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Interface: WorkerOptions


Options to configure the Worker



Optional activities: object

Mapping of activity name to implementation


Optional buildId: string

A string that should be unique to the exact worker code/binary being executed.

This is used to populate the binaryChecksum attribute in history events originated from this Worker.


@temporalio/worker package name and version + checksum of workflow bundle's code


Optional bundlerOptions: Object

Type declaration

ignoreModules?string[]List of modules to be excluded from the Workflows bundle. Use this option when your Workflow code references an import that cannot be used in isolation, e.g. a Node.js built-in module. Modules listed here MUST not be used at runtime. > NOTE: This is an advanced option that should be used with care.
webpackConfigHook?(config: Configuration) => ConfigurationBefore Workflow code is bundled with Webpack, webpackConfigHook is called with the Webpack configuration object so you can modify it.


Optional connection: NativeConnection

A connected NativeConnection instance.

If not provided, the worker will default to connect insecurely to localhost:7233.


Optional dataConverter: DataConverter

Provide a custom DataConverter.


Optional debugMode: boolean

If true Worker runs Workflows in the same thread allowing debugger to attach to Workflow instances.

Workflow execution time will not be limited by the Worker in debugMode.




Optional defaultHeartbeatThrottleInterval: string | number

Default interval for throttling activity heartbeats in case ActivityOptions.heartbeat_timeout is unset. When the timeout is set in the ActivityOptions, throttling is set to heartbeat_timeout * 0.8.


number of milliseconds or ms-formatted string


30 seconds


Optional enableNonLocalActivities: boolean

Whether or not to poll on the Activity task queue.

If disabled and activities are registered on the Worker, it will run only local Activities.




Optional enableSDKTracing: boolean

Enable opentelemetry tracing of SDK internals like polling, processing and completing tasks.

Useful for debugging issues with the SDK itself.

For completeness the Rust Core also generates opentelemetry spans which connect to the Worker's spans. Configure CoreOptions.telemetryOptions to enable tracing in Core.




Optional identity: string

A human-readable string that can identify your worker




Optional interceptors: WorkerInterceptors

A mapping of interceptor type to a list of factories or module paths.

By default, ActivityInboundLogInterceptor and WorkflowInboundLogInterceptor are installed. If you wish to customize the interceptors while keeping the defaults, use appendDefaultInterceptors.

When using workflowBundle, these Workflow interceptors (WorkerInterceptors.workflowModules) are not used. Instead, provide them via workflowInterceptorModules when calling bundleWorkflowCode.


Optional maxActivitiesPerSecond: number

Limits the number of activities per second that this worker will process. The worker will not poll for new activities if by doing so it might receive and execute an activity which would cause it to exceed this limit. Must be a positive floating point number.

If unset, no rate limiting will be applied to Worker's activities. (tctl task-queue describe will display the absence of a limit as 100,000.)


Optional maxCachedWorkflows: number

The number of Workflow isolates to keep in cached in memory

Cached Workflows continue execution from their last stopping point. If the Worker is asked to run an uncached Workflow, it will need to replay the entire Workflow history. Use as a dial for trading memory for CPU time.

Most users are able to fit at least 250 Workflows per GB of available memory. The major factors contributing to a Workflow's memory weight are the size of allocations made by the Workflow itself and the size of the Workflow bundle (code and source map). For the SDK test Workflows, we managed to fit 750 Workflows per GB.


max(maxHeapMemory / 1GiB - 1, 1) * 250


Optional maxConcurrentActivityTaskExecutions: number

Maximum number of Activity tasks to execute concurrently. Adjust this to improve Worker resource consumption.




Optional maxConcurrentLocalActivityExecutions: number

Maximum number of Activity tasks to execute concurrently. Adjust this to improve Worker resource consumption.




Optional maxConcurrentWorkflowTaskExecutions: number

Maximum number of Workflow tasks to execute concurrently. Adjust this to improve Worker resource consumption.




Optional maxHeartbeatThrottleInterval: string | number

Longest interval for throttling activity heartbeats


number of milliseconds or ms-formatted string


60 seconds


Optional maxTaskQueueActivitiesPerSecond: number

Sets the maximum number of activities per second the task queue will dispatch, controlled server-side. Note that this only takes effect upon an activity poll request. If multiple workers on the same queue have different values set, they will thrash with the last poller winning.

If unset, no rate limiting will be applied to the task queue.


Optional namespace: string

The namespace this worker will connect to




Optional reuseV8Context: boolean

Toggle whether to reuse a single V8 context for the workflow sandbox.

Context reuse significantly decreases the amount of resources taken up by workflows. From running basic stress tests we've observed 2/3 reduction in memory usage and 1/3 to 1/2 in CPU usage with this feature turned on.

This feature is experimental and requires further testing before it can be considered stable or made default.

Introduced in SDK version 1.6.0


Optional showStackTraceSources: boolean

Whether or not to send the sources in enhanced stack trace query responses




Optional shutdownForceTime: string | number

Time to wait before giving up on graceful shutdown and forcefully terminating the worker.

After this duration, the worker will throw GracefulShutdownPeriodExpiredError and any running activities and workflows will not be cleaned up. It is recommended to exit the process after this error is thrown.

Use this option if you must guarantee that the worker eventually shuts down.


number of milliseconds or ms-formatted string


Optional shutdownGraceTime: string | number

Time to wait for pending tasks to drain after shutdown was requested.

In-flight activities will be cancelled after this period and their current attempt will be resolved as failed if they confirm cancellation (by throwing a CancelledFailure or AbortError).


number of milliseconds or ms-formatted string




Optional sinks: InjectedSinks<any>

Implementation of the Sinks interface, a mapping of name to InjectedSink.

Sinks are a mechanism for exporting data from the Workflow sandbox to the Node.js environment, they are necessary because the Workflow has no way to communicate with the outside World.

Sinks are typically used for exporting logs, metrics and traces out from the Workflow.

Sink functions may not return values to the Workflow in order to prevent breaking determinism.

By default the defaultWorkerLogger sink is installed and is required by WorkflowInboundLogInterceptor.

If you wish to customize the sinks while keeping the defaults, merge yours with defaultSinks.


Optional stickyQueueScheduleToStartTimeout: string

How long a workflow task is allowed to sit on the sticky queue before it is timed out and moved to the non-sticky queue where it may be picked up by any worker.


number of milliseconds or ms-formatted string




taskQueue: string

The task queue the worker will pull from


Optional workflowBundle: WorkflowBundleOption

Use a pre-built bundle for Workflow code. Use bundleWorkflowCode to generate the bundle. The version of @temporalio/worker used when calling bundleWorkflowCode must be the exact same version used when calling Worker.create.

This is the recommended way to deploy Workers to production.

See for more information.

When using this option, workflowsPath, bundlerOptions and any Workflow interceptors modules provided in * interceptors are not used. To use workflow interceptors, pass them via workflowInterceptorModules when calling bundleWorkflowCode.


Optional workflowsPath: string

Path to look up workflows in, any function exported in this path will be registered as a Workflows in this Worker.

If this option is provided to create, Webpack compliation will be triggered.

This option is typically used for local development, for production it's preferred to pre-build the Workflow bundle and pass that to create via the workflowBundle option.

See for more information.