Hitting OOM error when building large pest file

[negator]

I have a large-ish pest file (~ 2600) lines with rules that include large numbers of alternations. When compiling this, the rustc process consumes a peak of ~35GB. I assume this has something to do with the optimization step?

Attaching the file for reference

entity.pest.zip

[dragostis]

I've managed to compile this with less than 200MBs used by rustc. What version of Rust are you using?

[negator]

Im compiling on a Mac:

stable-x86_64-apple-darwin (default)
rustc 1.20.0 (f3d6973f4 2017-08-27)

I've attached a sample project, including a Cargo.toml file with no optimizations. Running cargo build and examining the Acitivity Monitor, shows memory usage climb to more than 30GB.

pest_test.zip

[negator]

Note this is compressed memory usage. Actual memory usage hits 3-4GB

[dragostis]

cargo build ran with around 300-400MBs:

Finished dev [unoptimized + debuginfo] target(s) in 29.8 secs

UPDATE: It seems like there's a problem on stable. I'm getting OOM on stable too, but not on nightly, or beta.

[dragostis]

I took a look over some recently closed issues in rustc, but I wasn't able to where the issue stems from. I would recommend using beta (1.21) until the 12th of October when 1.21 launches. I'll try to look into this soon.

[Victor-Savu]

Would it make sense to report a bug on the compiler so that it is documented there as well? Especially if the problem was fixed by chance, it points to a potential regression later on.

[dragostis]

@Victor-Savu Definitely. I've just pushed a feature not so long ago. I'll try to handle this next. (see exactly where the regression might be)

[negator]

Looks like it was a bug in the rust compiler, rust-lang/rust#43613.

Probably isn't worth looking into further but good to note for reference.

I'Ill use nightly until rust 1.21 is released. Thanks for the quick responses!

[dragostis]

Thanks for finding the issue. I'll close this, since the next release of Rust is due to arrive soon anyway.