[weavie]

A few years ago I worked on a Solaris box that would lock the whole machine up whenever I grepped through the log files. Like it wouldn't just be slow, the web server that was running on it would literally stop serving requests while it was grepping.

I never worked out how that could be happening.

[burntsushi]

My best guess is your grep search was saturating I/O bandwidth, which slowed everything else to a crawl.

Another possibility is that your grep search was hogging up your system's memory. That might make it swap. On my systems which do not have swap enabled but do have overcommit enabled, I experience out-of-memory conditions as my system essentially freezing for some period of time until Linux's OOM-killer kicks in and kills the offending process.

I would say the first is more likely than the second. In order for grep to hog up memory, you need to be searching some pretty specific kinds of files. A simple log file probably won't do it. But... a big binary file? Sure:

    grep -a burntsushi /proc/self/pagemap

Don't try that one at home kids. You've been warned. (ripgrep should suffer the same fate.)

(There are other reasons for a system to lock up, but the above two are the ones that are pretty common for me. Well, in the past anyway. Now my machines have oodles of RAM and lots of I/O bandwidth.)