pymodule: don't call PyEval_InitThreads

CHANGELOG.md

@@ -45,6 +45,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Deprecate `#[name = "..."]` attributes in favor of `#[pyo3(name = "...")]`. [#1567](https://github.com/PyO3/pyo3/pull/1567)
 - Reduce LLVM line counts to improve compilation times. [#1604](https://github.com/PyO3/pyo3/pull/1604)
 - Deprecate string-literal second argument to `#[pyfn(m, "name")]`. [#1610](https://github.com/PyO3/pyo3/pull/1610)
+- No longer call `PyEval_InitThreads()` in `#[pymodule]` init code. [#1630](https://github.com/PyO3/pyo3/pull/1630)
 
 ### Removed
 - Remove deprecated exception names `BaseException` etc. [#1426](https://github.com/PyO3/pyo3/pull/1426)

src/derive_utils.rs

@@ -315,12 +315,6 @@ impl ModuleDef {
         py: Python,
         initializer: impl Fn(Python, &PyModule) -> PyResult<()>,
     ) -> PyResult<*mut ffi::PyObject> {
-        #[cfg(py_sys_config = "WITH_THREAD")]
-        // > Changed in version 3.7: This function is now called by Py_Initialize(), so you don’t have
-        // > to call it yourself anymore.
-        #[cfg(not(Py_3_7))]
-        ffi::PyEval_InitThreads();
-
         let module =
             unsafe { py.from_owned_ptr_or_err::<PyModule>(ffi::PyModule_Create(self.0.get()))? };
         initializer(py, module)?;