PtyProcess.spawn (and thus pexpect) slowdown in close() loop about ptyprocess HOT 2 OPEN

Hmm, it's annoying that closerange isn't implemented more efficiently, but I guess there's not much I can do about that.

The difficulty with using subprocess is that at the heart of ptyprocess, we call forkpty() rather than fork(). That's a different call all the way down to libc. There is a fallback implementation using fork(), with comments indicating it's for Solaris, but I don't know how well-tested it is, and I'm not confident in my abilities to write properly bulletproof low-level system code like this.

ptyprocess is also (as a component pulled out of pexpect), old code which has, over the years, attempted to support many platforms. I'm reluctant to make major changes to it, because I don't know all the platforms and use cases where it's running in the wild. So maybe you're better off writing a new module under a different name to do the same thing without all the legacy concerns. I'm happy to link to it from the docs.

from ptyprocess.

@takluyver well, perhaps you can do something like this instead: python/cpython@5626fff

The good news is:

0. it's already written, just need to be adopted to your codebase;
1. it's a small change, relatively easy to review;
2. this is Linux-only and won't break any other platform;
3. it falls back to the existing implementation in case it's not working;
4. it will speed up your software considerably under Docker on Linux.

from ptyprocess.