virtualenv VS zsh-bench

For more information visit: virtualenv documentation.

Python's venv module is officially recommended for creating virtual environments since Python 3.5 comes packaged with your Python installation. While there still are additional older tools available, such as conda and virtualenv, if you are new to virtual environments, it is best to use venv now.

Despite these attractive attributes, many developers I've come across don't prefer Fish shell, primarily due to integration gaps with tools like Python's virtualenv. So, in this article, I'm offering a simple solution for automatic virtualenv activation for Fish shell, steering clear of resource-intensive frameworks like oh-my-fish that often slow down the shell.

`virtualenv` still exists and is still actively developed. It's true that Python 3 ships with `venv` but I think `virtualenv` offers some additional features.

https://github.com/pypa/virtualenv

virtualenv is a tool that creates an isolated Python environment for each of your projects.

Python is the chosen language for this tutorial and as you can guess some precautions should be done to make sure that the environment is setup correctly and the main OS I'll use is Ubuntu(a Linux distro) virtual environment is a tool that helps you to isolate your code from the rest of the system. It is a good idea to create a virtual environment for your project.

$ curl -O https://github.com/pypa/virtualenv/raw/master/virtualenv.py$ python virtualenv.py my_new_env$ . my_new_env/bin/activate(my_new_env)$ pip install ... Or something entirely different?

I've been using Fish for years and spend my entire day working with Python. Python's virtualenv has an `activate.fish` command, I've never had any problems with it. Additionally, we have a ton of internal tooling built in a fabfile, so I've written a couple of snippets of fish that automatically activate that .venv (Poetry managed) whenever I cd into a directory that has one, and also expands a bunch of env vars into the shell session. I've also got this feature request in on the virtualenv repo in the hope that one day we can have activate.fish emit an event - https://github.com/pypa/virtualenv/issues/1456

We of cause, like all good developers do, put the error message online and look for clues, we quickly found a GitHub issue and boi, we are not the only souls that got crushed by a "timely" release of virtualenv just a few hours before us. Since the lastest version of virtualenv got installed every time we create the CI build job on Travis, it fails even we have done nothing. Of cause we didn't point fingers at other maintainers, they are just as hardworking as us and it's human to make mistakes. We are faced with 2 options, roll back to the previous release or wait for the patch of virtualenv to get released. As the devs of virtualenv did a lighting fast patch, we have chosen option 2.

Someone's made a benchmarking system for zsh: https://github.com/romkatv/zsh-bench#premade-configs

Of course, their config is the best according to the benchmark (and ohmyzsh is the slowest option), but DIY configs are also covered, particularly possible performance optimizations.

Unfortunately, running exit is not a great strategy for running benchmarks. For zsh specifically, plugin managers are optimized for fast exit.

romkatv did a great write-up and benchmark within the context of zsh[0]. It's a great read.

[0] https://github.com/romkatv/zsh-bench#how-not-to-benchmark

Given the addition of async rendering in the latest release of spaceship, I wasn't sure whether I should include performance in the list of features found in powerlevel10kbut but not in spaceship. I used zsh-bench to benchmark powerlevel10k on my laptop running on battery (I'm writing this on a train) with a config that makes powerlevel10k looks similar to spaceship. I simply ran p10k configure and chose what looked most similar: Lean Style, UNICODE, 256 colors, two lines, etc. Here are the benchmark results:

Obligatory link since you are engaging in profiling interactive zsh: https://github.com/romkatv/zsh-bench.

1.) It's fast. Like, really fast. 1.) It supports deferred loading via zsh-defer 1.) It supports local plugins as well as ones hosted via a git provider (aka: GitHub, GitLab, BitBucket, etc) 1.) The codebase is simple and easy to understand and contribute to 1.) It supports git branches (with tag/shas on the roadmap) 1.) It supports partial plugin loading such as loading Oh-My-Zsh plugins and Prezto modules without loading the whole framework. 1.) There's an easy migration path from legacy plugin managers like Antigen/Antibody. 1.) Plugins are managed via a simple plugins file that makes it easy to share your config with others. 1.) And lots more

In any case, slow zsh startup is always caused by whatever you put in zsh startup files and it's always possible to reduce zsh startup to imperceptible levels without sacrificing any functionality by editing said startup files. There is a bit of info on interactive zsh performance at https://github.com/romkatv/zsh-bench.

Why is this a good thing? Is this a proxy for performance? If so, you can measure performance directly with zsh-bench. This way you can describe the advantage in terms that have real value to end users. For example, you can say that the first prompt appears N milliseconds faster when using Zpy than if you were using something-else.