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Date: Mon, 13 Jun 2011 13:40:22 -0400
Message-ID: <BANLkTi=LFesj+yZQJA6CiT2PSD9VC01uUA@mail.gmail.com>
Subject: Re: RE: swap
From: Camille Fournier <camille@apache.org>
To: user@zookeeper.apache.org
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To add on to this, you know how much memory your vm can allocate, you know
how much memory your system has. You shouldn't allocate more memory to the
zk vm than the system has minus a percentage for overhead. If you don't hav=
e
enough space on the machine to run zk without swapping, the machine is too
small for your use case.
On Jun 13, 2011 9:38 AM, "Fournier, Camille F." <Camille.Fournier@gs.com>
wrote:
> My advice is to turn off disk swap completely if you are using the machin=
e
to run only ZK, or any app which should always have its entire heap in
memory. Disk swapping by java heaps is very, very bad for apps with
performance driven by caching all state. You will need to leave some amount
of memory for OS overhead (it's been too long since I did that analysis but
I would make sure it is at least in the neighborhood of 10% of the total
available memory).
>
> C
>
> -----Original Message-----
> From: Donna Li [mailto:donna.li@utstar.com]
> Sent: Monday, June 13, 2011 3:09 AM
> To: user@zookeeper.apache.org
> Subject: =B4=F0=B8=B4: swap
>
> Thanks ted.
> I want to know the relation between java heap size and swap. Zookeeper
physical memory is enough, but swap is used by 302064k. Should I increase m=
y
java heap size or decrease my java heap size?
>
> -----=D3=CA=BC=FE=D4=AD=BC=FE-----
> =B7=A2=BC=FE=C8=CB: Ted Dunning [mailto:ted.dunning@gmail.com]
> =B7=A2=CB=CD=CA=B1=BC=E4: 2011=C4=EA6=D4=C213=C8=D5 14:33
> =CA=D5=BC=FE=C8=CB: user@zookeeper.apache.org
> =D6=F7=CC=E2: Re: swap
>
> This sounds like a question with a story behind it.
>
> Do you mean that your ZK server filled up all of memory and caused the
> machine to start swapping?
>
> If that is your problem, then there really is no fix other than to not
> do that. The reason is that Zookeeper is memory based so if you don't
> have enough memory, either because you are over-filling Zookeeper or
> have insufficient memory, then things aren't going to work.
>
> Turning off swap may be one of the worst things to do in this case
> since the machine will tend to fail harder instead of just getting
> very slow. That can make recovery more difficult.
>
> On Mon, Jun 13, 2011 at 5:52 AM, Donna Li <donna.li@utstar.com> wrote:
>>
>> Hi, all:
>>        How to avoid swap on zookeeper server?
>>
>> Best Regards
>> Donna li
>>

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