Error when calling Rust from Python -

rust code:

#[no_mangle] use std::thread;  pub extern fn process() {     let handles: vec<_> = (0..10).map(|_| {         thread::spawn(|| {             let mut _x = 0;             _ in (0..5_000_001) {                 _x += 1             }         })     }).collect();      h in handles {         h.join().ok().expect("could not join thread!");     } } 

cargo.toml:

[package] name = "embed" version = "0.1.0" authors = ["hustlibraco <hustlibraco@gmail.com>"]  [lib] name = "embed" crate-type = ["dylib"] 

i build target/release/libembed.so, , create invoke.py in path：

from ctypes import cdll  lib = cdll.loadlibrary("target/release/libembed.so")  lib.process()  print("done!") 

executing, , error：

-bash-4.2# python invoke.py  traceback (most recent call last):   file "invoke.py", line 5, in <module>     lib.process()   file "/usr/lib64/python2.7/ctypes/__init__.py", line 373, in __getattr__     func = self.__getitem__(name)   file "/usr/lib64/python2.7/ctypes/__init__.py", line 378, in __getitem__     func = self._funcptr((name_or_ordinal, self)) attributeerror: target/release/libembed.so: undefined symbol: process 

how solve problem?

the #[no_mangle] goes on function, not on use.

#[no_mangle] pub extern fn process() { ... } 

for complete, working example, see the rust ffi omnibus "integers" example.