234 lines
7 KiB
Markdown
234 lines
7 KiB
Markdown
# process
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> Extensions to process object.
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Process: [Main](../glossary.md#main-process), [Renderer](../glossary.md#renderer-process)
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Electron's `process` object is extended from the
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[Node.js `process` object](https://nodejs.org/api/process.html).
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It adds the following events, properties, and methods:
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## Sandbox
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In sandboxed renderers the `process` object contains only a subset of the APIs:
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- `crash()`
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- `hang()`
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- `getCreationTime()`
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- `getHeapStatistics()`
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- `getProcessMemoryInfo()`
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- `getSystemMemoryInfo()`
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- `getSystemVersion()`
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- `getCPUUsage()`
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- `getIOCounters()`
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- `argv`
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- `execPath`
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- `env`
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- `pid`
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- `arch`
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- `platform`
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- `sandboxed`
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- `type`
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- `version`
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- `versions`
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- `mas`
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- `windowsStore`
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## Events
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### Event: 'loaded'
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Emitted when Electron has loaded its internal initialization script and is
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beginning to load the web page or the main script.
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It can be used by the preload script to add removed Node global symbols back to
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the global scope when node integration is turned off:
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```javascript
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// preload.js
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const _setImmediate = setImmediate
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const _clearImmediate = clearImmediate
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process.once('loaded', () => {
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global.setImmediate = _setImmediate
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global.clearImmediate = _clearImmediate
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})
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```
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## Properties
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### `process.defaultApp`
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A `Boolean`. When app is started by being passed as parameter to the default app, this
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property is `true` in the main process, otherwise it is `undefined`.
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### `process.isMainFrame`
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A `Boolean`, `true` when the current renderer context is the "main" renderer
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frame. If you want the ID of the current frame you should use `webFrame.routingId`.
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### `process.mas`
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A `Boolean`. For Mac App Store build, this property is `true`, for other builds it is
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`undefined`.
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### `process.noAsar`
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A `Boolean` that controls ASAR support inside your application. Setting this to `true`
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will disable the support for `asar` archives in Node's built-in modules.
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### `process.noDeprecation`
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A `Boolean` that controls whether or not deprecation warnings are printed to `stderr`.
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Setting this to `true` will silence deprecation warnings. This property is used
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instead of the `--no-deprecation` command line flag.
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### `process.enablePromiseAPIs`
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A `Boolean` that controls whether or not deprecation warnings are printed to `stderr` when
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formerly callback-based APIs converted to Promises are invoked using callbacks. Setting this to `true`
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will enable deprecation warnings.
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### `process.resourcesPath`
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A `String` representing the path to the resources directory.
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### `process.sandboxed`
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A `Boolean`. When the renderer process is sandboxed, this property is `true`,
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otherwise it is `undefined`.
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### `process.throwDeprecation`
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A `Boolean` that controls whether or not deprecation warnings will be thrown as
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exceptions. Setting this to `true` will throw errors for deprecations. This
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property is used instead of the `--throw-deprecation` command line flag.
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### `process.traceDeprecation`
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A `Boolean` that controls whether or not deprecations printed to `stderr` include
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their stack trace. Setting this to `true` will print stack traces for deprecations.
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This property is instead of the `--trace-deprecation` command line flag.
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### `process.traceProcessWarnings`
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A `Boolean` that controls whether or not process warnings printed to `stderr` include
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their stack trace. Setting this to `true` will print stack traces for process warnings
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(including deprecations). This property is instead of the `--trace-warnings` command
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line flag.
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### `process.type`
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A `String` representing the current process's type, can be `"browser"` (i.e. main process), `"renderer"`, or `"worker"` (i.e. web worker).
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### `process.versions.chrome`
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A `String` representing Chrome's version string.
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### `process.versions.electron`
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A `String` representing Electron's version string.
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### `process.windowsStore`
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A `Boolean`. If the app is running as a Windows Store app (appx), this property is `true`,
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for otherwise it is `undefined`.
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## Methods
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The `process` object has the following methods:
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### `process.crash()`
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Causes the main thread of the current process crash.
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### `process.getCreationTime()`
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Returns `Number | null` - The number of milliseconds since epoch, or `null` if the information is unavailable
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Indicates the creation time of the application.
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The time is represented as number of milliseconds since epoch. It returns null if it is unable to get the process creation time.
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### `process.getCPUUsage()`
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Returns [`CPUUsage`](structures/cpu-usage.md)
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### `process.getIOCounters()` _Windows_ _Linux_
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Returns [`IOCounters`](structures/io-counters.md)
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### `process.getHeapStatistics()`
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Returns `Object`:
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* `totalHeapSize` Integer
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* `totalHeapSizeExecutable` Integer
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* `totalPhysicalSize` Integer
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* `totalAvailableSize` Integer
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* `usedHeapSize` Integer
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* `heapSizeLimit` Integer
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* `mallocedMemory` Integer
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* `peakMallocedMemory` Integer
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* `doesZapGarbage` Boolean
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Returns an object with V8 heap statistics. Note that all statistics are reported in Kilobytes.
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### `process.getProcessMemoryInfo()`
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Returns `Promise<ProcessMemoryInfo>` - Resolves with a [ProcessMemoryInfo](structures/process-memory-info.md)
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Returns an object giving memory usage statistics about the current process. Note
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that all statistics are reported in Kilobytes.
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This api should be called after app ready.
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Chromium does not provide `residentSet` value for macOS. This is because macOS
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performs in-memory compression of pages that haven't been recently used. As a
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result the resident set size value is not what one would expect. `private` memory
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is more representative of the actual pre-compression memory usage of the process
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on macOS.
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### `process.getSystemMemoryInfo()`
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Returns `Object`:
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* `total` Integer - The total amount of physical memory in Kilobytes available to the
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system.
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* `free` Integer - The total amount of memory not being used by applications or disk
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cache.
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* `swapTotal` Integer _Windows_ _Linux_ - The total amount of swap memory in Kilobytes available to the
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system.
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* `swapFree` Integer _Windows_ _Linux_ - The free amount of swap memory in Kilobytes available to the
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system.
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Returns an object giving memory usage statistics about the entire system. Note
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that all statistics are reported in Kilobytes.
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### `process.getSystemVersion()`
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Returns `String` - The version of the host operating system.
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Examples:
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| Platform | Version |
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| macOS | `10.13.6` |
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| Windows | `10.0.17763` |
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| Linux | `4.15.0-45-generic` |
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**Note:** It returns the actual operating system version instead of kernel version on macOS unlike `os.release()`.
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### `process.takeHeapSnapshot(filePath)`
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* `filePath` String - Path to the output file.
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Returns `Boolean` - Indicates whether the snapshot has been created successfully.
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Takes a V8 heap snapshot and saves it to `filePath`.
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### `process.hang()`
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Causes the main thread of the current process hang.
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### `process.setFdLimit(maxDescriptors)` _macOS_ _Linux_
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* `maxDescriptors` Integer
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Sets the file descriptor soft limit to `maxDescriptors` or the OS hard
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limit, whichever is lower for the current process.
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