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pause vs stop in docker

I am trying to understand what is the difference between the commands docker stop ContainerID and docker pause ContainerID. According to this page both of them are used to pause an existing Docker container.

Solution

  • What is the difference between docker stop and docker pause?

    • docker stop: Send SIGTERM(termination signal), and if needed SIGKILL(kill signal)
    • docker pause: Send SIGSTOP(pause signal)

    • SIGTERM: The default behavior is to terminate the process, but it also can be caught or ignored. The intention is to kill the process, gracefully or not, but first give it a chance to clean up.

    • SIGKILL: The only behavior is to kill the process, immediately. As the process cannot catch the signal, it cannot clean up; thus, this is a signal of last resort.

    • SIGSTOP: The only behavior is to pause the process; the signal cannot be caught or ignored. The shell uses pausing (and its counterpart, resuming via SIGCONT) to implement job control

    When to use docker stop and docker pause?

    • docker stop: When you wish to clear up memory or delete all of the processes' -cached- data. Simply put, you no longer care about the processes in the container and are comfortable with killing them.
    • docker pause: When you only want to suspend the processes in the container; you do not want them to lose data or state.

    Example:

    Consider a container with a counter. Assume the counter has reached 3000. Running docker stop will cause the counter to lose its value and you will be unable to retrieve it. Using docker pause, on the other hand, will maintain the counter state and value.

    Hope it's clear now!