Closed
Description
After a few days studying Rust I have come to a road block with segmentation faults and other errors when running a simple program using an mpsc channel.
use std::thread;
use std::fs::File;
use std::io::{BufReader,BufRead};
pub fn main() {
let (tx, rx) = spmc::channel();
let mut handles = Vec::new();
for n in 0..3 {
let rx = rx.clone();
handles.push(thread::spawn(move || {
let mut word_count = 0;
loop {
let received = rx.recv();
match received {
Ok(_word) => {
word_count = word_count + 1;
},
Err(_e) => {
println!("Reader {}: {}, ", n, word_count);
break;
}
}
}
}));
}
handles.push(thread::spawn(move || {
let file = File::open("/usr/share/dict/british-english-insane").unwrap();
for line in BufReader::new(file).lines() {
let word = line.unwrap();
tx.send(word).unwrap();
}
}));
for handle in handles {
handle.join().unwrap();
}
println!("Done.");
}
This code should simply read all the lines of a Debian dictionary file and forward them to four threads. The expected result is like:
$ ./target/debug/threads-rust
Reader 2: 221485,
Reader 1: 217272,
Reader 0: 215518,
Done.
But mostly I get seg faults and other errors like so:
$ RUST_BACKTRACE=1 cargo run
Finished dev [unoptimized + debuginfo] target(s) in 0.02s
Running `target/debug/threads-rust`
munmap_chunk(): invalid pointer
Aborted (core dumped)
$ RUST_BACKTRACE=1 cargo run
Finished dev [unoptimized + debuginfo] target(s) in 0.02s
Running `target/debug/threads-rust`
Segmentation fault (core dumped)
$ RUST_BACKTRACE=1 cargo run
Finished dev [unoptimized + debuginfo] target(s) in 0.03s
Running `target/debug/threads-rust`
Reader 0: 654276,
Done.
$ RUST_BACKTRACE=1 cargo run
Finished dev [unoptimized + debuginfo] target(s) in 0.03s
Running `target/debug/threads-rust`
munmap_chunk(): invalid pointer
Aborted (core dumped)
$ RUST_BACKTRACE=1 cargo run
Finished dev [unoptimized + debuginfo] target(s) in 0.03s
Running `target/debug/threads-rust`
free(): invalid size
Aborted (core dumped)
$ RUST_BACKTRACE=1 cargo run
Finished dev [unoptimized + debuginfo] target(s) in 0.02s
Running `target/debug/threads-rust`
double free or corruption (out)
Aborted (core dumped)
I get similar errors on a Raspberry Pi 3.
$ uname -a
Linux monster 4.4.0-17134-Microsoft #706-Microsoft Mon Apr 01 18:13:00 PST 2019 x86_64 GNU/Linux
$ cargo --version
cargo 1.36.0 (c4fcfb725 2019-05-15)
$ rustc --version --verbose
rustc 1.36.0 (a53f9df32 2019-07-03)
binary: rustc
commit-hash: a53f9df32fbb0b5f4382caaad8f1a46f36ea887c
commit-date: 2019-07-03
host: x86_64-unknown-linux-gnu
release: 1.36.0
LLVM version: 8.0 $ cargo build
Compiling threads-rust v0.1.0 (/mnt/c/Users/zicog/conveqs/threads-rust)
Finished dev [unoptimized + debuginfo] target(s) in 1.72s