Limiting java application's memory and cpu usage

Question

Say, "run myApp.jar with cpu=800 and memory=1024"

Ive been doing java programming for many years and it is an embarrasment to ask this question. I don't even know whether this is possible or not. And if so, how?

What I just want know is if it is possible to set a java program's maximum memory and cpu usage. I suddenly thought of this because of I recently started developing mobile apps. I want to know how the app will behave on the device which has very limited memory and processor.

I saw physics engines with demo apps that run on the browser or I can execute on my PC. What if I run them on a mobile device? Will the performance be the same? Rather than developing a sample mobile app to test the library's performance, I'd rather run it with a specific cpu and memory using my PC first.

I tried googling by the way... all i found was monitoring and performance tuning. I may be using wrong keywords.

Answer 1

you can limit memory usage by -Xmx option and you can limit CPU usage by setting priority of the process and/or CPU affinity.

Answer 2

The JVM has no control over CPU usage nor priority.

JVM has control over max/min Memory usage.

There is a workaround. It is possible to run each JVM in a separate [Docker container][1]. And control the resource (Memory, CPU, Network, IO) allocation for each container. That is exactly the added value of the Docker containers.

[1]: The JVM has no control over CPU usage nor priority. Yet you can run each JVM in a separate Docker container. And control the resource allocation foreach container. That is exactly the added value of the Docker containers.

Answer 3

Linux:

taskset -a -c 0,1,2,3 <program>

Run a program and its child threads only on cores 0, 1, 2, and 3.

Answer 4

Docker offers up resource management options for limiting the cpu access for running docker containers. Have a look at the CFS scheduler options available with docker run from Limit a container's resources in the Docker documentation, such as:

• --cpus=<value> - Specify how much of the available CPU resources a container can use. For instance, if the host machine has two CPUs and you set --cpus="1.5", the container is guaranteed at most one and a half of the CPUs. This is the equivalent of setting --cpu-period="100000" and --cpu-quota="150000". Available in Docker 1.13 and higher.
• --cpuset-cpus - Limit the specific CPUs or cores a container can use. A comma-separated list or hyphen-separated range of CPUs a container can use, if you have more than one CPU. The first CPU is numbered 0. A valid value might be 0-3 (to use the first, second, third, and fourth CPU) or 1,3 (to use the second and fourth CPU).

These options are also available via docker-compose, when deploying a Docker swarm / stack, as mentioned in Compose file version 3 reference under resources:

version: '3'
services:
  redis:
    image: redis:alpine
    deploy:
      resources:
        limits:
          cpus: '0.50'
          memory: 50M
        reservations:
          cpus: '0.25'
          memory: 20M```

Note: that the legacy resource options in docker compose v2 are now limited to stacks in the migration to v3.