Open
Description
Initially reported sqlpage/SQLPage#435
When making streaming responses and activating middleware::Compress, the compression seems to buffer content indefinitely, without ever flushing the streaming data when it's small enough.
Here is an example demonstrating the problem
use actix_web::{
get, middleware,
web::{self, Bytes},
App, HttpResponse, HttpServer,
};
use futures::stream::{self, StreamExt};
use std::time::Duration;
use tokio::time::sleep;
#[get("/")]
async fn index() -> HttpResponse {
let stream = stream::once(async {
let initial_content = r#"
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Streaming HTML Example</title>
</head>
<body>
<div>This content appears immediately</div>
"#;
Ok::<_, std::io::Error>(Bytes::from(initial_content))
})
.chain(stream::once(async {
sleep(Duration::from_secs(5)).await;
let delayed_content = r#"
<div>This content appears after 5 seconds</div>
</body>
</html>
"#;
Ok::<_, std::io::Error>(Bytes::from(delayed_content))
}));
HttpResponse::Ok()
.content_type("text/html; charset=utf-8")
.streaming(stream)
}
#[actix_web::main]
async fn main() -> std::io::Result<()> {
HttpServer::new(|| {
App::new()
.service(
web::scope("/compressed")
.wrap(middleware::Compress::default())
.service(index),
)
.service(index)
})
.bind("127.0.0.1:8080")?
.run()
.await
}Expected Behavior
- When visiting I should see
This content appears immediatelyimmediateley, and then after 5 secondsThis content appears after 5 seconds - When visiting http://localhost:8080/compressed/ the behavior should be the same, or as close as possible.
Current Behavior
- When visiting http://localhost:8080/compressed/ the page stays blank for five seconds, then displays
This content appears immediatelyandThis content appears after 5 secondsat the same time.
Possible Solution
The compression middleware should flush the writer object after a few milliseconds without new input data, to avoid indefinitely retaining data in memory on the server when it could actually already be rendered on the client.
It's possible to retain data in memory for a few milliseconds to ensure good compression ratios, but actix shouldn't keep streaming data in memory for multiple seconds.
Context
We are trying to integrate easy native loading spinners without javascript in SQLPage
Your Environment
- Actix Web Version: 4.8.0