http2.request is downloading data with a very slow speed, if the network latency is significant

[segfault-bilibili]

Node.js Version

v22.5.1

NPM Version

v10.8.2

Operating System

Linux VPS 6.8.0-38-generic #38-Ubuntu SMP PREEMPT_DYNAMIC Fri Jun 7 15:25:01 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

Subsystem

http2

Description

As the title suggests, the downloading speed could be around 200-300KB/s if latency is about 200ms.

If the latency is negligible, like <5ms, the downloading speed seems to be normal.

I tried createConnection callback with tls.connect() as well, after setting highWaterMark to 1048576 the speed still didn't seem to recover to normal.

Minimal Reproduction

1. Set up a cloud server VPS and install caddy http2 server on it. For example, the server VPS is located in Los Angeles, United States.
2. Put some download test file on the server VPS.
3. Set up another cloud VPS as the client. For example, the client VPS is located in Singapore.
4. On the client VPS, use curl --http2 to test download speed, which looks normal.
5. Then use something like the following script to test http2 downloading speed in NodeJS, which is very slow.

async function testDownload(VPS_DOMAIN_NAME, TEST_FILENAME) {
    let session = await new Promise((resolve) => {
        http2.connect(`https://${VPS_DOMAIN_NAME}`, (session) => {
            console.log("connected");
            resolve(session);
        });
    });
    let opts = {
        [http2.constants.HTTP2_HEADER_METHOD]: http2.constants.HTTP2_METHOD_GET,
        [http2.constants.HTTP2_HEADER_PATH]: `/${TEST_FILENAME}`,
    }
    let total = 0; startTime = Date.now();
    await new Promise((resolve) => {
        session.request(opts).on('data', (chunk) => {
            total += chunk.byteLength;
            console.log(`${Math.trunc(total / (Date.now() - startTime))} KB/s`);
        }).on('end', () => {
            console.log(`total = ${total}`);
            session.destroy();
            resolve();
        });
    });
}

Output

root@test:~# ping VPS_DOMAIN_NAME
PING VPS_DOMAIN_NAME (VPS_IP) 56(84) bytes of data.
64 bytes from VPS_IP: icmp_seq=1 ttl=54 time=201 ms
root@test:~# curl --http2 https://VPS_DOMAIN/TEST_FILENAME > /dev/null
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  245M  100  245M    0     0  5533k      0  0:00:45  0:00:45 --:--:-- 6470k
root@test:~# node testdownload.js
connected
24 KB/s
47 KB/s
43 KB/s
59 KB/s
73 KB/s
73 KB/s
79 KB/s
92 KB/s
95 KB/s
...
(it climibed up to about 300KB/s and then stayed steady)
...
308 KB/s
308 KB/s
308 KB/s
308 KB/s
308 KB/s
308 KB/s
total = 257062168

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