Ergonomic, hermetic, user-friendly software build system for Python, Go, Java, Kotlin, Protobuf, Scala, Shell. Pants lets you fearlessly scale up your codebase!

Pants

so i dont need to discard the original PR

Well, unsurprisingly, BUILD file parsing is very expensive...

```fozzie:[~/src/pants][master]$ time ./pants
No goals specified.
Use `pants goals` to list goals.
Use `pants help` to get help.

real	0m1.250s
user	0m1.009s
sys	0m0.216s```

And according to the profile almost all that time is in parsing the bootstrap BUILD files

Which we only need because of `source_roots`

Didn't we once talk about expressing source roots some other way?

This will be in pants.ini -&gt; via @argfile for large source root sets like Square

<https://github.com/pantsbuild/pants/issues/2144>

But - Its very surprising to me that parsing via 1 bootstrap BUILD vs parsing pants.ini would be different by much

Yeah, I'm still not sure *why* parsing BUILD files is that expensive.

Yeah - source_root is a red herring here I'm sure

I mean we only have 8 such BUILD files in pantsbuild/pants

Well I don't think the issue is source_root per se

But if anything, BUILD files with targets in them should be far more expensive to parse, I see a lot of time spent in addressable resolution stuff (in profiles of ./pants list ::)

So on eta, not sure, I had that bug as 3rd in line in the chain derived from <https://github.com/pantsbuild/pants/issues/2141>

I have <https://github.com/pantsbuild/pants/issues/2151> next in queue then <https://github.com/pantsbuild/pants/issues/2156>

```fozzie:[~/src/pants][master]$ find . -name BUILD -type f | wc -l
     383
fozzie:[~/src/pants][master]$ time ./pants list &gt; /dev/null
&lt;snip some logs&gt;
real	0m4.148s
user	0m3.103s
sys	0m0.487s```

I think a lot of time is spent in parser setup overhead

I think <@U09S0QZM4> timed this stuff and found backend loading and argparse setup dominated the ~1s of startup time?