cmemstat

A utility to retrieve memory stats of a running process from the memory cgroup.

How does that work? The tool starts itself as a child process and SIGSTOP itself. The parent wait4(2) for the child state to be stopped, then creates a cgroup using libcontainer and puts this init child process inside of it. Then the parent sends SIGCONT to the child that immediately executes the desired command, and finally, the parent periodically prints the cgroup memory stats. Almost nothing is performed by the child between SIGSTOP and SIGCONT so the memory measurement by the cgroup should be accurately associated to the target command.

Installation

go install github.com/mtardy/cmemstat@latest

Usage

cmemstat [option]... program [programoption]...

For example, to retrieve the memory usage of sleep 3 with the --debug option refreshing the stats every 400ms:

cmemstat --debug --refresh 400ms sleep 3

Or with default options:

cmemstat sleep 3