2017-03-15 10:34:21 +00:00
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# Multithreading
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With [Web Workers][web-workers], it is possible to run JavaScript in OS-level
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threads.
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## Multi-threaded Node.js
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In Electron, it is supported to use Node.js integration in Web Workers. To do
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so the `nodeIntegrationInWorker` option should be set to `true` in
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`webPreferences`.
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```javascript
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let win = new BrowserWindow({
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webPreferences: {
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nodeIntegrationInWorker: true
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}
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})
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```
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The `nodeIntegrationInWorker` can be used independent of `nodeIntegration`, but
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`sandbox` must not be set to `true`.
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## Available APIs
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All built-in modules of Node.js are supported in Web Workers, and `asar`
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archives can still be read with Node.js APIs. However non of Electron's built-in
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modules can be used in multi-threaded environment.
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## Native Node.js modules
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Any native Node.js module can be loaded directly in Web Workers, but it is
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strongly recommended not to do so. Most existing native modules have been
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2017-03-15 11:07:28 +00:00
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written assuming single-thread environment, using them in Web Workers will
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2017-03-15 10:34:21 +00:00
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lead to crashes and memory corruptions.
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Even when using a thread-safe native Node.js module, it should be noticed that
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the `process.dlopen` function is not thread safe, so loading a native module
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in Web Workers is not thread safe.
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The only way to load a native module safely for now, is to make sure the app
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loads no native modules after the Web Workers get started.
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```javascript
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process.dlopen = () => {
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throw new Error('Load native module is not safe')
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}
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new Worker('script.js')
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```
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[web-workers]: https://developer.mozilla.org/en/docs/Web/API/Web_Workers_API/Using_web_workers
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