How to use Docker to limit container resources

Problem Peeping

In the server, assuming that the IIS service deploys multiple sites, as long as one of the sites has a problem, for example, the CPU is 100% or the memory is full, then the other sites on this server will also crash. Similarly, when using containers, dozens of containers may run on a single host. Although the containers are isolated from each other, they use the same kernel, CPU, memory, disk and other hardware resources as the host. If container resources are not restricted, containers will affect each other.

Solution

Docker provides methods to limit memory, CPU or disk IO, which can limit the size and amount of hardware resources occupied by the container. We can limit the hardware resources of this container when we use docker create to create a container or docker run to run a container.

Memory Limits

The memory limit functions provided by Docker are as follows:

1. The memory and swap partition size that the container can use.

2. The core memory size of the container.

3. Swapping behavior of container virtual memory.

4. Soft limit of container memory.

5. Whether to kill containers that occupy too much memory.

6. Container Killing Priority

-m, --memory Memory limit, the format is a number plus a unit, the unit can be b, k, m, g. Minimum 4M
--memory-swap Total limit of memory + swap partition size. Same format as above. Required -m sets the soft limit on memory. Same format as above --oom-kill-disable Whether to prevent OOM killer from killing containers, not set by default --oom-score-adj The priority of the container being killed by OOM killer, the range is [-1000, 1000], the default is 0
--memory-swappiness is used to set the virtual memory control behavior of the container. The value is an integer between 0 and 100. --kernel-memory Kernel memory limit. Same format as above, minimum size is 4M

The user memory limit is to limit the size of the memory and swap partition that the container can use.
There are two intuitive rules to follow when using it:

The minimum parameter of the -m, --memory option is 4M.
--memory-swap is not the swap partition, but the total size of the memory plus the swap partition, so --memory-swap must be larger than -m, --memory.

CPU Limit

All options related to the docker run command and CPU limit are as follows:

--cpuset-cpus="" The set of CPUs allowed to be used, the value can be 0-3,0,1
-c, --cpu-shares=0 CPU share weight (relative weight)
cpu-period=0 limits the CPU CFS period, ranging from 100ms to 1s, i.e. [1000, 1000000]
--cpu-quota=0 Limit CPU CFS quota, must be no less than 1ms, i.e. >= 1000
--cpuset-mems="" Allow execution on memory nodes (MEMs), only valid for NUMA systems

The --cpuset-cpus is used to set the vCPU cores that the container can use. -c, --cpu-shares is used to set the relative proportion of CPU time that can be allocated to each container when multiple containers compete for the CPU. --cpu-period and --cpu-quata are used to set the absolute amount of CPU time a container can use.

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