[SavedModel] Please help me check for multithreading usage

TensorFlow General Discussion
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1

I am a newcomer to TensorFlow and I have a FasterRCNN savedmodel.

Recently, I am trying to load this model using Python for object detection.

Due to the large number of images that need to be detected every day, I try to use multithreading to call the model method, but I am not sure if I have written the code correctly because my server’s GPU usage is high, and my graphics card is NVIDIA A10 (16 vCPU, gpu-mem: 24GB).

The following is the code to load the model

import tensorflow as tf
from tensorflow import saved_model as sm

def init_model_for_target(od_target):
    rtn_val = False
    try:
        global g_model, g_model_fn
        time_init_start = time.time()
        model_with_signature_path = Config["OD_MODEL_DIR"][od_target]
        assert os.path.exists(model_with_signature_path), "od model not existed"
        g_model = sm.load(model_with_signature_path)
        g_model_fn = g_model.signatures[sm.DEFAULT_SERVING_SIGNATURE_DEF_KEY]
        logger.info(f"MAIN: init od model for [{od_target}], costs: {time.time() - time_init_start}")
        rtn_val = True
    except BaseException as e:
        logger.error(f"Exception: init od model for [{od_target}] failed, {e}")
    return rtn_val

And this is the code that calls the model

def run_inference_for_single_image(image):
    input_image = tf.convert_to_tensor(image)
    input_image = input_image[tf.newaxis, ...]
    input_true_image_shape = tf.reshape(tf.constant(image.shape, dtype=tf.int32, name="true_image_shape:0"), (1, 3))
    
    output_dict = g_model_fn(image=input_image, true_image_shape=input_true_image_shape)

    num_detections = int(output_dict.pop("num_detections"))
    output_dict = {key: value[0, :num_detections].numpy() for key, value in output_dict.items()}
    output_dict["num_detections"] = num_detections
    output_dict["detection_classes"] = output_dict["detection_classes"].astype(np.int64)
    return output_dict

def subthread02_load_image_and_detect(image_path, image_folder, image_name):
    from PIL import Image
    rtn_val = False; time_od_costs = 0
    res_dict = {"image_folder": image_folder, "image_name": image_name, "od_results": []}
    try:
        time_od_start = time.time()
        image_data = np.array(Image.open(image_path))
        od_res_dict = run_inference_for_single_image(image_data)
        time_od_costs = time.time() - time_od_start
        res_dict.update(od_results=od_res_dict)
        rtn_val = True
    except BaseException as e:
        logger.error(f"DETECT: Exception: {e}")
    return rtn_val, time_od_costs, res_dict

Finally, I submit multithreaded tasks like this (MAX_THREADS_DETECT = 3)

from concurrent.futures import ThreadPoolExecutor, as_completed
pool_detect = ThreadPoolExecutor(max_workers=MAX_THREADS_DETECT, thread_name_prefix=od_target + "_od")  
ls_future_detect = []
...
ls_future_detect.append(pool_detect.submit(subthread02_load_image_and_detect, pic_save_path, image_folder, image_name)
                        
for index, future in enumerate(as_completed(ls_future_all_detect)):
    is_success, time_od_costs, od_res_dict = future.result()
    ...

pool_detect.shutdown()

What I’m puzzled about is that my GPU usage is high, and my gpu-mem usage is also high. Is it because I didn’t write multithreaded code correctly? Or does FasterRCNN require high computational power?

3

Hi @Asterisk_Fang, Generally faster R-CNN are computationally expensive. The high GPU usage and memory usage could be due to the number of the images being processed, the batch size used for inference, and the complexity of the model architecture. Thank You.

1 Like
5

@Kiran_Sai_Ramineni
Hi, Kiran_Sai_Ramineni! Thank you very much for your reply. It has helped me a lot, but I still have some questions about it.

May I ask if the method for calling the model with multiple threads is appropriate? Because I am not very familiar with the use of multithreading, I am very concerned that my incorrect use has increased the unnecessary expenses of the GPU.

I attempted to deploy 2 pods on each of the three nodes to run my code. In your opinion, if the GPU load with 3 threads is so high, what is the appropriate number of threads?

Additionally, I am confused about the impact of the number of images on the GPU usage rate you mentioned. Why is it affected when only one image is processed at a time in a thread?

Due to the relatively fixed positions that need to be detected in the image, I would like to crop the image and retrain and use the model. Will this reduce the requirements for the GPU? Or will it only reduce the detection time?

Thank you very much for your patient answer! I would be very grateful if you could help me answer my doubts again.