Java and the 1 CPU issue

Discussion in 'Bukkit Help' started by ChadTheDJ, Dec 27, 2011.

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    I know this may have been stated somewhere here but I couldn't find the forum searching for it.

    So I have a 64bit server that uses a 6 core processor. So, I found out recently that java is only using one of my cores and the other 5 are not even touched. This to me is crazy as I am paying for so much power but MC can only utilize 1/6th of the processing capabilities of my server.

    I read this forum post about putting flags to add garbage collection but still only uses one core:

    Is there a workaround for this? Is there a way to make java multi-threaded?

    Actually this is more meant for the bukkit help forum, whoops

    EDIT by Moderator: merged posts, please use the edit button instead of double posting.
    Last edited by a moderator: May 22, 2016
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    And off to the Bukkit Help forum it goes.
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    First off, the same thing happened to me. Right before I made my server I bought a 6core CPU but ended up selling it and buying a higher speed 4core, which hasn't failed me yet.

    As for Java, the programmer of the application decides how multithreaded it will be. Both the client and server of Minecraft have a few threads for different purposes, but the main one is huge and you cannot do anything about it. On the bright side, I run different types of servers on my machine which obviously use different threads than the Minecraft server. But in the end, 6 cores would be useless for me.
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    So my question after reading all of the tweaks on the thread I posted, there is no way to really utilize all 6 cores? How are people getting around this when they host 500 people like super earth? Do they get a large server and virtualize a machine with a large single core processor? It seems silly that java doesn't just by default take advantage of the power of the machine without first adding all of the advanced tweaking.
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    Well, my processor is FAST. I don't think it would be the limiting factor as far as players go on my server.
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    What processor do you have if you don't mind me asking?
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    I originally bought a Phenom X6 2.6GHz but sold it and bought a Phenom X4 3.5GHz factory speed (it comes with a bad fan)
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    So really in renting minecraft servers, the clock of the single core of the processor is the selling point. Now I only assume the larger servers have even more of a bigger processor to utilize. I see some servers hosting their maps on separate java server instances and I guess that is how they work around that because they can get each server to use 1/4th of the processing power (or whatever they use). This makes me even more want cross server teleportation but I would assume this will not happen (via vanilla client)
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    just wait for spout, it will be natively multithreaded.
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    Nathan C

    The big servers use the best server grade Intel CPU's on the market, that is how. The one's they use are 4 core Sandy Bridge based E3 processors.

    For example LegendaryCraft, which has around 250+ on at any given time uses a Intel E3-1290.

    You won't be able to host that much on a AMD processor, they are just too weak core for core, compared to Intel.
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    @moose517 I really don't like the use of mods much as my thought is that the more mods you have, the more chances to have issues of things breaking. I would like to see bukkit explore the possibilities of making their server platform take advantage of the hardware BUT that's the downfall of java for you.

    I guess I will be looking into more i5 sandy bridge dual core servers rather then dish the money out for a quad-core by wasting cores.
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    Sandy bridge at high clock speeds (i7-2600 or E3-1275). 3.4GHz per core is about the fastest you'll see, and it's fast enough for well over 100 slots, maybe over 200. And they of course store everything on a SSD/RAMdisk/RAID 10 array (with 10k RPM or 15k RPM drives). And they have ridiculous amounts of RAM. And a fast enough network to withstand both player traffic load and network attacks.
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    Daniel Heppner

    You can overclock an i5 to 5ghz. It's been done. :)
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    Yeah, and you can do the same with a i7 (I think they hit 4.9GHz on air alone).
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    I have an Intel Core I7-2600K
    Bought a €37 fan (Scythe Mugen Rev. B)
    flawlessly works at 4.5GHz.
    Intel Speedstap causes the CPU to clock at 1.6GHz when there is nothing to do, so it stays cool.
    When I get 100%CPU, it works at 8 threads at 4.5GHz
    I also clocked it to 4.6GHz, but when you go higher then 4.5 temperatures are raising very fast compared to the speed.
    I7-2600 Should get 5.2Ghz at 2 cores.

    4.5GHz - 100% load - 60 to 65°C - 4Cores 8 Threads
    4.6GHz - 100% load - 70 to 75°C - 4Cores 8 Threads

    For Java you just need one, fast core.

    In fact for java it doesn't matter if you get a I5-2500K or a I7-2600K
    I7 only adds HT and some other extra's, but I5 can reach 4.5GHz too
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    Yeah I was going to overclock the i5 safely enough to I can collocate the box at a datacenter. I personally haven't seen really any servers out there for rent that have i5s (Mostly i7s and Xeon).

    Have you had more heating issues with i5s rather then i7s for overclocking?
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    Why do people keep saying it's Java's fault for not utilizing more cores? This has nothing to do with Java, and everything with the Minecraft server not being a (well) multithreaded program. Java can utilize as many cores as it wants, if the application is written to do so. Take any old computer game (10 years or older) that's a .exe (written in C++ most likely). It will only utilize one core, no matter how many you have available.
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    I think there shouldn't be a real difference in temperature between a core I5 and a core I7 (If you turn HyperThreading off)
    Note that every CPU is different, so every CPU will have different limits.
    I noticed that Temperature began to Increase very steep from about 4.4 - 4.5GHz.
    Just make sure you DON'T overclock with Stock cooler, get a better cooler for less then €50, you'll be glad to have another cooler later.

    I'ld really recommend scythe mugen Rev.B., as it's keeping my CPU very cool (massive cooling block, about 11*13*15 cm with 120mm fan) Or liquid cooling.

    Note that you also have to watch for a good MotherBoard, as it has to keep track of the voltages, temperatures, speeds,... (I'm very satisfied of my Asus P67 Mobo)

    greets, hope this helped you a bit out on choosing your server setup.
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