RAM usage

[zetok]

Oxipng aec8e41

Used image: https://gist.github.com/zetok/1452501c644959325d45

pls fix?

[shssoichiro]

You're right, it looks like this is an issue when using high optimization levels (-o 6). oxipng is trying to spawn all the compression threads at once, and each thread uses memory. This isn't a problem with -o 2 (8 threads), but -o 6 spawns 648 threads at once.

I'll need to add a limit to the number of threads spawned at one time. Probably 1.5x the number of CPU cores.