limit parallel threads by waiting for the first thread to complete

src/main.rs

@@ -654,12 +654,27 @@ impl std::fmt::Display for ConvertError{
 }
 impl std::error::Error for ConvertError{}
 
+type MapThread=std::thread::JoinHandle<Result<(),ConvertError>>;
+
 fn convert_to_snf(pathlist:Vec<std::path::PathBuf>,output_folder:PathBuf)->AResult<()>{
+	let n_paths=pathlist.len();
 	let start = std::time::Instant::now();
-	let mut threads:Vec<std::thread::JoinHandle<Result<(),ConvertError>>>=Vec::new();
+	let mut threads:std::collections::VecDeque<MapThread>=std::collections::VecDeque::new();
+	let mut i=0;
+	let mut join_thread=|thread:MapThread|{
+		i+=1;
+		if let Err(e)=thread.join(){
+			println!("thread error: {:?}",e);
+		}else{
+			println!("{}/{}",i,n_paths);
+		}
+	};
 	for path in pathlist{
+		if 32<=threads.len(){
+			join_thread(threads.pop_front().unwrap());
+		}
 		let output_folder=output_folder.clone();
-		threads.push(std::thread::spawn(move ||{
+		threads.push_back(std::thread::spawn(move ||{
 			let dom=strafesnet_rbx_loader::read(
 				std::fs::File::open(path.as_path())
 				.map_err(ConvertError::IO)?
@@ -703,15 +718,8 @@ fn convert_to_snf(pathlist:Vec<std::path::PathBuf>,output_folder:PathBuf)->AResu
 		}));
 	}
 
-	let mut i=0;
-	let n_threads=threads.len();
 	for thread in threads{
-		i+=1;
+		join_thread(thread);
-		if let Err(e)=thread.join(){
-			println!("thread error: {:?}",e);
-		}else{
-			println!("{}/{}",i,n_threads);
-		}
 	}
 	println!("{:?}", start.elapsed());
 	Ok(())