Isolate class Null safety

An isolated Dart execution context.

All Dart code runs in an isolate, and code can access classes and values only from the same isolate. Different isolates can communicate by sending values through ports (see ReceivePort, SendPort).

An Isolate object is a reference to an isolate, usually different from the current isolate. It represents, and can be used to control, the other isolate.

When spawning a new isolate, the spawning isolate receives an Isolate object representing the new isolate when the spawn operation succeeds.

Isolates run code in its own event loop, and each event may run smaller tasks in a nested microtask queue.

An Isolate object allows other isolates to control the event loop of the isolate that it represents, and to inspect the isolate, for example by pausing the isolate or by getting events when the isolate has an uncaught error.

The controlPort identifies and gives access to controlling the isolate, and the pauseCapability and terminateCapability guard access to some control operations. For example, calling pause on an Isolate object created without a pauseCapability, has no effect.

The Isolate object provided by a spawn operation will have the control port and capabilities needed to control the isolate. New isolate objects can be created without some of these capabilities if necessary, using the Isolate.Isolate constructor.

An Isolate object cannot be sent over a SendPort, but the control port and capabilities can be sent, and can be used to create a new functioning Isolate object in the receiving port's isolate.


Isolate(SendPort controlPort, {Capability? pauseCapability, Capability? terminateCapability})
Creates a new Isolate object with a restricted set of capabilities.


controlPort SendPort
Control port used to send control messages to the isolate.
debugName String?
The name of the Isolate displayed for debug purposes.
@Since("2.3"), read-only
errors Stream
Returns a broadcast stream of uncaught errors from the isolate.
hashCode int
The hash code for this object.
read-only, inherited
pauseCapability Capability?
Capability granting the ability to pause the isolate.
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited
terminateCapability Capability?
Capability granting the ability to terminate the isolate.


addErrorListener(SendPort port) → void
Requests that uncaught errors of the isolate are sent back to port.
addOnExitListener(SendPort responsePort, {Object? response}) → void
Requests an exit message on responsePort when the isolate terminates.
kill({int priority = beforeNextEvent}) → void
Requests the isolate to shut down.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed.
pause([Capability? resumeCapability]) Capability
Requests the isolate to pause.
ping(SendPort responsePort, {Object? response, int priority = immediate}) → void
Requests that the isolate send response on the responsePort.
removeErrorListener(SendPort port) → void
Stops listening for uncaught errors from the isolate.
removeOnExitListener(SendPort responsePort) → void
Stops listening for exit messages from the isolate.
resume(Capability resumeCapability) → void
Resumes a paused isolate.
setErrorsFatal(bool errorsAreFatal) → void
Sets whether uncaught errors will terminate the isolate.
toString() String
A string representation of this object.


operator ==(Object other) bool
The equality operator.

Static Properties

current Isolate
An Isolate object representing the current isolate.
packageConfig Future<Uri?>
The location of the package configuration of the current isolate, if any.

Static Methods

exit([SendPort? finalMessagePort, Object? message]) → Never
Terminates the current isolate synchronously.
resolvePackageUri(Uri packageUri) Future<Uri?>
Maps a package: URI to a non-package Uri.
spawn<T>(void entryPoint(T message), T message, {bool paused = false, bool errorsAreFatal = true, SendPort? onExit, SendPort? onError, String? debugName}) Future<Isolate>
Creates and spawns an isolate that shares the same code as the current isolate.
spawnUri(Uri uri, List<String> args, dynamic message, {bool paused = false, SendPort? onExit, SendPort? onError, bool errorsAreFatal = true, bool? checked, Map<String, String>? environment, Uri? packageRoot, Uri? packageConfig, bool automaticPackageResolution = false, String? debugName}) Future<Isolate>
Creates and spawns an isolate that runs the code from the library with the specified URI.


beforeNextEvent → const int
Argument to ping and kill: Ask for action before the next event.
immediate → const int
Argument to ping and kill: Ask for immediate action.