Race Conditions

A race condition is a concept where an outcome is dependent on the sequence or timing of other events. For example, if the desired sequence of events is “Event A” and then “Event B”, but sometimes “Event A” comes first and other times “Event B” comes first—that is known as a race condition.

In the Braze platform, one of the most common race conditions occurs with messages that target newly created users. Here, the expected order of events is: (1) a user gets created; (2) the same user is immediately targeted for a message. However, in some cases, the second event will trigger first. This means that a message is attempting to be sent to a user that has not been created yet, and as a result, the user never receives it.

If you’re using separate API endpoints to create users and trigger Canvases/campaigns, this can also result in this race condition. When user information is sent to Braze via the users/track endpoint, it may occasionally take a few seconds to process. As a result, when requests are made to the users/track and messaging endpoints at the same time, there is no guarantee that the user information will be updated before a message is sent. If these requests are made in the same API call, there should be no issue. Please note that if you are sending a scheduled message API call, these requests must be separate, and a user must be created before sending the schdeuled API call.

One way to avoid this race condition is by adding a delay—around a minute or so—between the creation of a user, and the targeting of that user by your Canvas or campaign.

Similarly, you can use the Attributes object to add/create/update a user, and then target them using either the canvas/trigger/send or campaign/trigger/send endpoint. This API call will process the Attributes object before targeting the users.

Attributes that are included in this object will be processed before Braze begins to send the campaign. If the send_to_existing_only flag is set to false, and an external_user_id does not exist in Braze’s database, Braze will create a user profile for the external_user_id and process the associated attributes to the user profile before Braze begins to send the campaign. Also note, if the send_to_existing_only flag is set to false, then the attributes object must be included in order to create the user.

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