How to measure peak memory usage of a process tree?

By a process tree I mean the process and everything it executes in any way. I tried /usr/bin/time -v, but the results are entirely wrong. For example running a npm test in one of our projects with 14GiB free RAM and 8GiB of free swap results in OOM killer starting to kill my applications (most commonly a browser and IDE). time reports only 800MiB was used, even though the real memory consumption must have been very high, over 20GiB...