[Bug]: node:events:496; Error: write EPIPE

[bourbonut]

Version

1.41.1

Steps to reproduce

Environment

• Python Version: 3.9.18
• Playwright Browser : Chromium

Python Dependencies

• Quart Version : 0.19.4
• Hypercorn Version : 0.16.0

Code

import signal
import logging
import asyncio
from quart import Quart
from playwright.async_api import async_playwright
from hypercorn.asyncio import serve
from hypercorn import Config

# logging.disable(logging.CRITICAL)

app = Quart(__name__)

@app.route("/")
async def index():
    return "<hml>Hello world</html>"

shutdown_event = asyncio.Event()

async def test(loop):
    print("Test")
    async with async_playwright() as p:
        print("Start")
        browser = await p.chromium.launch()
        context = await browser.new_context(device_scale_factor=1)
        page = await context.new_page()
        print("Page created")
        await page.goto("http://localhost:5000")
        print("Goto page")
        await page.screenshot(path="hello.png", type='png')
    print("Finished")
    shutdown_event.set()


config = Config()
config.bind = ["localhost:5000"]

def save():
    loop = asyncio.get_event_loop()
    loop.create_task(test(loop))
    loop.run_until_complete(
        serve(app, config, shutdown_trigger=shutdown_event.wait)
    )
    print("End")

save()
save()

Expected behavior

If I don't duplicate the task, I don't have any error:

import signal
import logging
import asyncio
from quart import Quart
from playwright.async_api import async_playwright
from hypercorn.asyncio import serve
from hypercorn import Config

# logging.disable(logging.CRITICAL)

def make_message(message):
    app = Quart(__name__)

    @app.route("/")
    async def index():
        return f"<hml>{message}</html>"

    shutdown_event = asyncio.Event()

    async def test(loop):
        print("Test")
        async with async_playwright() as p:
            print("Start")
            browser = await p.chromium.launch()
            context = await browser.new_context(device_scale_factor=1)
            page = await context.new_page()
            print("Page created")
            await page.goto("http://localhost:5000")
            print("Goto page")
            await page.screenshot(path="hello.png", type='png')
        print("Finished")
        shutdown_event.set()


    config = Config()
    config.bind = ["localhost:5000"]

    def save():
        loop = asyncio.get_event_loop()
        loop.create_task(test(loop))
        loop.run_until_complete(
            serve(app, config, shutdown_trigger=shutdown_event.wait)
        )
        print("End")

    return save

make_message("Hello world")()
make_message("Me again")() # No error

Actual behavior

I got this error :

Test
[2024-02-04 22:05:29 +0100] [36736] [INFO] Running on http://127.0.0.1:5000 (CTRL + C to quit)
Start
Page created
Goto page
Finished
End
Test
[2024-02-04 22:05:29 +0100] [36736] [INFO] Running on http://127.0.0.1:5000 (CTRL + C to quit)
End
node:events:496
      throw er; // Unhandled 'error' event
      ^

Error: write EPIPE
    at afterWriteDispatched (node:internal/stream_base_commons:160:15)
    at writeGeneric (node:internal/stream_base_commons:151:3)
    at Socket._writeGeneric (node:net:952:11)
    at Socket._write (node:net:964:8)
    at writeOrBuffer (node:internal/streams/writable:564:12)
    at _write (node:internal/streams/writable:493:10)
    at Writable.write (node:internal/streams/writable:502:10)
    at PipeTransport.send (/home/nut/github/detroit/.venv/lib/python3.9/site-packages/playwright/driver/package/lib/protocol/transport.js:51:21)
    at dispatcherConnection.onmessage (/home/nut/github/detroit/.venv/lib/python3.9/site-packages/playwright/driver/package/lib/cli/driver.js:53:57)
    at DispatcherConnection._sendMessageToClient (/home/nut/github/detroit/.venv/lib/python3.9/site-packages/playwright/driver/package/lib/server/dispatchers/dispatcher.js:216:10)
Emitted 'error' event on Socket instance at:
    at emitErrorNT (node:internal/streams/destroy:169:8)
    at emitErrorCloseNT (node:internal/streams/destroy:128:3)
    at process.processTicksAndRejections (node:internal/process/task_queues:82:21) {
  errno: -32,
  code: 'EPIPE',
  syscall: 'write'
}

Node.js v20.11.0

Additional context

No response

Environment

System:
    OS: Linux 5.15 Ubuntu 20.04.6 LTS (Focal Fossa)
    CPU: (8) x64 Intel(R) Core(TM) i7-9700F CPU @ 3.00GHz
    Memory: 6.21 GB / 15.52 GB
    Container: Yes
  Binaries:
    Node: 14.21.3 - /usr/bin/node
    Yarn: 1.22.19 - /usr/bin/yarn
    npm: 6.14.18 - /usr/bin/npm
  Languages:
    Bash: 5.0.17 - /usr/bin/bash

[mxschmitt]

The issue in your code is that you forget to call shutdown_event.clear() before printing the "End". This means that in the second iteration, it would immediately return in loop.run_until_complete( and no graceful cleanup / teardown can happen.

Modifying save() to:

def save():
    loop = asyncio.get_event_loop()
    loop.create_task(test(loop))
    loop.run_until_complete(
        serve(app, config, shutdown_trigger=shutdown_event.wait)
    )
    shutdown_event.clear()
    print("End")

makes it work 10/10 times.

[bourbonut]

It works ! Thank you for your help 💯