Face API calls slow down

Joseph Lee 1

I have writing a c# program to compare faces in 2 URLs (3 calls per compare)

It works but when I start to run 300 comparisons, it slow than at around 200 calls. Initial it can do 2 compare (6 calls) per second but then suddenly drop to few seconds per compare, but no error arise.

I am using trial subscription and using standard S0 as I have free US$200 quota. Is that related?

Thanks.

GiftA-MSFT 11,151 Reputation points

2022-03-30T17:18:19.877+00:00

Hi, thanks for reaching out. According to the documentation, S0 tier has a limit of 10 transactions per second. A transaction is a single API call. Hope this helps.
Joseph Lee 1 Reputation point

2022-03-31T15:37:19.857+00:00

I understand the limit is 10 TPS, but my question is why in my experience, it drops from 6 TPS to less than 1 TPS after around 500-600 calls. and it is sharply decrease, like hitting a boundary
GiftA-MSFT 11,151 Reputation points

2022-03-31T16:17:07.127+00:00

Are these calls happening in parallel?

Joseph Lee 1

private async Task<VerifyResult> Verify(IFaceClient faceClient, string url1, string url2, string recognition_model)
{
    var faces_1 = faceClient.Face.DetectWithUrlAsync(url1, recognitionModel: recognition_model, detectionModel: DetectionModel.Detection03);
    var faces_2 = faceClient.Face.DetectWithUrlAsync(url2, recognitionModel: recognition_model, detectionModel: DetectionModel.Detection03);
    Task.WaitAll(new Task<IList<DetectedFace>>[] { faces_1, faces_2 });
    return await faceClient.Face.VerifyFaceToFaceAsync((Guid)faces_1.Result[0].FaceId, (Guid)faces_2.Result[0].FaceId);
}

main()
{
    for (int i = 0; i < count; i++)
    {
        VerifyResult result = await Verify(client, url[i].url1, url[i].url2, RECOGNITION_MODEL4);
        if (result != null)
        {
            wks.Cells[2 + i, ColSame] = result.IsIdentical ? "Yes" : "No";
            wks.Cells[2 + i, ColConfidence] = result.Confidence;
        }
    }
}