Cloud Functions 中的 Firebase Firestore 冷启动缓慢

Question

On a cold start (after deploying or after 3hrs) the function to request a document from Firestore takes an incredible amount of time which is different to when it's used rapidly.

Cold Start:

Function execution took 4593 ms, finished with status code: 200

Rapid fire (me sending using the same function over and over):

Function execution took 437 ms, finished with status code: 200

My code for getting the documents is quite simple:

function getWorkspaceDocument(teamSpaceId) {
    return new Promise((resolve, reject) => {
        var teamRef = db.instance.collection('teams').doc(teamSpaceId);
        teamRef.get().then(doc => {
            if (doc.exists) {
                resolve(doc.data());
                return;
            }
            else {
                reject(new Error("Document cant be found"));
                return;
            }
        }).catch(error => {
            reject(new Error("Document cant be found"));
        });
    });
}

I'm trying to make a Slack bot and the slow returns on Firebase Firestore throw time outs in Slacks API. Is there a way on Firebase to stop cold starts from happening and letting it persist through out?

Answer 1

If the cloud function needs to start a new instance your cold start time seems normal. This is one drawback of a serverless function.

I think there is a problem with your implementation. Could you show more details?

Here is a nice little video about this topic: https://youtu.be/v3eG9xpzNXM

Answer 2

Another thing I would suggest checking is the amount of memory allocated to a particular function. Each level selected increases non only the RAM, but the CPU frequency as well (and the costs, be careful and don't forget about the pricing calculator !). There is a direct dependency between the package size of your function and the cold-start (source: https://mikhail.io/serverless/coldstarts/gcp/ ).

I can see that you are using the Firestore admin package, which is not considered to be lightweight (source: https://github.com/firebase/firebase-admin-node/issues/238 ). Thus, 128MB configuration might not be enough.

For our project increasing the RAM from 128MB to 512MB decreased the cold boot 10x from 20 seconds to 2.5seconds on average. Be sure not to overlook this in case you have several dependencies (7 in our case).