CODEWITHSUNDEEP
performancecontainersdockervirtualization
user1405309
user1405309

Reputation: 397

Docker Run Time Statistics ( Benchmarks)

I know there are lots of docker experts around but I spent considerable time to find out some facts and figure about Docker's run time performance, but unfortunately i could not get any concrete answer. Let me start with telling you my System's configuration:

(a) Running CentOS 6.5 on a machine having 48GB RAM, 1TB Disc and 12 Core CPUs. (b) I build up a Docker image which is having size almost 6.5GB

Below are questions if someone can answer for the benefit of readers:

(a) Now with the given configuration, question comes that how many containers I can run in parallel without break any functionality?

(b) Assume I have two Images each having size 3.5GB, then is it suggested to run multiple small size images or we get a good performance with big sized image?

(c) What is the best file systems option to use with Docker?

EDIT: more information

(d) Actually I'm trying to put many compilers inside a container and trying to give facility to users to compile their languages online. This tool is under development and will replace my existing website compileonlone.com. Things are going fine, I build up two images with few compilers in each. I'm able to run around 250 containers successfully and after that I start getting too many files opened. After 250 containers, my RAM is reaching somewhere 40GB and CPU utilization is around 50%,.

Main problem I'm facing is removal of the old containers. Because user will come and compile his code and then will go away, so I need to remove those container after certain period of time but when I'm trying to remove such stopped containers using docker rm -v, its slowing down main docker process and its almost hanging. I mean docker -d daemon which is listening at /var/run/docker.sock. Not sure if there is any other way around to clean these containers or I have a bug. Here is the detail of Docker:

  # docker info
    Containers: 1016
    Images: 41
    Storage Driver: devicemapper
     Pool Name: docker-0:20-258-pool
     Pool Blocksize: 64 Kb
     Data file: /var/lib/docker/devicemapper/devicemapper/data
     Metadata file: /var/lib/docker/devicemapper/devicemapper/metadata
     Data Space Used: 17820.7 Mb
     Data Space Total: 102400.0 Mb
     Metadata Space Used: 102.4 Mb
     Metadata Space Total: 2048.0 Mb
    Execution Driver: native-0.2
    Kernel Version: 3.17.2-1.el6.elrepo.x86_64
    Operating System: <unknown>
    WARNING: No swap limit support

If someone can help me on how to delete old containers in fastest way then it will be great. Simple shell script and all are not working. I already have tried like 

 #docker rm -v $(docker ps -a |grep Exited | awk '{print $1}')

but its completely slowing down main docker process and its unable to create new containers while this removal process is running.

Thanks for your time taken to answer these questions, which will help me as well as many others in going ahead with Docker.

Upvotes: 0

Views: 585

Answers (2)

user1405309
user1405309

Reputation: 397

After a lot R&D and discussing with many experts, I found a solution to delete containers with lightening speed. Its simple you have run your docker daemon with dm.blkdiscard=false option as follow.

docker -d --storage-opt dm.blkdiscard=false

By the way here is what I have developed. Here I need to create and delete containers with a high speed

http://codingground.tutorialspoint.com

Hope this will help many others.

Upvotes: 0

Bryan
Bryan

Reputation: 12190

a): A container is like a process. This question is like asking "how many processes can I run in parallel". It is not answerable without knowing what the processes are doing. Please add this information to your question.

b) Both 3.5GB and 6.5GB are very large for a Docker image. Best practice is to put one application in one container: if you have an application that size, then great. If not, maybe you have put your application's data into the image. This is not a good idea because the layered filesystem is slower than a regular filesystem, and you won't be wanting any of the features of layering or snapshotting on your transactional data.

The documentation on managing data explains how to mount regular disk so it is accessible from your containers.

Edit, after more information was supplied

d) Using up RAM implies the containers are still running. If there is some way within the logic of your site to know when a container is no longer needed you can docker kill it, then docker rm to remove the disk storage. Or docker rm -f does those two operations in one.

Upvotes: 1

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