Cluster | Node.js v20.1.0 Documentation - Kiến Thức Cho Người lao Động Việt Nam

Source Code: lib/cluster.js

Clusters of Node.js processes can be used to run multiple instances of Node.js
that can distribute workloads among their application threads. When process
isolation is not needed, use the worker_threads module instead, which
allows running multiple application threads within a single Node.js instance.

The cluster module allows easy creation of child processes that all share
server ports.

import
 cluster from
 'node:cluster';
import
 http from
 'node:http';
import
 { availableParallelism } from
 'node:os';
import
 process from
 'node:process';

const
 numCPUs = availableParallelism();

if
 (cluster.isPrimary) {
  console
.log
(`Primary 
${process.pid} is running`);

   
  for
 (let
 i = 0; i < numCPUs; i++) {
    cluster.fork();
  }

  cluster.on
('exit'
, (
worker, code, signal) => {
    console
.log
(`worker 
${worker.process.pid} died`);
  });
} else {
   
   
  http.createServer
((
req, res) => {
    res.writeHead
(200);
    res.end
('hello world\n');
  }).listen
(8000);

  console
.log
(`Worker 
${process.pid} started`);
}const
 cluster = require
('node:cluster');
const
 http = require
('node:http');
const
 numCPUs = require
('node:os'
).availableParallelism();
const
 process = require
('node:process');

if
 (cluster.isPrimary) {
  console
.log
(`Primary 
${process.pid} is running`);

   
  for
 (let
 i = 0; i < numCPUs; i++) {
    cluster.fork();
  }

  cluster.on
('exit'
, (
worker, code, signal) => {
    console
.log
(`worker 
${worker.process.pid} died`);
  });
} else {
   
   
  http.createServer
((
req, res) => {
    res.writeHead
(200);
    res.end
('hello world\n');
  }).listen
(8000);

  console
.log
(`Worker 
${process.pid} started`);
}

Running Node.js will now share port 8000 between the workers:

$ 
node server.js
Primary 3596 is running
Worker 4324 started
Worker 4520 started
Worker 6056 started
Worker 5644 started

On Windows, it is not yet possible to set up a named pipe server in a worker.

How it works#

The worker processes are spawned using the child_process.fork() method,
so that they can communicate with the parent via IPC and pass server
handles back and forth.

The cluster module supports two methods of distributing incoming
connections.

The first one (and the default one on all platforms except Windows)
is the round-robin approach, where the primary process listens on a
port, accepts new connections and distributes them across the workers
in a round-robin fashion, with some built-in smarts to avoid
overloading a worker process.

The second approach is where the primary process creates the listen
socket and sends it to interested workers. The workers then accept
incoming connections directly.

The second approach should, in theory, give the best performance.
In practice however, distribution tends to be very unbalanced due
to operating system scheduler vagaries. Loads have been observed
where over 70% of all connections ended up in just two processes,
out of a total of eight.

Because server.listen() hands off most of the work to the primary
process, there are three cases where the behavior between a normal
Node.js process and a cluster worker differs:

server.listen({fd: 7}) Because the message is passed to the primary,
file descriptor 7 in the parent will be listened on, and the
handle passed to the worker, rather than listening to the worker’s
idea of what the number 7 file descriptor references.
server.listen(handle) Listening on handles explicitly will cause
the worker to use the supplied handle, rather than talk to the primary
process.
server.listen(0) Normally, this will cause servers to listen on a
random port. However, in a cluster, each worker will receive the
same “random” port each time they do listen(0). In essence, the
port is random the first time, but predictable thereafter. To listen
on a unique port, generate a port number based on the cluster worker ID.

Node.js does not provide routing logic. It is therefore important to design an
application such that it does not rely too heavily on in-memory data objects for
things like sessions and login.

Because workers are all separate processes, they can be killed or
re-spawned depending on a program’s needs, without affecting other
workers. As long as there are some workers still alive, the server will
continue to accept connections. If no workers are alive, existing connections
will be dropped and new connections will be refused. Node.js does not
automatically manage the number of workers, however. It is the application’s
responsibility to manage the worker pool based on its own needs.

Although a primary use case for the node:cluster module is networking, it can
also be used for other use cases requiring worker processes.

Class: `Worker`#

Added in: v0.7.0

Extends: <EventEmitter>

A Worker object contains all public information and method about a worker.
In the primary it can be obtained using cluster.workers. In a worker
it can be obtained using cluster.worker.

Event: `'disconnect'`#

Added in: v0.7.7

Similar to the cluster.on('disconnect') event, but specific to this worker.

cluster.fork
().on
('disconnect'
, () => {
   
});

Event: `'error'`#

Added in: v0.7.3

This event is the same as the one provided by child_process.fork().

Within a worker, process.on('error') may also be used.

Event: `'exit'`#

Added in: v0.11.2

code <number> The exit code, if it exited normally.
signal <string> The name of the signal (e.g. 'SIGHUP') that caused
the process to be killed.

Similar to the cluster.on('exit') event, but specific to this worker.

import
 cluster from
 'node:cluster';

if
 (cluster.isPrimary) {
  const
 worker = cluster.fork();
  worker.on
('exit'
, (
code, signal) => {
    if (signal) {
      console
.log
(`worker was killed by signal: 
${signal}`);
    } else
 if
 (code !== 0) {
      console
.log
(`worker exited with error code: 
${code}`);
    } else {
      console
.log
('worker success!');
    }
  });
}const
 cluster = require
('node:cluster');

if
 (cluster.isPrimary) {
  const
 worker = cluster.fork();
  worker.on
('exit'
, (
code, signal) => {
    if (signal) {
      console
.log
(`worker was killed by signal: 
${signal}`);
    } else
 if
 (code !== 0) {
      console
.log
(`worker exited with error code: 
${code}`);
    } else {
      console
.log
('worker success!');
    }
  });
}

Event: `'listening'`#

Added in: v0.7.0

address <Object>

Similar to the cluster.on('listening') event, but specific to this worker.

cluster.fork
().on
('listening'
, (
address) => {
   
});cluster.fork
().on
('listening'
, (
address) => {
   
});

It is not emitted in the worker.

Event: `'message'`#

Added in: v0.7.0

message <Object>
handle <undefined> | <Object>

Similar to the 'message' event of cluster, but specific to this worker.

Within a worker, process.on('message') may also be used.

See process event: 'message'.

Here is an example using the message system. It keeps a count in the primary
process of the number of HTTP requests received by the workers:

import
 cluster from
 'node:cluster';
import
 http from
 'node:http';
import
 { availableParallelism } from
 'node:os';
import
 process from
 'node:process';

if
 (cluster.isPrimary) {

   
  let
 numReqs = 0;
  setInterval
(() => {
    console
.log
(`numReqs = 
${numReqs}`);
  }, 1000);

   
  function
 messageHandler
(msg) {
    if
 (msg.cmd
 && msg.cmd
 === 'notifyRequest') {
      numReqs += 1;
    }
  }

   
  const
 numCPUs = availableParallelism();
  for
 (let
 i = 0; i < numCPUs; i++) {
    cluster.fork();
  }

  for
 (const
 id in
 cluster.workers) {
    cluster.workers
[id].on
('message', messageHandler);
  }

} else {

   
  http.Server
((
req, res) => {
    res.writeHead
(200);
    res.end
('hello world\n');

     
    process.send
({ cmd
: 'notifyRequest' });
  }).listen
(8000);
}const
 cluster = require
('node:cluster');
const
 http = require
('node:http');
const
 process = require
('node:process');

if
 (cluster.isPrimary) {

   
  let
 numReqs = 0;
  setInterval
(() => {
    console
.log
(`numReqs = 
${numReqs}`);
  }, 1000);

   
  function
 messageHandler
(msg) {
    if
 (msg.cmd
 && msg.cmd
 === 'notifyRequest') {
      numReqs += 1;
    }
  }

   
  const
 numCPUs = require
('node:os'
).availableParallelism();
  for
 (let
 i = 0; i < numCPUs; i++) {
    cluster.fork();
  }

  for
 (const
 id in
 cluster.workers) {
    cluster.workers
[id].on
('message', messageHandler);
  }

} else {

   
  http.Server
((
req, res) => {
    res.writeHead
(200);
    res.end
('hello world\n');

     
    process.send
({ cmd
: 'notifyRequest' });
  }).listen
(8000);
}

Event: `'online'`#

Added in: v0.7.0

Similar to the cluster.on('online') event, but specific to this worker.

cluster.fork
().on
('online'
, () => {
   
});

It is not emitted in the worker.

`worker.disconnect()`#

History

VersionChanges
v7.3.0

This method now returns a reference to worker.

v0.7.7

Added in: v0.7.7

Returns: <cluster.Worker> A reference to worker.

In a worker, this function will close all servers, wait for the 'close' event
on those servers, and then disconnect the IPC channel.

In the primary, an internal message is sent to the worker causing it to call
.disconnect() on itself.

Causes .exitedAfterDisconnect to be set.

After a server is closed, it will no longer accept new connections,
but connections may be accepted by any other listening worker. Existing
connections will be allowed to close as usual. When no more connections exist,
see server.close(), the IPC channel to the worker will close allowing it
to die gracefully.

The above applies only to server connections, client connections are not
automatically closed by workers, and disconnect does not wait for them to close
before exiting.

In a worker, process.disconnect exists, but it is not this function;
it is disconnect().

Because long living server connections may block workers from disconnecting, it
may be useful to send a message, so application specific actions may be taken to
close them. It also may be useful to implement a timeout, killing a worker if
the 'disconnect' event has not been emitted after some time.

if
 (cluster.isPrimary) {
  const
 worker = cluster.fork();
  let timeout;

  worker.on
('listening'
, (
address) => {
    worker.send
('shutdown');
    worker.disconnect();
    timeout = setTimeout
(() => {
      worker.kill();
    }, 2000);
  });

  worker.on
('disconnect'
, () => {
    clearTimeout(timeout);
  });

} else
 if
 (cluster.isWorker) {
  const
 net = require
('node:net');
  const
 server = net.createServer
((
socket) => {
     
  });

  server.listen
(8000);

  process.on
('message'
, (
msg) => {
    if
 (msg === 'shutdown') {
       
    }
  });
}

`worker.exitedAfterDisconnect`#

Added in: v6.0.0

<boolean>

This property is true if the worker exited due to .disconnect().
If the worker exited any other way, it is false. If the
worker has not exited, it is undefined.

The boolean worker.exitedAfterDisconnect allows distinguishing between
voluntary and accidental exit, the primary may choose not to respawn a worker
based on this value.

cluster.on
('exit'
, (
worker, code, signal) => {
  if
 (worker.exitedAfterDisconnect
 === true) {
    console
.log
('Oh, it was just voluntary – no need to worry');
  }
});

 
worker.kill
();

`worker.id`#

Added in: v0.8.0

<integer>

Each new worker is given its own unique id, this id is stored in the
id.

While a worker is alive, this is the key that indexes it in
cluster.workers.

`worker.isConnected()`#

Added in: v0.11.14

This function returns true if the worker is connected to its primary via its
IPC channel, false otherwise. A worker is connected to its primary after it
has been created. It is disconnected after the 'disconnect' event is emitted.

`worker.isDead()`#

Added in: v0.11.14

This function returns true if the worker’s process has terminated (either
because of exiting or being signaled). Otherwise, it returns false.

import
 cluster from
 'node:cluster';
import
 http from
 'node:http';
import
 { availableParallelism } from
 'node:os';
import
 process from
 'node:process';

const
 numCPUs = availableParallelism();

if
 (cluster.isPrimary) {
  console
.log
(`Primary 
${process.pid} is running`);

   
  for
 (let
 i = 0; i < numCPUs; i++) {
    cluster.fork();
  }

  cluster.on
('fork'
, (
worker) => {
    console
.log
('worker is dead:'
, worker.isDead());
  });

  cluster.on
('exit'
, (
worker, code, signal) => {
    console
.log
('worker is dead:'
, worker.isDead());
  });
} else {
   
  http.createServer
((
req, res) => {
    res.writeHead
(200);
    res.end
(`Current process\n 
${process.pid}`);
    process.kill
(process.pid);
  }).listen
(8000);
}const
 cluster = require
('node:cluster');
const
 http = require
('node:http');
const
 numCPUs = require
('node:os'
).availableParallelism();
const
 process = require
('node:process');

if
 (cluster.isPrimary) {
  console
.log
(`Primary 
${process.pid} is running`);

   
  for
 (let
 i = 0; i < numCPUs; i++) {
    cluster.fork();
  }

  cluster.on
('fork'
, (
worker) => {
    console
.log
('worker is dead:'
, worker.isDead());
  });

  cluster.on
('exit'
, (
worker, code, signal) => {
    console
.log
('worker is dead:'
, worker.isDead());
  });
} else {
   
  http.createServer
((
req, res) => {
    res.writeHead
(200);
    res.end
(`Current process\n 
${process.pid}`);
    process.kill
(process.pid);
  }).listen
(8000);
}

`worker.kill([signal])`#

Added in: v0.9.12

signal <string> Name of the kill signal to send to the worker
process. Default: 'SIGTERM'

This function will kill the worker. In the primary worker, it does this by
disconnecting the worker.process, and once disconnected, killing with
signal. In the worker, it does it by killing the process with signal.

The kill() function kills the worker process without waiting for a graceful
disconnect, it has the same behavior as worker.process.kill().

This method is aliased as worker.destroy() for backwards compatibility.

In a worker, process.kill() exists, but it is not this function;
it is kill().

`worker.process`#

Added in: v0.7.0

<ChildProcess>

All workers are created using child_process.fork(), the returned object
from this function is stored as .process. In a worker, the global process
is stored.

See: Child Process module.

Workers will call process.exit(0) if the 'disconnect' event occurs
on process and .exitedAfterDisconnect is not true. This protects against
accidental disconnection.

`worker.send(message[, sendHandle[, options]][, callback])`#

History

VersionChanges
v4.0.0

The callback parameter is supported now.

v0.7.0

Added in: v0.7.0

message <Object>
sendHandle <Handle>
options <Object> The options argument, if present, is an object used to
parameterize the sending of certain types of handles. options supports
the following properties:
- keepOpen <boolean> A value that can be used when passing instances of
  net.Socket. When true, the socket is kept open in the sending process.
  Default: false.
callback <Function>
Returns: <boolean>

Send a message to a worker or primary, optionally with a handle.

In the primary, this sends a message to a specific worker. It is identical to
ChildProcess.send().

In a worker, this sends a message to the primary. It is identical to
process.send().

This example will echo back all messages from the primary:

if
 (cluster.isPrimary) {
  const
 worker = cluster.fork();
  worker.send
('hi there');

} else
 if
 (cluster.isWorker) {
  process.on
('message'
, (
msg) => {
    process.send(msg);
  });
}

Event: `'disconnect'`#

Added in: v0.7.9

worker <cluster.Worker>

Emitted after the worker IPC channel has disconnected. This can occur when a
worker exits gracefully, is killed, or is disconnected manually (such as with
worker.disconnect()).

There may be a delay between the 'disconnect' and 'exit' events. These
events can be used to detect if the process is stuck in a cleanup or if there
are long-living connections.

cluster.on
('disconnect'
, (
worker) => {
  console
.log
(`The worker #
${worker.id} has disconnected`);
});

Event: `'exit'`#

Added in: v0.7.9

worker <cluster.Worker>
code <number> The exit code, if it exited normally.
signal <string> The name of the signal (e.g. 'SIGHUP') that caused
the process to be killed.

When any of the workers die the cluster module will emit the 'exit' event.

This can be used to restart the worker by calling .fork() again.

cluster.on
('exit'
, (
worker, code, signal) => {
  console
.log
('worker %d died (%s). restarting...',
              worker.process
.pid, signal || code);
  cluster.fork();
});

See child_process event: 'exit'.

Event: `'fork'`#

Added in: v0.7.0

worker <cluster.Worker>

When a new worker is forked the cluster module will emit a 'fork' event.
This can be used to log worker activity, and create a custom timeout.

const timeouts = [];
function
 errorMsg
() {
  console
.error
('Something must be wrong with the connection ...');
}

cluster.on
('fork'
, (
worker) => {
  timeouts[worker.id
] = setTimeout
(errorMsg, 2000);
});
cluster.on
('listening'
, (
worker, address) => {
  clearTimeout
(timeouts[worker.id]);
});
cluster.on
('exit'
, (
worker, code, signal) => {
  clearTimeout
(timeouts[worker.id]);
  errorMsg();
});

Event: `'listening'`#

Added in: v0.7.0

worker <cluster.Worker>
address <Object>

After calling listen() from a worker, when the 'listening' event is emitted
on the server, a 'listening' event will also be emitted on cluster in the
primary.

The event handler is executed with two arguments, the worker contains the
worker object and the address object contains the following connection
properties: address, port, and addressType. This is very useful if the
worker is listening on more than one address.

cluster.on
('listening'
, (
worker, address) => {
  console
.log(
    `A worker is now connected to 
${address.address}
:${address.port}`);
});

The addressType is one of:

4 (TCPv4)
6 (TCPv6)
-1 (Unix domain socket)
'udp4' or 'udp6' (UDPv4 or UDPv6)

Event: `'message'`#

History

VersionChanges
v6.0.0

The worker parameter is passed now; see below for details.

v2.5.0

Added in: v2.5.0

worker <cluster.Worker>
message <Object>
handle <undefined> | <Object>

Emitted when the cluster primary receives a message from any worker.

See child_process event: 'message'.

Event: `'online'`#

Added in: v0.7.0

worker <cluster.Worker>

After forking a new worker, the worker should respond with an online message.
When the primary receives an online message it will emit this event.
The difference between 'fork' and 'online' is that fork is emitted when the
primary forks a worker, and 'online' is emitted when the worker is running.

cluster.on
('online'
, (
worker) => {
  console
.log
('Yay, the worker responded after it was forked');
});

Event: `'setup'`#

Added in: v0.7.1

settings <Object>

Emitted every time .setupPrimary() is called.

The settings object is the cluster.settings object at the time
.setupPrimary() was called and is advisory only, since multiple calls to
.setupPrimary() can be made in a single tick.

If accuracy is important, use cluster.settings.

`cluster.disconnect([callback])`#

Added in: v0.7.7

callback <Function> Called when all workers are disconnected and handles are
closed.

Calls .disconnect() on each worker in cluster.workers.

When they are disconnected all internal handles will be closed, allowing the
primary process to die gracefully if no other event is waiting.

The method takes an optional callback argument which will be called when
finished.

This can only be called from the primary process.

`cluster.fork([env])`#

Added in: v0.6.0

env <Object> Key/value pairs to add to worker process environment.
Returns: <cluster.Worker>

Spawn a new worker process.

This can only be called from the primary process.

`cluster.isMaster`#

Added in: v0.8.1

Deprecated since: v16.0.0

Deprecated alias for cluster.isPrimary.

`cluster.isPrimary`#

Added in: v16.0.0

<boolean>

True if the process is a primary. This is determined
by the process.env.NODE_UNIQUE_ID. If process.env.NODE_UNIQUE_ID is
undefined, then isPrimary is true.

`cluster.isWorker`#

Added in: v0.6.0

<boolean>

True if the process is not a primary (it is the negation of cluster.isPrimary).

`cluster.schedulingPolicy`#

Added in: v0.11.2

The scheduling policy, either cluster.SCHED_RR for round-robin or
cluster.SCHED_NONE to leave it to the operating system. This is a
global setting and effectively frozen once either the first worker is spawned,
or .setupPrimary() is called, whichever comes first.

SCHED_RR is the default on all operating systems except Windows.
Windows will change to SCHED_RR once libuv is able to effectively
distribute IOCP handles without incurring a large performance hit.

cluster.schedulingPolicy can also be set through the
NODE_CLUSTER_SCHED_POLICY environment variable. Valid
values are 'rr' and 'none'.

`cluster.settings`#

History

VersionChanges
v13.2.0, v12.16.0

The serialization option is supported now.

v9.5.0

The cwd option is supported now.

v9.4.0

The windowsHide option is supported now.

v8.2.0

The inspectPort option is supported now.

v6.4.0

The stdio option is supported now.

v0.7.1

Added in: v0.7.1

<Object>
- execArgv <string[]> List of string arguments passed to the Node.js
  executable. Default: process.execArgv.
- exec <string> File path to worker file. Default: process.argv[1].
- args <string[]> String arguments passed to worker.
  Default: process.argv.slice(2).
- cwd <string> Current working directory of the worker process. Default:
  undefined (inherits from parent process).
- serialization <string> Specify the kind of serialization used for sending
  messages between processes. Possible values are 'json' and 'advanced'.
  See Advanced serialization for child_process for more details.
  Default: false.
- silent <boolean> Whether or not to send output to parent’s stdio.
  Default: false.
- stdio <Array> Configures the stdio of forked processes. Because the
  cluster module relies on IPC to function, this configuration must contain an
  'ipc' entry. When this option is provided, it overrides silent.
- uid <number> Sets the user identity of the process. (See setuid(2).)
- gid <number> Sets the group identity of the process. (See setgid(2).)
- inspectPort <number> | <Function> Sets inspector port of worker.
  This can be a number, or a function that takes no arguments and returns a
  number. By default each worker gets its own port, incremented from the
  primary’s process.debugPort.
- windowsHide <boolean> Hide the forked processes console window that would
  normally be created on Windows systems. Default: false.

After calling .setupPrimary() (or .fork()) this settings object will
contain the settings, including the default values.

This object is not intended to be changed or set manually.

`cluster.setupMaster([settings])`#

History

VersionChanges
v16.0.0

Deprecated since: v16.0.0

v6.4.0

The stdio option is supported now.

v0.7.1

Added in: v0.7.1

Deprecated alias for .setupPrimary().

`cluster.setupPrimary([settings])`#

Added in: v16.0.0

settings <Object> See cluster.settings.

setupPrimary is used to change the default ‘fork’ behavior. Once called,
the settings will be present in cluster.settings.

Any settings changes only affect future calls to .fork() and have no
effect on workers that are already running.

The only attribute of a worker that cannot be set via .setupPrimary() is
the env passed to .fork().

The defaults above apply to the first call only; the defaults for later
calls are the current values at the time of cluster.setupPrimary() is called.

import
 cluster from
 'node:cluster';

cluster.setupPrimary({
  exec
: 'worker.js',
  args
: ['--use'
, 'https'],
  silent
: true,
});
cluster.fork();  
cluster.setupPrimary({
  exec
: 'worker.js',
  args
: ['--use'
, 'http'],
});
cluster.fork
(); const
 cluster = require
('node:cluster');

cluster.setupPrimary({
  exec
: 'worker.js',
  args
: ['--use'
, 'https'],
  silent
: true,
});
cluster.fork();  
cluster.setupPrimary({
  exec
: 'worker.js',
  args
: ['--use'
, 'http'],
});
cluster.fork
();

This can only be called from the primary process.

`cluster.worker`#

Added in: v0.7.0

<Object>

A reference to the current worker object. Not available in the primary process.

import
 cluster from
 'node:cluster';

if
 (cluster.isPrimary) {
  console
.log
('I am primary');
  cluster.fork();
  cluster.fork();
} else
 if
 (cluster.isWorker) {
  console
.log
(`I am worker #
${cluster.worker.id}`);
}const
 cluster = require
('node:cluster');

if
 (cluster.isPrimary) {
  console
.log
('I am primary');
  cluster.fork();
  cluster.fork();
} else
 if
 (cluster.isWorker) {
  console
.log
(`I am worker #
${cluster.worker.id}`);
}

`cluster.workers`#

Added in: v0.7.0

<Object>

A hash that stores the active worker objects, keyed by id field. This makes it
easy to loop through all the workers. It is only available in the primary
process.

A worker is removed from cluster.workers after the worker has disconnected
and exited. The order between these two events cannot be determined in
advance. However, it is guaranteed that the removal from the cluster.workers
list happens before the last 'disconnect' or 'exit' event is emitted.

import
 cluster from
 'node:cluster';

for
 (const
 worker of
 Object
.values
(cluster.workers)) {
  worker.send
('big announcement to all workers');
}const
 cluster = require
('node:cluster');

for
 (const
 worker of
 Object
.values
(cluster.workers)) {
  worker.send
('big announcement to all workers');
}

Cluster | Node.js v20.1.0 Documentation

How it works#

Class: Worker#

Event: 'disconnect'#

Event: 'error'#

Event: 'exit'#

Event: 'listening'#

Event: 'message'#

Event: 'online'#

worker.disconnect()#

worker.exitedAfterDisconnect#

worker.id#

worker.isConnected()#

worker.isDead()#

worker.kill([signal])#

worker.process#

worker.send(message[, sendHandle[, options]][, callback])#

Event: 'disconnect'#

Event: 'exit'#

Event: 'fork'#

Event: 'listening'#

Event: 'message'#

Event: 'online'#

Event: 'setup'#

cluster.disconnect([callback])#

cluster.fork([env])#

cluster.isMaster#

cluster.isPrimary#

cluster.isWorker#

cluster.schedulingPolicy#

cluster.settings#

cluster.setupMaster([settings])#

cluster.setupPrimary([settings])#

cluster.worker#

cluster.workers#

Class: `Worker`#

Event: `'disconnect'`#

Event: `'error'`#

Event: `'exit'`#

Event: `'listening'`#

Event: `'message'`#

Event: `'online'`#

`worker.disconnect()`#

`worker.exitedAfterDisconnect`#

`worker.id`#

`worker.isConnected()`#

`worker.isDead()`#

`worker.kill([signal])`#

`worker.process`#

`worker.send(message[, sendHandle[, options]][, callback])`#

Event: `'disconnect'`#

Event: `'exit'`#

Event: `'fork'`#

Event: `'listening'`#

Event: `'message'`#

Event: `'online'`#

Event: `'setup'`#

`cluster.disconnect([callback])`#

`cluster.fork([env])`#

`cluster.isMaster`#

`cluster.isPrimary`#

`cluster.isWorker`#

`cluster.schedulingPolicy`#

`cluster.settings`#

`cluster.setupMaster([settings])`#

`cluster.setupPrimary([settings])`#

`cluster.worker`#

`cluster.workers`#