleep( 100 );
+ } catch ( InterruptedException ex )
+ {
+ }
- // Give time for it to kick in
- try
- {
- Thread.sleep( 100 );
- } catch ( InterruptedException ex )
- {
- }
+ closeSocket();
- // Actually shutdown
- try
- {
- MinecraftServer.getServer().close();
- } catch ( Throwable t )
- {
- }
+ // Actually shutdown
+ try
+ {
+ MinecraftServer.getServer().close(); // calls stop()
+ } catch ( Throwable t )
+ {
+ }
+
+ // Actually stop the JVM
+ System.exit( 0 );
- // This will be done AFTER the server has completely halted
- Thread shutdownHook = new Thread()
+ } else
+ {
+ // Mark the server to shutdown at the end of the tick
+ MinecraftServer.getServer().safeShutdown( false, isRestarting );
+
+ // wait 10 seconds to see if we're actually going to try shutdown
+ try
+ {
+ Thread.sleep( 10000 );
+ }
+ catch (InterruptedException ignored)
+ {
+ }
+
+ // Check if we've actually hit a state where the server is going to safely shutdown
+ // if we have, let the server stop as usual
+ if (MinecraftServer.getServer().isStopped()) return;
+
+ // If the server hasn't stopped by now, assume worse case and kill
+ closeSocket();
+ System.exit( 0 );
+ }
+ }
+ // Paper end
+
+ // Paper - Split from moved code
+ private static void closeSocket()
+ {
+ // Close the socket so we can rebind with the new process
+ MinecraftServer.getServer().getConnection().stop();
+
+ // Give time for it to kick in
+ try
+ {
+ Thread.sleep( 100 );
+ } catch ( InterruptedException ex )
+ {
+ }
+ }
+ // Paper end
+
+ // Paper start - copied from above and modified to return if the hook registered
+ private static boolean addShutdownHook(String restartScript)
+ {
+ String[] split = restartScript.split( " " );
+ if ( split.length > 0 && new File( split[0] ).isFile() )
+ {
+ Thread shutdownHook = new Thread()
+ {
+ @Override
+ public void run()
{
- @Override
- public void run()
+ try
{
- try
+ String os = System.getProperty( "os.name" ).toLowerCase(java.util.Locale.ENGLISH);
+ if ( os.contains( "win" ) )
{
- String os = System.getProperty( "os.name" ).toLowerCase(java.util.Locale.ENGLISH);
- if ( os.contains( "win" ) )
- {
- Runtime.getRuntime().exec( "cmd /c start " + restartScript );
- } else
- {
- Runtime.getRuntime().exec( "sh " + restartScript );
- }
- } catch ( Exception e )
+ Runtime.getRuntime().exec( "cmd /c start " + restartScript );
+ } else
{
- e.printStackTrace();
+ Runtime.getRuntime().exec( "sh " + restartScript );
}
+ } catch ( Exception e )
+ {
+ e.printStackTrace();
}
- };
-
- shutdownHook.setDaemon( true );
- Runtime.getRuntime().addShutdownHook( shutdownHook );
- } else
- {
- System.out.println( "Startup script '" + SpigotConfig.restartScript + "' does not exist! Stopping server." );
-
- // Actually shutdown
- try
- {
- MinecraftServer.getServer().close();
- } catch ( Throwable t )
- {
}
- }
- System.exit( 0 );
- } catch ( Exception ex )
+ };
+
+ shutdownHook.setDaemon( true );
+ Runtime.getRuntime().addShutdownHook( shutdownHook );
+ return true;
+ } else
{
- ex.printStackTrace();
+ return false;
}
}
+ // Paper end
+
}