Speeding up my zsh prompt: Part 1
I’m a big fan of the z shell. I use it with the spaceship prompt.
I use zplug for plugin management.
Right now, it takes an uncomfortable amount of time to load up the prompt on terminal emulator launch, which is annoying for me since I like everything to be snappy, at least on the command line.
Overview of my zshrc
It’s pretty basic, boasts of a zplug installation for plugin management
and some attendant plugins.
The culprit could be any one of those.
Diagnosing
The first step in any speed based diagnoses is profiling. I need to convert the subjective speed rush into tangible numbers and then try to reduce the load time by an order of magnitude
Using bash inbuilt utility time
time zsh -i -c exit
zsh -i -c exit 0.17s user 0.17s system 86% cpu 0.402 total
It returned 0.17 seconds, and a long 0.17 seconds it is.
This happens when the said command is launched from zsh itself. Trying to launch it from bash
real 0m0.892s
user 0m0.579s
sys 0m0.278s
user time is 0.578s which is a lot again. Apparently it’s even higher because zsh takes time to load the first time. Debugging it is gonna be interesting.
Profiling
zsh contains a profiling tool called zprof bundled. Let’s figure
out how to inject it.
You just use it this way it appears in my zshrc:
zmodload zsh/zprof
<rest of my zshrc>
zprof
Launched zshell and here’s an extract from the output:
num calls time self name
-----------------------------------------------------------------------------------
1) 2 346.23 173.12 52.57% 346.23 173.12 52.57% compdump
2) 4 574.15 143.54 87.17% 116.10 29.02 17.63% compinit
3) 1825 75.05 0.04 11.39% 75.05 0.04 11.39% compdef
4) 6 36.77 6.13 5.58% 36.77 6.13 5.58% compaudit
5) 1 12.63 12.63 1.92% 12.58 12.58 1.91% __zplug::base::base::git_version
6) 1 9.53 9.53 1.45% 9.53 9.53 1.45% __zplug::utils::awk::available
7) 4 10.50 2.62 1.59% 7.63 1.91 1.16% __zplug::core::load::as_plugin
8) 1 12.50 12.50 1.90% 6.27 6.27 0.95% __check__
9) 4 5.87 1.47 0.89% 5.87 1.47 0.89% __zplug::sources::github::check
10) 1 43.06 43.06 6.54% 5.24 5.24 0.80% __zplug::core::core::prepare
11) 4 6.49 1.62 0.98% 5.15 1.29 0.78% __zplug::core::sources::call
12) 2 4.65 2.32 0.71% 4.65 2.32 0.71% __zplug::io::file::rm_touch
13) 4 9.82 2.46 1.49% 3.34 0.83 0.51% __zplug::core::sources::use_default
14) 3 4.29 1.43 0.65% 3.16 1.05 0.48% __zplug::core::core::get_interfaces
15) 4 12.40 3.10 1.88% 2.55 0.64 0.39% __zplug::core::add::to_zplugs
16) 4 2.39 0.60 0.36% 2.39 0.60 0.36% __zplug::job::handle::flock
17) 1 1.90 1.90 0.29% 1.90 1.90 0.29% __zplug::core::cache::diff
18) 5 1.69 0.34 0.26% 1.69 0.34 0.26% github.zsh
19) 7 7.45 1.06 1.13% 1.57 0.22 0.24% __zplug::base
20) 1 5.82 5.82 0.88% 1.51 1.51 0.23% __zplug::core::core::variable
21) 29 1.13 0.04 0.17% 1.13 0.04 0.17% regexp-replace
22) 1 0.76 0.76 0.12% 0.76 0.76 0.12% colors
23) 1 0.44 0.44 0.07% 0.44 0.44 0.07% git.zsh
24) 1 0.44 0.44 0.07% 0.44 0.44 0.07% handle.zsh
25) 1 0.39 0.39 0.06% 0.39 0.39 0.06% core.zsh
26) 1 31.61 31.61 4.80% 0.36 0.36 0.05% __zplug::core::load::from_cache
27) 1 0.34 0.34 0.05% 0.34 0.34 0.05% theme.zsh
28) 6 0.28 0.05 0.04% 0.28 0.05 0.04% add-zsh-hook
29) 1 0.28 0.28 0.04% 0.28 0.28 0.04% cache.zsh
30) 1 0.27 0.27 0.04% 0.27 0.27 0.04% load.zsh
31) 1 0.26 0.26 0.04% 0.26 0.26 0.04% oh-my-zsh.zsh
32) 2 0.25 0.13 0.04% 0.25 0.13 0.04% prezto.zsh
33) 1 0.23 0.23 0.04% 0.23 0.23 0.04% shell.zsh
Looks like compdump and compinit are taking up most of the initialization time.
Don’t exactly remember what they are.. gonna have to reinvestigate zshrc
This also gives me an opportunity to clean up my zshrc.
After a brief research I come across this gist that recommends checking a .zcompdump file
only once a day for improved performance.
After incorporating this to my zshrc, I try my tests again. And the results are in:
With bash:
real 0m0.449s
user 0m0.190s
sys 0m0.217s
Looks like the init time has almost halved for user. Good enough for me I guess.
However the profiling tells another story.
num calls time self name
-----------------------------------------------------------------------------------
1) 3 426.16 142.05 54.35% 426.16 142.05 54.35% compdump
2) 4 697.40 174.35 88.95% 137.28 34.32 17.51% compinit
3) 2312 99.99 0.04 12.75% 99.99 0.04 12.75% compdef
4) 6 34.01 5.67 4.34% 34.01 5.67 4.34% compaudit
5) 1 12.43 12.43 1.59% 12.39 12.39 1.58% __zplug::base::base::git_version
6) 1 8.87 8.87 1.13% 8.87 8.87 1.13% __zplug::utils::awk::available
7) 6 11.56 1.93 1.47% 7.94 1.32 1.01% __zplug::core::load::as_plugin
8) 1 15.24 15.24 1.94% 7.73 7.73 0.99% __check__
9) 5 7.10 1.42 0.91% 7.10 1.42 0.91% __zplug::sources::github::check
10) 5 8.41 1.68 1.07% 6.70 1.34 0.85% __zplug::core::sources::call
11) 1 42.80 42.80 5.46% 6.47 6.47 0.82% __zplug::core::core::prepare
12) 5 12.70 2.54 1.62% 4.29 0.86 0.55% __zplug::core::sources::use_default
13) 5 16.08 3.22 2.05% 3.34 0.67 0.43% __zplug::core::add::to_zplugs
14) 3 4.41 1.47 0.56% 3.19 1.06 0.41% __zplug::core::core::get_interfaces
15) 6 1.99 0.33 0.25% 1.99 0.33 0.25% github.zsh
16) 1 1.97 1.97 0.25% 1.97 1.97 0.25% __zplug::core::cache::diff
The time taken by compinit has increased from 574.15 ms to 697 ms and it doesn’t feel snappy either.
The plot thickens. To be continued..
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