I am solving a problem for the website Exercism in rust, where I basically try to concurrently count how many times different letters occur in some text. I am doing this by passing hashmaps between threads, and somehow am in some kind of infinite loop. I think the issue is in my handling of the receiver, but I really don't know. Please help.
use std::collections::HashMap;
use std::thread;
use std::sync::mpsc;
use std::str;
pub fn frequency(input: &[&str], worker_count: usize) -> HashMap<char, usize> {
// Empty case
if input.is_empty() {
return HashMap::new();
}
// Flatten input, set workload for each thread, create hashmap to catch results
let mut flat_input = input.join("");
let workload = input.len() / worker_count;
let mut final_map: HashMap<char, usize> = HashMap::new();
let (tx, rx) = mpsc::channel();
for _i in 0..worker_count {
let task = flat_input.split_off(flat_input.len() - workload);
let tx_clone = mpsc::Sender::clone(&tx);
// Separate threads ---------------------------------------------
thread::spawn(move || {
let mut partial_map: HashMap<char, usize> = HashMap::new();
for letter in task.chars() {
match partial_map.remove(&letter) {
Some(count) => {
partial_map.insert(letter, count + 1);
},
None => {
partial_map.insert(letter, 1);
}
}
}
tx_clone.send(partial_map).expect("Didn't work fool");
});
// --------------------------------------------------
}
// iterate through the returned hashmaps to update the final map
for received in rx {
for (key, value) in received {
match final_map.remove(&key) {
Some(count) => {
final_map.insert(key, count + value);
},
None => {
final_map.insert(key, value);
}
}
}
}
return final_map;
}
question from:
https://stackoverflow.com/questions/65649189/channels-for-passing-hashmap-between-threads-stuck-in-loop-rust 与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…