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doc: add subprocess.ref() and subprocess.unref()

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PR-URL: https://github.com/nodejs/node/pull/22220
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Bryan English <bryan@bryanenglish.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
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Thomas Hunter II 2018-08-09 14:46:07 -07:00 committed by Vse Mozhet Byt
parent dcfd323c6b
commit 7b1f3a4133
1 changed files with 50 additions and 5 deletions
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doc/api/child_process.md
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@ -536,11 +536,12 @@ process will be made the leader of a new process group and session. Note that
child processes may continue running after the parent exits regardless of
whether they are detached or not. See setsid(2) for more information.
By default, the parent will wait for the detached child to exit. To prevent
the parent from waiting for a given `subprocess`, use the `subprocess.unref()`
method. Doing so will cause the parent's event loop to not include the child in
its reference count, allowing the parent to exit independently of the child,
unless there is an established IPC channel between the child and parent.
By default, the parent will wait for the detached child to exit. To prevent the
parent from waiting for a given `subprocess` to exit, use the
`subprocess.unref()` method. Doing so will cause the parent's event loop to not
include the child in its reference count, allowing the parent to exit
independently of the child, unless there is an established IPC channel between
the child and the parent.
When using the `detached` option to start a long-running process, the process
will not stay running in the background after the parent exits unless it is
@ -1094,6 +1095,27 @@ console.log(`Spawned child pid: ${grep.pid}`);
grep.stdin.end();
```
### subprocess.ref()
<!-- YAML
added: v0.7.10
-->
Calling `subprocess.ref()` after making a call to `subprocess.unref()` will
restore the removed reference count for the child process, forcing the parent
to wait for the child to exit before exiting itself.
```js
const { spawn } = require('child_process');
const subprocess = spawn(process.argv[0], ['child_program.js'], {
detached: true,
stdio: 'ignore'
});
subprocess.unref();
subprocess.ref();
```
### subprocess.send(message[, sendHandle[, options]][, callback])
<!-- YAML
added: v0.5.9
@ -1362,6 +1384,29 @@ then this will be `null`.
`subprocess.stdout` is an alias for `subprocess.stdio[1]`. Both properties will
refer to the same value.
### subprocess.unref()
<!-- YAML
added: v0.7.10
-->
By default, the parent will wait for the detached child to exit. To prevent the
parent from waiting for a given `subprocess` to exit, use the
`subprocess.unref()` method. Doing so will cause the parent's event loop to not
include the child in its reference count, allowing the parent to exit
independently of the child, unless there is an established IPC channel between
the child and the parent.
```js
const { spawn } = require('child_process');
const subprocess = spawn(process.argv[0], ['child_program.js'], {
detached: true,
stdio: 'ignore'
});
subprocess.unref();
```
## `maxBuffer` and Unicode
The `maxBuffer` option specifies the largest number of bytes allowed on `stdout`