Amazon SWF Quotas - Amazon Simple Workflow Service
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China.

Amazon SWF Quotas

Amazon SWF places quotas on the sizes of certain workflow parameters, such as on the number of domains per account and on the size of the workflow execution history. These quotas are designed to prevent erroneous workflows from consuming all of the resources of the system, but are not hard limits. If you find that your application is frequently exceeding these quotas, you can request a service quota increase.

General Account Quotas for Amazon SWF

  • Maximum registered domains – 100

    This quota includes both registered and deprecated domains.

  • Maximum workflow and activity types – 10,000 each per domain

    This quota includes both registered and deprecated types.

  • API call quota – Beyond infrequent spikes, applications may be throttled if they make a large number of API calls in a very short period of time.

  • Maximum request size – 1 MB per request

    This is the total data size per Amazon SWF API request, including the request header and all other associated request data.

  • Truncated responses for Count APIs – Indicates that an internal quota was reached and that the response is not the full count.

    Some queries will internally reach the 1 MB quota mentioned above before returning a full response. The following can return a truncated response instead of the full count.

    For each of these, if the truncated response is set to true, the count is less than the full amount. This internal quota can not be increased.

  • Maximum number of tags – 50 tags per resource.

    Attempting to add tags beyond 50 will result in a 400 error, TooManyTagsFault.

Quotas on Workflow Executions

  • Maximum open workflow executions – 100,000 per domain

    This count includes child workflow executions.

  • Maximum workflow execution time – 1 year

  • Maximum workflow execution history size – 25,000 events

    Best practice is to structure each workflow such that its history does not grow beyond 10,000 events. Since the decider has to fetch the workflow history, a smaller history allows the decider to complete more quickly. If using the Flow Framework, you can use ContinueAsNew to continue a workflow with a fresh history.

  • Maximum open child workflow executions – 1,000 per workflow execution

  • Workflow execution idle time quota – 1 year (constrained by workflow execution time maximum)

    You can configure workflow timeouts to cause a timeout event to occur if a particular stage of your workflow takes too long.

  • Workflow retention time quota – 90 days

    After this time, the workflow history can no longer be retrieved or viewed. There is no further limit to the number of closed workflow executions that are retained by Amazon SWF.

If your use case requires you to go beyond these quotas, you can use features Amazon SWF provides to continue executions and structure your applications using child workflow executions. If you find that you still need a quota increase, see Requesting a Quota Increase.

Quotas on Task Executions

  • Maximum pollers per task list – 1,000 per task list

    You can have a maximum of 1,000 pollers which simultaneously poll a particular task list. If you go over 1,000, you receive a LimitExceededException.


    While the maximum is 1,000, you might encounter LimitExceededException errors well before this quota. To reduce these errors, use multiple task lists to distribute polling.

  • Maximum tasks scheduled per second – 2,000 per task list

    You can schedule a maximum of 2,000 tasks per second on a particular task list. If you exceed 2,000, your ScheduleActivityTask decisions will fail with ACTIVITY_CREATION_RATE_EXCEEDED error.


    While the maximum is 2,000, you might encounter ACTIVITY_CREATION_RATE_EXCEEDED errors well before this quota. To reduce these errors, use multiple task lists to distribute the load.

  • Maximum task execution time – 1 year (constrained by workflow execution time maximum)

    You can configure activity timeouts to cause a timeout event to occur if a particular stage of your activity task execution takes too long.

  • Maximum time SWF will keep a task in the queue – 1 year (constrained by workflow execution time quota)

    You can configure default activity timeouts during activity registration that will cause a timeout event to occur if a particular stage of your activity task execution takes too long. You can also override the default activity timeouts when you schedule an activity task in your decider code.

  • Maximum open activity tasks – 1,000 per workflow execution.

    This quota includes both activity tasks that have been scheduled and those being processed by workers.

  • Maximum open timers – 1,000 per workflow execution

  • Maximum input/result data size – 32,768 characters

    This quota affects activity or workflow execution result data, input data when scheduling activity tasks or workflow executions, and input sent with a workflow execution signal.

  • Maximum decisions in a decision task response – varies

    Due to the 1 MB quota on the maximum API request size, the number of decisions returned in a single call to RespondDecisionTaskCompleted will be limited according to the size of the data used by each decision, including the size of any input data provided to scheduled activity tasks or to workflow executions.

Amazon SWF throttling quotas

In addition to the service quotas described previously, certain Amazon SWF API calls and decision events are throttled to maintain service bandwidth, using a token bucket scheme. If your rate of requests consistently exceeds the rates that are listed here, you can request a throttle quota increase.

The throttling and decision quotas are same across all regions.

Throttling quotas for all Regions

API name Bucket size Refill rate per second
CountClosedWorkflowExecutions 2000 6
CountOpenWorkflowExecutions 2000 6
CountPendingActivityTasks 200 6
CountPendingDecisionTasks 200 6
DeprecateActivityType 200 6
DeprecateDomain 100 6
UndeprecateDomain 100 6
DeprecateWorkflowType 200 6
UndeprecateWorkflowType 200 6
DeleteWorkflowType 200 6
DescribeActivityType 2000 6
DescribeDomain 200 6
DescribeWorkflowExecution 2000 6
DescribeWorkflowType 2000 6
GetWorkflowExecutionHistory 2000 60
ListActivityTypes 200 6
ListDomains 100 6
ListClosedWorkflowExecutions 200 6
ListOpenWorkflowExecutions 200 48
ListWorkflowTypes 200 6
PollForActivityTask 2000 200
PollForDecisionTask 2000 200
RecordActivityTaskHeartbeat 2000 160
RegisterActivityType 200 60
RegisterDomain 100 6
RegisterWorkflowType 200 60
RequestCancelWorkflowExecution 2000 30
RespondActivityTaskCompleted 2000 200
RespondActivityTaskCanceled 2000 200
RespondActivityTaskFailed 2000 200
RespondDecisionTaskCompleted 2000 200
SignalWorkflowExecution 2000 30
StartWorkflowExecution 2000 200
TerminateWorkflowExecution 2000 60
UndeprecateActivityType 200 6
TagResource 50 30
UntagResource 50 30
ListTagsForResource 50 30
StartActivityTask 500 200
DeleteWorkflowType 200 6

Decision quotas for all Regions

API name Bucket size Refill rate per second
RequestCancelExternalWorkflowExecution 1200 120
ScheduleActivityTask 500 200
SignalExternalWorkflowExecution 1200 120
StartChildWorkflowExecution 500 12
StartTimer 2000 200

Requesting a Quota Increase

Use the Support Center page in the Amazon Web Services Management Console to request a quota increase for resources provided by Amazon Simple Workflow Service. For more information, see To Request a Quota Increase in the Amazon General Reference.