Closing a BrowserWindow with set affinity and electron.remote usage from a preload script will freeze similar BrowserWindows.

[markleutloff]

• Electron Version: >= 6.0.0-beta.13, 6.0.0, 6.0.1, 6.0.2, 7.0.0-beta.1, 7.0.0-beta.2
• Operating System (Platform and Version): Windows 10
• Last known working Electron version: 5.0.9, <= 6.0.0-beta.12

Expected Behavior
Closing the BrowserWindow should not freeze other BrowserWindows.

Actual behavior
Similar BrowserWindows will freeze.

To Reproduce
Create a two BrowserWindows with identical webPreferences set to:
preload: some preload script
affinity: some affinity

index.js:

const {app, BrowserWindow} = require('electron')

function createWindow () {
    const browserWindow = new BrowserWindow({
        width: 800,
        height: 600,
        webPreferences: {
            preload: "PATH_TO_PRELOAD.js",
            affinity: "Test"
        }
    })

    browserWindow.loadFile('index.html')
}

app.on('ready', () => {
    createWindow();
    createWindow();
})

app.on('window-all-closed', function () {
    app.quit()
})

preload.js:

// Thats all what is needed to make it break
const { remote } = require("electron");

Additional Information
Just by using electron.remote this issue occours. To test the freeze effect, just try to select some text in the remaining window.

[MarshallOfSound]

This is why the affinity API is flagged as experimental, what you are seeing here is a deadlock between two renderers with synchronous IPC.

The end game is for affinity to be removed along with all of our other patches to the Chromium process model to avoid scenarios like this. See #18397