Μηνιαία αρχεία: Απρίλιος 2021


Cloudflare: Error 522 – Connection timed out

Recently, we’ve been noticing weird behavior on sites that are proxied behind Cloudflare servers. While visiting a site from one internet connection, we are constantly getting a 522 error. If at that moment, we switch our internet connection on that machine and visit the same page, it works as expected.

We are sure that the servers we have access to did not run out of resources, nor does the firewall block Cloudflare IPs. All firewalls are properly configured to accept connections from the official Cloudflare IPs that were retrieved from here.

We will investigate it further, hopefully we will figure it out.


AttributeError: module ‘html5lib.treebuilders’ has no attribute ‘_base’

Recently, we were receiving the above error on a GNU/Linux Ubuntu 20.04 LTS.

AttributeError: module 'html5lib.treebuilders' has no attribute '_base'

We had installed beautifulsoup4 and html5lib using pip. To solve the issue, we had to uninstall the html5lib that was installed by pip and install it through apt.

# Remove html5lib if you have installed it with pip3:
pip3 uninstall html5lib;

pip3 install --upgrade beautifulsoup4
sudo apt-get install python3-html5lib

How to check if PyTorch is using the GPU?

The following basic code, will import PyTorch into a project and test if GPU capabilities are enabled and available.

import torch

# Should produce "True"
torch.cuda.is_available()

# Should produce the number of available devices, if you have one device it should produce the value "1"
torch.cuda.device_count()

# If there is a device and it is the first one, it should produce the "0"
torch.cuda.current_device()

# Assuming that there is at least one device, with the following two commands we will get some information on the first available device

# Should produce something similar to "<torch.cuda.device object at 0x7f12b1a298d0>"
torch.cuda.device(0)

# Should produce something similar to "'GeForce GTX 1050 Ti'"
torch.cuda.get_device_name(0)

We are using Ubuntu 20.04 LTS and the NVidia drivers were installed automatically during installation.


OpenCV error: the function is not implemented

Recently, we were working on a python 3 project that was using opencv. When we used conda defaults repository to install opencv it installed a 3.X.Y version which would produce the following error on PyCharm on Ubuntu 20.04 LTS:

pycharm cv2.error: OpenCV(3.4.2) highgui/src/window.cpp:710: error: (-2:Unspecified error) The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Carbon support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script in function 'cvStartWindowThread'

Following the instructions above, we installed the missing packages using sudo apt-get install libgtk2.0-dev pkg-config; with no change on the results. To fix the issue, we completely removed opencv from the stables repository and we installed version 4.5.1 from the conda-forge repository as follows:

conda remove opencv;
conda install -c conda-forge opencv=4.5.1;