To avoid swap you should set swappiness to 1, not 0. 1 is a request (don't
swap if avoidable) whereas 0 is a demand (processes will be killed as OOM
instead of swapping.
However, I'm wondering why you are running such large heaps. Most of the ZK
heap is used for storage of the data in memory, and it's obvious from your
setup that this is a development instance. So if ZK is only being used for
that Kafka cluster you are testing, you can go with a smaller heap.
Also, for what reason are you running a 12 GB heap for Kafka? Even our
largest production clusters at LinkedIn are using a heap size of 6 GB right
now. You want to leave memory open for the OS to use for buffers and cache
in order to get better performance from consumers. You can see from that
output that it's trying to.
It really looks like you're just overloading your system. In which case
swapping is to be expected.
-Todd
On Aug 7, 2017 8:34 AM, "Gabriel Machado" <gmachado....@gmail.com> wrote:
Hi,
I have a 3 nodes cluster with 18 GB RAM and 2 GB swap.
Each node have the following JVMs (Xms=Xmx) :
- Zookeeper 2GB
- Kafka 12 GB
- Kafka mirror-maker DCa 1 GB
- Kafka mirror-maker DCb 1 GB
All th JVMs consume 16 GB. It leaves 2 GB for the OS (debian jessie 64
bits).
Why i have no swap free on these virtual machines ?
#free -m
total used free shared buffers cached
Mem: 18105 17940 164 0 38 6666
-/+ buffers/cache: 11235 6869
Swap: 2047 2045 2
I've read i should avoid jvm swapping.
What is the best way to do that ?
- modify swapiness threshold
- unmount all swap partition
- force the jvm to stay in memory with mlockall (
https://github.com/LucidWorks/mlockall-agent)
- Other solution
Gabriel.
