Calling Python function many times causes SEGV or hang.

[pandaman64]

🐛 Bug Reports

Repeatedly calling a Python function eventually fails at the 256'th call.
The process terminates with SEGV or sometimes hang indefinitely.

🌍 Environment

• Your operating system and version:
  Ubuntu 18.04.1 LTS on Windows Subsystem for Linux.
  I also noticed this bug on NixOS.

• Your python version:
  Python 3.6.6

• How did you install python (e.g. apt or pyenv)? Did you use a virtualenv?:
  Installed via apt

• Your rust version (rustc --version):
  rustc 1.32.0-nightly (6b9b97bd9 2018-11-15)

• Are you using the latest pyo3 version? Have you tried using latest master (replace version = "0.x.y" with git = "https://github.com/PyO3/pyo3")?
  0.5
  I confirmed the latest master still reproduces the bug.

💥 Reproducing

extern crate pyo3;

use pyo3::prelude::*;

#[test]
fn call_many_times() -> PyResult<()> {
    let guard = Python::acquire_gil();
    let py = guard.python();
    let math = py.import("math")?;
    let exp = math.get("exp")?;

    for i in 0..100000 {
        println!("{}", i);
        exp.call1((1.0_f64, ))?;
    }

    Ok(())
}

and cargo test -- --nocapture (I added --nocapture to find the limit).
You can get the code here: https://github.com/pandaman64/pyo3-test

Thank you

[kngwyu]

Maybe related to #271?

[kngwyu]

@pandaman64
Could you please test with #281?
It's a really serious and silly bug. Sorry 😓

[pandaman64]

@kngwyu It's working! Thanks!

[konstin]

Fixed by 0.5.1 then