Firebase Cloud Function:How many concurrent invocations a single HTTP trigger type function can have at any given time?

Question

From the doc in "Rate Limit" section, calls are restricted to 16 invocations per 100 seconds. But I am not sure if it is saying about onRequest/onCall HTTP triggers. That limit seems to be related to some CLI deployment or "testing via Firebase Console" (whatever that means) and not a call from client mobile sdk. If the restriction is legitimate, then that seems too limiting for something that is advertised to scale to potentially "millions/billions". I have a use case where 500 or so mobile users will be calling an HTTP end point which will perform a mixture of read/write to Firestore + some processing at a moment notice.

Answer 1

The "rate limits" table here mentions 16 invocations per 100 seconds, but the table is actually referring to usage limits on invoking the Cloud functions API to list/deploy cloud functions in a firebase project. Not invocation limits on the actual cloud fuctions which are much more generous.

The rate limits for background functions such as firebase event handlers (onCreate, onUpdate, etc) or PubSub scheduled functions, etc are 3000 concurrent invocations (for a function that takes 100 seconds to execute).

The rate limits for HTTP onCall functions are unlimited, at the moment. They simply scale up to accommodate higher traffic.

Background functions have additional limits, as explained below. These limits do not apply to HTTP functions

Here's a screenshot from cloud functions quota page