why can't i give my bukkit server more memory?

Discussion in 'Bukkit Help' started by jullleee, Feb 7, 2011.

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  1. Offline

    jullleee

    hey, when im starting my server i use


    @echo off
    java -Xms1548M -Xmx1548M -jar craftbukkit-0.0.1-SNAPSHOT.jar nogui
    pause

    but if i change it to Xms2548M -Xmx2548M it says that it cound not get that much. but i have 8 GB of rams :S
    thanks in advance.

    P.S if i check how much it's takes on my computer with Xms1548M -Xmx1548M it says that the server only take around 20-30% ;S
     
  2. Offline

    TnT

    You are using a 32 bit version of Java. You need to use a x64 version to allocate more RAM.
     
  3. Offline

    jullleee

    THANKS!
    i can use this one now :D

    @echo off
    java -Xms8048M -Xmx8048M -jar craftbukkit-0.0.1-SNAPSHOT.jar nogui
    pause
     
  4. Offline

    TnT

    <in my best valley girl impression>That command is SOOOOO last week.

    Use this command instead:
    Code:
    java -Xincgc -Xmx8G -jar craftbukkit-0.0.1-SNAPSHOT.jar nogui
     
  5. Offline

    jullleee

    ty :D:D:D
     
  6. Offline

    mindless728

    i see you posting this everywhere, have you actually done some benchmarks on it (or at least link some) as from what it sounds like the incremental GC loses performance as the GC performance is supposed to drop by ~10%

    -Xincgc
    Enable the incremental garbage collector. The incremental garbage collector, which is off by default, will eliminate occasional garbage-collection pauses during program execution. However, it can lead to a roughly 10% decrease in overall GC performance.

    from: Java - The Java Application Launcher
     
  7. Offline

    TnT

    Don't use it if you don't want to. I have no way of properly benchmarking Java commands, all I can do is list my results with it. When I began using it, RAM usage on my server decreased by 25% (on idle, and significantly more than that while under load), and my users noticed significant lag reduction. While it may have decreased GC performance by 10%, it has improved overall server performance for me. Others have said the same, hence I promote it over the old command.
    Have you done any benchmarks? Do you know any way to accurately benchmark these flags?
     
  8. Offline

    mindless728

    don't get me wrong this isn't an attack on you at all, i was just wondering if it was from personal experience or from an actual benchmark and i was just posting what oracle says about using this flag and wondering if it affects your performance at all

    and to answer your questions, no i don't really know a good way to benchmark this, i wish i did because i would
     
  9. Offline

    TnT

    Personal experience and the personal experience of others. Nothing that can be used to hold up in court.

    Yes it has - a positive performance boost. I find its a much better than commands such as this:
    Code:
    -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+CMSIncrementalPacing -XX:ParallelGCThreads=2 -XX:+AggressiveOpts
    As do I, because I would have solid information, as opposed to undocumented test cases.
     
  10. Offline

    mindless728

    i'll look around and see if i find anything, but i doubt it its kind of going to be personal experience more than likely
     
  11. Offline

    TnT

    Anything specifically related to running the Minecraft server (whether its hMod, Bukkit, etc) are likely going to be personal experience. If I knew of a Java "benchmark" program, I could put it through the test myself.

    Otherwise the best I could give is a "top" display of the Java process, and run it under different conditions. I could do this for idle, but that's not going to let you know if the users see lag or not, or what the results would be under load. I don't have enough hardware to throw up a temporary testing server for a load test.
     
  12. Offline

    mindless728

    i might do the tests on my laptop as it is more than capable for this, though between college and work there isn't a whole lot of time
     
  13. Offline

    Plague

    Why is everybody so obsessed with RAM usage on the server, I mean also those that have more physical RAM than set to java to use. Is it a sickness or something? :)

    Too bad that the only thing to test it is the "laggy feel" of the game... Couldn't we come up with simething? like measuring some actions using a plugin that prints time? I tested warping to places, but that's an I/O problem, not RAM right?
     
  14. Offline

    TnT

    Its more for people who are running on systems with limited RAM. I want to squeeze whatever performance I can get out of my Java process, and the GC flags help with that, more than just RAM usage.

    We could run a bunch of tests sure. I'm not sure it would given anyone real proof, but we could try.
    The loading and unloading of chunks is most taxing on I/O, but RAM and CPU also play important roles.
     
  15. Offline

    s0nge

    is " java -Xincgc -Xmx7G -jar craftbukkit-0.0.1-SNAPSHOT.jar nogui " the correct line for
    allowing my server to use 7g ram?
     
  16. Offline

    TnT

    Yes, that will work.
     
  17. Offline

    s0nge

    Thank you sir =)
     
  18. Offline

    Eddy1217

    I cant seem to use anything over 1G of ram, when i have 4Gb of ram on my system...
    Says not enough to create a dump or something?
    Any halp?
     
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