`cargo run` with a huge number of arguments doesn’t work

[ariasuni]

I have a folder with 16’000 files. When I run cargo run folder/*, Cargo seems blocked and takes a lot of RAM. However, when I run the exec directly (e.g. ./target/debug/exec) it works perfectly well.

[alexcrichton]

Thanks for the report! If possible, could you get a snapshot/profile of where the time is being spent in Cargo?

[ariasuni]

I used callgrind, waited 20 seconds before terminating the program with Ctrl+c, and I got that: https://gist.github.com/ariasuni/26822c6dc6121167a5b226c636779582

[alexcrichton]

Thanks! I've reported upstream at docopt/docopt.rs#207

[Eh2406]

with #5152 we are using clap. Move to close?

[ariasuni]

ripgrep, which is using Clap, don’t choke with twice as much as arguments on the command line.

[matklad]

@ariasuni could you verify just in case that Cargo itself works ok with huge number of arguments now? The fact that we”ve switched to clap does not mean we use it 100% correct :)

[ariasuni]

I just compiled master branch of cargo and ran it with cargo run --release <39498 arguments> and it said error: no such subcommand in a very few seconds, so it’s 100% confirmed now. :)