mirror of https://github.com/electron/electron
255 lines
7.8 KiB
Markdown
255 lines
7.8 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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* `getBlinkMemoryInfo()`
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* `getProcessMemoryInfo()`
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* `getSystemMemoryInfo()`
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* `getSystemVersion()`
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* `getCPUUsage()`
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* `uptime()`
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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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* `contextIsolated`
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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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* `contextId`
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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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## Properties
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### `process.defaultApp` _Readonly_
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A `boolean`. When the app is started by being passed as parameter to the default Electron executable, this
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property is `true` in the main process, otherwise it is `undefined`.
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For example when running the app with `electron .`, it is `true`,
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even if the app is packaged ([`isPackaged`](app.md#appispackaged-readonly)) is `true`.
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This can be useful to determine how many arguments will need to be sliced off from `process.argv`.
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### `process.isMainFrame` _Readonly_
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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` _Readonly_
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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.resourcesPath` _Readonly_
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A `string` representing the path to the resources directory.
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### `process.sandboxed` _Readonly_
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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.contextIsolated` _Readonly_
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A `boolean` that indicates whether the current renderer context has `contextIsolation` enabled.
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It is `undefined` in the main process.
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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` _Readonly_
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A `string` representing the current process's type, can be:
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* `browser` - The main process
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* `renderer` - A renderer process
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* `worker` - In a web worker
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* `utility` - In a node process launched as a service
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### `process.versions.chrome` _Readonly_
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A `string` representing Chrome's version string.
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### `process.versions.electron` _Readonly_
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A `string` representing Electron's version string.
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### `process.windowsStore` _Readonly_
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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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### `process.contextId` _Readonly_
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A `string` (optional) representing a globally unique ID of the current JavaScript context.
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Each frame has its own JavaScript context. When contextIsolation is enabled, the isolated
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world also has a separate JavaScript context.
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This property is only available in the renderer process.
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### `process.parentPort`
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A [`Electron.ParentPort`](parent-port.md) property if this is a [`UtilityProcess`](utility-process.md)
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(or `null` otherwise) allowing communication with the parent process.
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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.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.getBlinkMemoryInfo()`
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Returns `Object`:
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* `allocated` Integer - Size of all allocated objects in Kilobytes.
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* `total` Integer - Total allocated space in Kilobytes.
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Returns an object with Blink memory information.
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It can be useful for debugging rendering / DOM related memory issues.
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Note that all values 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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Example:
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```js
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const version = process.getSystemVersion()
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console.log(version)
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// On macOS -> '10.13.6'
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// On Windows -> '10.0.17763'
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// On Linux -> '4.15.0-45-generic'
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```
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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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