[Bug][Regression]: Running two contexts at same time causes firefox to wait endlessly

[fawazahmed0]

Version

1.50.1

Steps to reproduce

const { firefox } = require('playwright');


let browser

async function begin() {
    while (true) {
        browser = await firefox.launch({ headless: true })
        await Promise.all([run(), run()])
        await browser.close()
    }
}

begin()

async function run() {
    let context = await browser.newContext();
    let page = await context.newPage();
    await page.goto('https://playwright.dev/')
    console.log("completed")
}

Expected behavior

Code should continuously print completed

Actual behavior

Code stops printing completed at some point

Additional context

Running two contexts at same time causes the browser to get stuck for eternity

Note: This is regression, the issue does not happen in 1.49.1

Environment

System:
    OS: Windows 11 10.0.22621
    CPU: (6) x64 AMD FX(tm)-6300 Six-Core Processor
    Memory: 12.64 GB / 23.80 GB
  Binaries:
    Node: 23.6.0 - C:\Program Files\nodejs\node.EXE
    npm: 10.9.2 - C:\Program Files\nodejs\npm.CMD
    bun: 1.1.3 - ~\.bun\bin\bun.EXE
  IDEs:
    VSCode: 1.96.4 - C:\Users\nawaz\AppData\Local\Programs\Microsoft VS Code\bin\code.CMD
  npmPackages:
    @playwright/test: ^1.50.1 => 1.50.1
    playwright: ^1.50.1 => 1.50.1
    playwright-extra: ^4.3.6 => 4.3.6

[dgozman]

I can repro this on Windows, but not on macOS. The second concurrent newPage() hangs, with Browser.newPage call never responding and Browser.attachedToTarget never arriving.