Rust mpsc：：Sender 不能在线程之间共享

我认为通道的全部目的是在线程之间共享数据.我有这个密码，based on this example:

let tx_thread = tx.clone();
let ctx = self;
thread::spawn(|| {
    ...
    let result = ctx.method()
    tx_thread.send((String::from(result), someOtherString)).unwrap();
})

其中tx是mpsc::Sender<(String, String)>

error[E0277]: the trait bound `std::sync::mpsc::Sender<(std::string::String, std::string::String)>: std::marker::Sync` is not satisfied
   --> src/my_module/my_file.rs:137:9
    |
137 |         thread::spawn(|| {
    |         ^^^^^^^^^^^^^
    |
    = note: `std::sync::mpsc::Sender<(std::string::String, std::string::String)>` cannot be shared between threads safely
    = note: required because of the requirements on the impl of `std::marker::Send` for `&std::sync::mpsc::Sender<(std::string::String, std::string::String)>`
    = note: required because it appears within the type `[closure@src/my_module/my_file.rs:137:23: 153:10 res:&&str, ctx:&&my_module::my_submodule::Reader, tx_thread:&std::sync::mpsc::Sender<(std::string::String, std::string::String)>]`
    = note: required by `std::thread::spawn`

我不知道哪里出了错.除非我找错了地方，而我的问题实际上是我对let ctx = self;的使用？