Intermittent timeout with image preivews

My actions before raising this issue

• [X ] Read/searched the docs
• [X ] Searched past issues

Expected Behaviour

We have a docker-compose.overide that mounts the cvat_data to a nfs mount point. We expect that when we load any page that has a preview, the fetch request /api/v1/tasks/10/data?type=preview should return a successful fetch

Current Behaviour

When we load a page such as Tasks or Projects, there is a 10% success rate in successfully fetching any image previews. The fetch will take anywhere up to 60k ms and will timeout, to which the page will then finally load without any images, and will display ‘preview’ in it’s place.

This data is reachable and is fetched from this mounted point on a NAS.

Note that it will work perfectly for a while, then it suddenly stops working and becomes unusable.

Possible Solution

We’ve changed the way the drives are mounted multiple times (mounted to linux and fetched by directory verse mounted within the docker-compose) with no avail. It’s possible that it might be to do with the networking link between a NAS and the docker container, but could be some other internal bug.

Steps to Reproduce (for bugs)

1. Run the docker compose with the following override setup:

version: "3.3"

services:
  cvat_proxy:
    environment:
      CVAT_HOST: localhost
    ports:
      - "80:80"
  cvat:
    environment:
      CVAT_SHARE_URL: "Mounted from /home/gr directory"
    volumes:
      - cvat_share:/home/django/share:ro
volumes:
  cvat_share:
    driver_opts:
      type: "nfs"
      device: nas.local:/volume3/shared
      o: "addr=nas.local,nolock,soft,rw"

  cvat_data:
    driver_opts:
      type: "nfs"
      device:  ":/volume1/data"
      o: "addr=nas.local,nolock,soft,rw"

1. Create a new project
2. Create a new task using files from external cvat_share network
3. Open task.
4. Log out.
5. Close window and open new window
6. Login again
7. Keep loading various preview pages whilst monitoring network requests
8. Suddenly the page will take a long time to load, with the get request for the image previews for the project/task not responding. note sometimes it will use a cached response to display the preview images

Context

Just trying to get it working consistently

Your Environment

• Docker version docker version (e.g. Docker 17.0.05): 20.10.5
• Operating System and version (e.g. Linux, Windows, MacOS): Linux Ubuntu 20
• Other diagnostic information / logs: docker logs cvat

2021-03-25 23:26:15,023 DEBG 'ssh-agent' stderr output:
debug2: fd 4 setting O_NONBLOCK
debug1: process_message: socket 1 (fd=4) type 11

2021-03-25 23:28:52,336 DEBG 'runserver' stderr output:
[Thu Mar 25 23:28:52.336043 2021] [wsgi:error] [pid 365:tid 139864464013056] [remote 172.28.0.9:43938] WARNING - 2021-03-25 23:28:52,335 - environment - Failed to import module 'tf_detection_api_format.converter.py': Can't import tensorflow. Test process exit code: -4. This is likely because your CPU does not support AVX instructions, which are required for tensorflow.

2021-03-25 23:29:46,357 DEBG 'rqworker_low' stderr output:
DEBUG - 2021-03-25 23:29:46,357 - worker - Sent heartbeat to prevent worker timeout. Next one should arrive within 480 seconds.

2021-03-25 23:29:46,454 DEBG 'rqworker_default_1' stderr output:
DEBUG - 2021-03-25 23:29:46,453 - worker - Sent heartbeat to prevent worker timeout. Next one should arrive within 480 seconds.

2021-03-25 23:29:49,665 DEBG 'rqworker_default_0' stderr output:
DEBUG - 2021-03-25 23:29:49,664 - worker - Sent heartbeat to prevent worker timeout. Next one should arrive within 480 seconds.

2021-03-25 23:36:31,392 DEBG 'rqworker_low' stderr output:
DEBUG - 2021-03-25 23:36:31,389 - worker - Sent heartbeat to prevent worker timeout. Next one should arrive within 480 seconds.

2021-03-25 23:36:31,489 DEBG 'rqworker_default_1' stderr output:
DEBUG - 2021-03-25 23:36:31,488 - worker - Sent heartbeat to prevent worker timeout. Next one should arrive within 480 seconds.

2021-03-25 23:36:34,699 DEBG 'rqworker_default_0' stderr output:
DEBUG - 2021-03-25 23:36:34,698 - worker - Sent heartbeat to prevent worker timeout. Next one should arrive within 480 seconds.

Thanks for the help in advanced.

[natrad100]

use the getPreview() in the api server,

https://github.com/openvinotoolkit/cvat/blob/380f4d81612f45d071f9a4f70d407a5dd824d929/cvat-core/src/server-proxy.js#L782-L797

and before doing anything simply return an empty string.

            async function getPreview(tid) {
                return "";

That’s it!

[kosehy]

I will try your solution. Thank you for sharing!