MC-509Exception in server tick loop :: ConcurrentModificationException
It was not obvious what precipitated this crash. There were several cheaters attempting to fly, but they would get automatically kicked and nothing obvious seemed to go wrong after that. Then, out of nowhere, the server crashed.
An administrator did perform an RCON command right before the exception. This may or may not be related. The RCON command was:
give <player name> 394 16
---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3
Time: 10/25/12 9:46 AM
Description: Exception in server tick loop
java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:894)
at java.util.HashMap$KeyIterator.next(HashMap.java:928)
at hz.a(SourceFile:90)
at net.minecraft.server.MinecraftServer.r(SourceFile:721)
at hg.r(SourceFile:233)
at net.minecraft.server.MinecraftServer.q(SourceFile:661)
at net.minecraft.server.MinecraftServer.run(SourceFile:595)
at fp.run(SourceFile:818)
Relevant Details:
- Minecraft Version: 1.4.2
- Operating System: Mac OS X (x86_64) version 10.8.1
- Java Version: 1.7.0_07, Oracle Corporation
- Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
- Memory: 703529376 bytes (670 MB) / 3221225472 bytes (3072 MB) up to 3221225472 bytes (3072 MB)
- JVM Flags: 5 total; -Xmx3G -Xms3G -Xloggc:server_gc.log -XX:+UseG1GC -XX:+DisableExplicitGC
- AABB Pool Size: 24234 (1357104 bytes; 1 MB) allocated, 20708 (1159648 bytes; 1 MB) used
- Is Modded: Unknown (can't tell)
- Profiler Position: N/A (disabled)
- Vec3 Pool Size: 37661 (2109016 bytes; 2 MB) allocated, 19642 (1099952 bytes; 1 MB) used
- Player Count: 9 / 20
- World swim2 Players: 0 total; []
- World swim2 Chunk Stats: ServerChunkCache: 0 Drop: 0
- Type: Dedicated Server
Linked Issues
is duplicated by1
Created Issue:
Exception in server tick loop :: ConcurrentModificationException
It was not obvious what precipitated this crash. There were several cheaters attempting to fly, but they would get automatically kicked and nothing obvious seemed to go wrong after that. Then, out of nowhere, the server crashed.
An administrator did perform an RCON command right before the exception. This may or may not be related. The RCON command was:
noformat}}give <player name> 394 16{{noformat
noformat---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3Time: 10/25/12 9:46 AM
Description: Exception in server tick loopjava.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:894)
at java.util.HashMap$KeyIterator.next(HashMap.java:928)
at hz.a(SourceFile:90)
at net.minecraft.server.MinecraftServer.r(SourceFile:721)
at hg.r(SourceFile:233)
at net.minecraft.server.MinecraftServer.q(SourceFile:661)
at net.minecraft.server.MinecraftServer.run(SourceFile:595)
at fp.run(SourceFile:818)Relevant Details:
- Minecraft Version: 1.4.2
- Operating System: Mac OS X (x86_64) version 10.8.1
- Java Version: 1.7.0_07, Oracle Corporation
- Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
- Memory: 703529376 bytes (670 MB) / 3221225472 bytes (3072 MB) up to 3221225472 bytes (3072 MB)
- JVM Flags: 5 total; -Xmx3G -Xms3G -Xloggc:server_gc.log -XX:+UseG1GC -XX:+DisableExplicitGC
- AABB Pool Size: 24234 (1357104 bytes; 1 MB) allocated, 20708 (1159648 bytes; 1 MB) used
- Is Modded: Unknown (can't tell)
- Profiler Position: N/A (disabled)
- Vec3 Pool Size: 37661 (2109016 bytes; 2 MB) allocated, 19642 (1099952 bytes; 1 MB) used
- Player Count: 9 / 20
- World swim2 Players: 0 total; []
- World swim2 Chunk Stats: ServerChunkCache: 0 Drop: 0
- Type: Dedicated Server{{noformat}}
It was not obvious what precipitated this crash. There were several cheaters attempting to fly, but they would get automatically kicked and nothing obvious seemed to go wrong after that. Then, out of nowhere, the server crashed.
An administrator did perform an RCON command right before the exception. This may or may not be related. The RCON command was:
noformat}}give <player name> 394 16{{noformat
noformat---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3Time: 10/25/12 9:46 AM
Description: Exception in server tick loopjava.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:894)
at java.util.HashMap$KeyIterator.next(HashMap.java:928)
at hz.a(SourceFile:90)
at net.minecraft.server.MinecraftServer.r(SourceFile:721)
at hg.r(SourceFile:233)
at net.minecraft.server.MinecraftServer.q(SourceFile:661)
at net.minecraft.server.MinecraftServer.run(SourceFile:595)
at fp.run(SourceFile:818)Relevant Details:
- Minecraft Version: 1.4.2
- Operating System: Mac OS X (x86_64) version 10.8.1
- Java Version: 1.7.0_07, Oracle Corporation
- Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
- Memory: 703529376 bytes (670 MB) / 3221225472 bytes (3072 MB) up to 3221225472 bytes (3072 MB)
- JVM Flags: 5 total; -Xmx3G -Xms3G -Xloggc:server_gc.log -XX:+UseG1GC -XX:+DisableExplicitGC
- AABB Pool Size: 24234 (1357104 bytes; 1 MB) allocated, 20708 (1159648 bytes; 1 MB) used
- Is Modded: Unknown (can't tell)
- Profiler Position: N/A (disabled)
- Vec3 Pool Size: 37661 (2109016 bytes; 2 MB) allocated, 19642 (1099952 bytes; 1 MB) used
- Player Count: 9 / 20
- World swim2 Players: 0 total; []
- World swim2 Chunk Stats: ServerChunkCache: 0 Drop: 0
- Type: Dedicated Server{{noformat}}
It was not obvious what precipitated this crash. There were several cheaters attempting to fly, but they would get automatically kicked and nothing obvious seemed to go wrong after that. Then, out of nowhere, the server crashed.
An administrator did perform an RCON command right before the exception. This may or may not be related. The RCON command was:
give <player name> 394 16{noformat}}---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3Time: 10/25/12 9:46 AM
Description: Exception in server tick loopjava.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:894)
at java.util.HashMap$KeyIterator.next(HashMap.java:928)
at hz.a(SourceFile:90)
at net.minecraft.server.MinecraftServer.r(SourceFile:721)
at hg.r(SourceFile:233)
at net.minecraft.server.MinecraftServer.q(SourceFile:661)
at net.minecraft.server.MinecraftServer.run(SourceFile:595)
at fp.run(SourceFile:818)Relevant Details:
- Minecraft Version: 1.4.2
- Operating System: Mac OS X (x86_64) version 10.8.1
- Java Version: 1.7.0_07, Oracle Corporation
- Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
- Memory: 703529376 bytes (670 MB) / 3221225472 bytes (3072 MB) up to 3221225472 bytes (3072 MB)
- JVM Flags: 5 total; -Xmx3G -Xms3G -Xloggc:server_gc.log -XX:+UseG1GC -XX:+DisableExplicitGC
- AABB Pool Size: 24234 (1357104 bytes; 1 MB) allocated, 20708 (1159648 bytes; 1 MB) used
- Is Modded: Unknown (can't tell)
- Profiler Position: N/A (disabled)
- Vec3 Pool Size: 37661 (2109016 bytes; 2 MB) allocated, 19642 (1099952 bytes; 1 MB) used
- Player Count: 9 / 20
- World swim2 Players: 0 total; []
- World swim2 Chunk Stats: ServerChunkCache: 0 Drop: 0
- Type: Dedicated Server
It was not obvious what precipitated this crash. There were several cheaters attempting to fly, but they would get automatically kicked and nothing obvious seemed to go wrong after that. Then, out of nowhere, the server crashed.
An administrator did perform an RCON command right before the exception. This may or may not be related. The RCON command was:
give <player name> 394 16{noformat}}---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3Time: 10/25/12 9:46 AM
Description: Exception in server tick loopjava.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:894)
at java.util.HashMap$KeyIterator.next(HashMap.java:928)
at hz.a(SourceFile:90)
at net.minecraft.server.MinecraftServer.r(SourceFile:721)
at hg.r(SourceFile:233)
at net.minecraft.server.MinecraftServer.q(SourceFile:661)
at net.minecraft.server.MinecraftServer.run(SourceFile:595)
at fp.run(SourceFile:818)Relevant Details:
- Minecraft Version: 1.4.2
- Operating System: Mac OS X (x86_64) version 10.8.1
- Java Version: 1.7.0_07, Oracle Corporation
- Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
- Memory: 703529376 bytes (670 MB) / 3221225472 bytes (3072 MB) up to 3221225472 bytes (3072 MB)
- JVM Flags: 5 total; -Xmx3G -Xms3G -Xloggc:server_gc.log -XX:+UseG1GC -XX:+DisableExplicitGC
- AABB Pool Size: 24234 (1357104 bytes; 1 MB) allocated, 20708 (1159648 bytes; 1 MB) used
- Is Modded: Unknown (can't tell)
- Profiler Position: N/A (disabled)
- Vec3 Pool Size: 37661 (2109016 bytes; 2 MB) allocated, 19642 (1099952 bytes; 1 MB) used
- Player Count: 9 / 20
- World swim2 Players: 0 total; []
- World swim2 Chunk Stats: ServerChunkCache: 0 Drop: 0
- Type: Dedicated Server
It was not obvious what precipitated this crash. There were several cheaters attempting to fly, but they would get automatically kicked and nothing obvious seemed to go wrong after that. Then, out of nowhere, the server crashed.
An administrator did perform an RCON command right before the exception. This may or may not be related. The RCON command was:
give <player name> 394 16---- Minecraft Crash Report ---- // Don't be sad, have a hug! <3 Time: 10/25/12 9:46 AM Description: Exception in server tick loop java.util.ConcurrentModificationException at java.util.HashMap$HashIterator.nextEntry(HashMap.java:894) at java.util.HashMap$KeyIterator.next(HashMap.java:928) at hz.a(SourceFile:90) at net.minecraft.server.MinecraftServer.r(SourceFile:721) at hg.r(SourceFile:233) at net.minecraft.server.MinecraftServer.q(SourceFile:661) at net.minecraft.server.MinecraftServer.run(SourceFile:595) at fp.run(SourceFile:818) Relevant Details: - Minecraft Version: 1.4.2 - Operating System: Mac OS X (x86_64) version 10.8.1 - Java Version: 1.7.0_07, Oracle Corporation - Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation - Memory: 703529376 bytes (670 MB) / 3221225472 bytes (3072 MB) up to 3221225472 bytes (3072 MB) - JVM Flags: 5 total; -Xmx3G -Xms3G -Xloggc:server_gc.log -XX:+UseG1GC -XX:+DisableExplicitGC - AABB Pool Size: 24234 (1357104 bytes; 1 MB) allocated, 20708 (1159648 bytes; 1 MB) used - Is Modded: Unknown (can't tell) - Profiler Position: N/A (disabled) - Vec3 Pool Size: 37661 (2109016 bytes; 2 MB) allocated, 19642 (1099952 bytes; 1 MB) used - Player Count: 9 / 20 - World swim2 Players: 0 total; [] - World swim2 Chunk Stats: ServerChunkCache: 0 Drop: 0 - Type: Dedicated Server
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This is a duplicate of MC-509 - which is about dedicated server, but the crash is the same.
Description: Exception in server tick loop
java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:894)
at java.util.HashMap$KeyIterator.next(HashMap.java:928)
at hz.a(SourceFile:90)
at net.minecraft.server.MinecraftServer.r(SourceFile:721)
at hg.r(SourceFile:233)
at net.minecraft.server.MinecraftServer.q(SourceFile:661)
at net.minecraft.server.MinecraftServer.run(SourceFile:595)
at fp.run(SourceFile:818)
Description: Exception ticking world java.util.ConcurrentModificationException at java.util.HashMap$HashIterator.nextEntry(Unknown Source) at java.util.HashMap$KeyIterator.next(Unknown Source) at iy.b(SourceFile:196) at iz.b(SourceFile:122) at net.minecraft.server.MinecraftServer.r(SourceFile:454) at hz.r(SourceFile:255) at net.minecraft.server.MinecraftServer.q(SourceFile:397) at net.minecraft.server.MinecraftServer.run(SourceFile:331) at gp.run(SourceFile:573)
Description: Exception ticking world java.lang.NullPointerException at iy.b(SourceFile:199) at iz.b(SourceFile:122) at net.minecraft.server.MinecraftServer.r(SourceFile:454) at hz.r(SourceFile:255) at net.minecraft.server.MinecraftServer.q(SourceFile:397) at net.minecraft.server.MinecraftServer.run(SourceFile:331) at gp.run(SourceFile:573)
Conclusion: Not dupe of MC-509, but MC-12485 dupe of this one.
It appears that RCON commands do indeed have something to do with it, but only when the server has been up for quite a while.
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
I have seen a great many ConcurrentModificationException spamming the console in 1.4.5 while the server is being DDoSed. Likely, this is a side effect of the garbage collector being overworked. This is one of those "tricky-to-re-produce" situations. I can't exactly ask someone to DDoS my server so I can test it.
Your call.
I just got something similar in 1.5. Brand new world, no RCON. There were two of us on, but the trace says just one, so this might have happened just after the other guy disconnected. No mods, no DDoS, nothing special at all.
+1 on a vanilla server
// You should try our sister game, Minceraft!
Nice witty comment you got in the crash log .
Actually, confirmed.
I have not observed this situation for quite some time. I believe it was finally addressed in 1.6.
Thanks for the feedback.
I haven't seen this in a long time. Currently running 1.7.2. I suspect it is fixed.
No new reports of this kind since 1.8, but maybe this ticket got superseeded by
MC-72390