Since one of the later 1.6 snapshots (I cannot recall which), minecraft servers have been unusable for me. The server starts up fine, but then over time the server gets unstable and the log just fills with cannot keep up messages. Timeouts begin to occur all the time and block lag occurs. This isn't a hardware issue, because the servers worked with 1.5 and lower with 20+ people on no problem. Now the server becomes unstable with no one on. I can however, host more than 20 people by just hosting it as a LAN world then giving my friends that port and forwarding it through the router. That results in no lag or performance degrading. RAM on server set to 6gb and computer has 16gb.
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anyone want to help fix this?
GoodKingFilms
I guess the lag comes from Zombies. Look at this bug: https://mojang.atlassian.net/browse/MC-17630
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I don't know though, because the issue occurs even when on peaceful or doMobSpawning= false is activated
kumasasa
What is the command line for starting the server ? Too less RAM for the JVM ?
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I attached the launcher script to the bug report, the server max only ever has 5 people on it, but usually only 2. Lag is experienced with only one person as well.
kumasasa
Strange.
My own (windows) server runs without problems with java.exe -Xmx1024M -Xms1024M -jar minecraft_server.jar.
Try to reduce the minimum memory (-Xms to 1 or 2 G and let do the JVM garbage colletor it's work.
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I just launched it with those settings, but it had the same result. I can't remember which version this started occurring on, but i think it was a around the second snapshot. My friend (windows) has been having the same issue, so I don't think it's mac but I very well could be wrong.
kumasasa
Your oriignal entry was
Minecraft Server Performance Degrades Severely Over Time
If you experience this immediately after start of the server then it's clearly MC-17630
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It is over time, the performance is perfect when it starts up, but then just goes downhill from there. Look at the server log I attached and note the time stamps of the server can't keep up messages.
kumasasa
2013-07-05 17:26:51 [INFO] Starting minecraft server version 1.6.2
...
2013-07-05 17:27:51 [WARNING] Can't keep up! Did the system time change, or is the server overloaded?60 seconds after start - that's immediately. No sign for a memory leak which accumulates over hours, days or even weeks.
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The main reason I'm think it's not zombies though is because it occurs on peaceful mode too. Also, the server is playable on for about 5 minutes after launch. Then block lag starts. Then at about 10 minutes of play time in, time outs occur like there's no tomorrow. The can't keep up messages also seem to increase in frequency.
kumasasa
Please attach the a ZIP or 7Z of the world here and force a crash by pressing F3 + C for 10 seconds while ingame and attach the crash report here.
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The world was generated in 1.3, and as such is very large. Even after using a zip, it is still 114MB. This is too large to upload, so I had to upload to Google Drive. Here is the link to that: https://docs.google.com/file/d/0B0C5g0mLYXUDMlBZSk9QaXNuVDA/edit?usp=sharing
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It is worth noting though, that this occurs on this survival world, "air" maps such as Sethbling's supercraftbros, and super flat worlds, but it takes longer to start lagging on the "air" and super flat worlds.
kumasasa
Downloaded your world, played 10 minutes without any complain of the server (Server and client running on same machine)
Is there a specific location where to go ? Found a subway near spawn, drove it to it's end point.
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This is very weird. I just tried playing on the same world, and the server didnt have any problems. It only sometimes does, but it happens 99% of the time. The Mac OS X 10.9 beta was just updated to build (13A524d) today, so that may have fixed the problem, but I don't know, I will try again tomorrow and see if the problem returns.
kumasasa
I can recreate the lag when creating Zombies, then MC-17630 kicks in.
The villagers around spawn are (deliberately) unreachable...
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I have been able to confirm it is MC-17630 in certain circumstances. I think the latest build of Mac OS X 10.9 fixed the problem with the server having problems on peaceful worlds. Here is a screen-recording of the problem: https://www.youtube.com/watch?v=8rh-qTdBoY4
kumasasa
Thanks for the video. That's proof enough for MC-17630.