Flushing chunked transfer when using Google Cloud Functions?

Question

exports.cloudFunctionEntryPoint = async (req, res) => {
    setTimeout(()=>{
        res.write("1\n");
    }, 1000)
    setTimeout(()=>{
        res.write("2\n");
    }, 2000)
    setTimeout(()=>{
        res.write("3\n");
    }, 3000)
    setTimeout(()=>{
        res.write("4\n");
    }, 4000)
    setTimeout(()=>{
        res.write("5\n");
        res.end();
    }, 5000)
}

When using a local expressjs server, the server would flush immediately on each res.write , so I can get the numbers on every second.

However on the GCF, data is flushed only when res.end() is called, so I can only get all numbers together at the 5th second.

Is there a way to make GCF to flush on each res.write ?

Answer 1

It's not possible. Cloud Functions buffers all of the output, up to a max 10MB, before it's sent to the client.

See also:

• Multiple returns on HTTP request in Firebase / Google Cloud Function