use std::thread::scope instead of scoped_threadpool

as it's easier to deal with TSAN false positives in the former API

as surfaced in PR 280 the current supression rules don't handle newer versions of the
scoped_threadpool crate

trying to update the supression rules related to scoped_threadpool in PR #282 revealed that the
supression rules are masking (hiding) real data races:
#282 (comment)

std::thread::scope requires less supression rules and does not mask real data races -- for instance,
the data race in the linked issue comment is not masked when using std::thread::scope

tradeoffs:
- pro: one less dev dependency
- pro: supressions file is simpler
- cons: std::thread::scope is only available on recent nightlies

Author: japaric

Cargo.toml

@@ -27,9 +27,6 @@ mpmc_large = []
 # This flag has no version guarantee, the `defmt` dependency can be updated in a patch release
 defmt-impl = ["defmt"]
 
-[target.'cfg(not(target_os = "none"))'.dev-dependencies]
-scoped_threadpool = "0.1.8"
-
 [target.thumbv6m-none-eabi.dependencies]
 atomic-polyfill = { version = "0.1.2", optional = true }
 

suppressions.txt

@@ -1,7 +1,2 @@
-# false positives in thread::spawn (?)
-race:*dealloc
-race:*drop_slow*
-race:__call_tls_dtors
-
-# false positives in scoped_threadpool (?)
-race:*drop*
+race:std::panic::catch_unwind
+race:std::thread::scope

tests/tsan.rs

@@ -1,11 +1,11 @@
+#![feature(scoped_threads)]
 #![deny(rust_2018_compatibility)]
 #![deny(rust_2018_idioms)]
 #![deny(warnings)]
 
 use std::{sync::mpsc, thread};
 
 use heapless::{mpmc::Q64, spsc};
-use scoped_threadpool::Pool;
 
 #[test]
 fn once() {
@@ -59,12 +59,12 @@ fn scoped() {
     {
         let (mut p, mut c) = rb.split();
 
-        Pool::new(2).scoped(move |scope| {
-            scope.execute(move || {
+        thread::scope(move |scope| {
+            scope.spawn(move || {
                 p.enqueue(1).unwrap();
             });
 
-            scope.execute(move || {
+            scope.spawn(move || {
                 c.dequeue().unwrap();
             });
         });
@@ -83,8 +83,8 @@ fn contention() {
     {
         let (mut p, mut c) = rb.split();
 
-        Pool::new(2).scoped(move |scope| {
-            scope.execute(move || {
+        thread::scope(move |scope| {
+            scope.spawn(move || {
                 let mut sum: u32 = 0;
 
                 for i in 0..(2 * N) {
@@ -95,7 +95,7 @@ fn contention() {
                 println!("producer: {}", sum);
             });
 
-            scope.execute(move || {
+            scope.spawn(move || {
                 let mut sum: u32 = 0;
 
                 for _ in 0..(2 * N) {
@@ -126,9 +126,9 @@ fn mpmc_contention() {
     static Q: Q64<u32> = Q64::new();
 
     let (s, r) = mpsc::channel();
-    Pool::new(2).scoped(|scope| {
+    thread::scope(|scope| {
         let s1 = s.clone();
-        scope.execute(move || {
+        scope.spawn(move || {
             let mut sum: u32 = 0;
 
             for i in 0..(16 * N) {
@@ -141,7 +141,7 @@ fn mpmc_contention() {
         });
 
         let s2 = s.clone();
-        scope.execute(move || {
+        scope.spawn(move || {
             let mut sum: u32 = 0;
 
             for _ in 0..(16 * N) {
@@ -178,14 +178,14 @@ fn unchecked() {
     {
         let (mut p, mut c) = rb.split();
 
-        Pool::new(2).scoped(move |scope| {
-            scope.execute(move || {
+        thread::scope(move |scope| {
+            scope.spawn(move || {
                 for _ in 0..N / 2 - 1 {
                     p.enqueue(2).unwrap();
                 }
             });
 
-            scope.execute(move || {
+            scope.spawn(move || {
                 let mut sum: usize = 0;
 
                 for _ in 0..N / 2 - 1 {
@@ -246,8 +246,8 @@ fn pool() {
 
     A::grow(unsafe { &mut M });
 
-    Pool::new(2).scoped(move |scope| {
-        scope.execute(move || {
+    thread::pool(move |scope| {
+        scope.spawn(move || {
             for _ in 0..N / 4 {
                 let a = A::alloc().unwrap();
                 let b = A::alloc().unwrap();
@@ -257,7 +257,7 @@ fn pool() {
             }
         });
 
-        scope.execute(move || {
+        scope.spawn(move || {
             for _ in 0..N / 2 {
                 let a = A::alloc().unwrap();
                 let a = a.init([2; 8]);