@swift-ci create

Comment by Jascha Burmeister (JIRA)

Another example. Memory is growing over time and only gets freed after completing the loop.

import Foundation


let url = URL(string: "https://upload.wikimedia.org/wikipedia/commons/thumb/c/c2/Italian_States-Piacenza_1626_2_Doppie.jpg/2880px-Italian_States-Piacenza_1626_2_Doppie.jpg")!


for i in 1...200 {
    autoreleasepool {
        print(i)
        URLSession.shared.dataTask(with: url) { _, _, _ in


        }.resume()
        sleep(1)
    }
}

RunLoop.main.run()

Comment by Jascha Burmeister (JIRA)

I decided to rewrite my application in Rust and surprisingly had the same memory issue. Same code runs fine on Linux. There seems to be a memory leak down the network request stack.

use reqwest;
use std::{thread::sleep, time::Duration};

fn main() {
    // memory grows around 0.1 MB every 10 seconds
    loop {
        let _ = reqwest::blocking::get("https://jsonplaceholder.typicode.com/posts");
        sleep(Duration::from_millis(10));
    }
}

Here's the message I received:

The session needs to be invalidated.

You can check out: https://developer.apple.com/documentation/foundation/urlsession

Important

The session object keeps a strong reference to the delegate until your app exits or explicitly invalidates the session. If you don’t invalidate the session, your app leaks memory until the app terminates.

From what I understand based on the discussion in this reddit thread, the above doesn't quite answer how to fix the leak, since there is no delegate in the example. https://www.reddit.com/r/swift/comments/ms5orj/possibly_memory_leak_in_macos_network_request/

However, since this issue is related to the networking stack and not the open source toolchain (Swift, LLDB, SourceKit etc.), and a separate Feedback has been filed (FB9076036), I'm going to leave this as Resolved instead of reopening it.