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The React Native SDK lets you batch events and includes options to set a maximum batch size and flush interval timeout. The benefit of event batching is less network traffic for the same number of impression and conversion events tracked. By default, event batching is enabled in React SDK.

The event batching functionality works by processing impression events from [OptimizelyExperiment](🔗) or [OptimizelyFeature](🔗), and conversion events from calling track on the client instance, placing them into a queue. The queue is drained when it either reaches its maximum size limit or when the flush interval is triggered.

The event batching functionality provides support for asynchronous, offline event batching in React Native applications. The events dispatched while the device was offline are stored in a persistent cache on user's device. The failed events are then re-dispatched when:

  • Internet connectivity is restored.

  • A new event is ready to be dispatched.

  • SDK is initialized the next time.

Note

Event batching works with both out-of-the-box and custom event dispatchers.

The event batching process does not remove any personally identifiable information (PII) from events. You must still ensure that you aren't sending any unnecessary PII to Optimizely.

## Configure event batching

We provide three options to configure event batching: `eventBatchSize` , `eventFlushInterval` and `eventMaxQueueSize`. You can pass in all the options during client creation. Events are held in a queue until either:

  • The number of events reaches the defined `eventBatchSize`.

  • The oldest event has been in the queue for longer than the defined `eventFlushInterval`, which is specified in milliseconds. The queue is then flushed and all queued events are sent to Optimizely in a single network request.

  • A new datafile revision is received. This occurs only when live datafile updates are enabled.

For the React Native users, `eventMaxQueueSize` represents the maximum number of events that can be stored in the persistent cache when the device is offline.



The table below defines these options and their default values.
NameDescription
**eventBatchSize** The maximum number of events to hold in the queue. Once this number is reached, all queued events are flushed and sent to Optimizely.
Default: 10

**Note**: By setting this value to 1, events aren't batched and event requests behave exactly as in pre-3.3.0 JavaScript and Node SDKs.
**eventFlushInterval** The maximum duration in milliseconds that an event can exist in the queue before being flushed.
Default: 1000 ms
**eventMaxQueueSize**The maximum number of event batches stored in persistent cache on a user's device when the events fail to dispatch because there is no Internet connectivity. The size of each batch stored is determined by `eventBatchSize`.  As soon as you regain connectivity, all batches are flushed (bypassing `eventFlushInterval`).
Default: 10000
Note
The maximum payload size is 3.5 MB. If the resulting batch payload exceeds this limit, requests will be rejected with a 400 response code, `Bad Request Error`.
## Close Optimizely on application exit
If you enable event batching, it is important that you call the Close method (`optimizely.close()`) prior to exiting. This ensures that queued events are flushed as soon as possible to avoid any data loss.
Important
Because the Optimizely client maintains a buffer of queued events, you must call `close()` on the Optimizely instance before shutting down your application or whenever dereferencing the instance.
MethodDescription
**close()** Stops all timers and flushes the event queue. This method will also stop any timers that are happening for the datafile manager.

**Note**: We recommend that you connect this method to a kill signal for the running process.