(3.5.0 and earlier) DCV virtual session on Ubuntu 20.04 might show a black screen

The issue

ParallelCluster 3.5.0 and earlier versions are impacted by a known issue with DCV 2022.1-13300 and earlier, which intermittently causes a blank (black) screen in virtual sessions on Ubuntu 20.04. The issue triggers at the start of a virtual session due to a race condition, therefore it may happen for some virtual sessions and not others.

Affected versions

• ParallelCluster version 3.5.0 and earlier are impacted.

Mitigation

Upgrading DCV on the head node solves the problem. Below is a guide for upgrading DCV for your reference:

1. SSH into the head node of the affected cluster:

pcluster ssh --cluster-name <cluster-name>

2. List active DCV sessions

dcv list-sessions

3. Close running DCV sessions (You may need to run the command multiple times if there are multiple sessions)

dcv close-session <session-id>

4. Upgrade DCV (You can simply run the following script on Head Node, or learn more at https://docs.aws.amazon.com/dcv/latest/adminguide/setting-up-installing-linux-server.html#linux-server-install).

Paste the following script into a file install.sh and make it executable and run it. Remember to enter Y to install the new version during the installation

#!/bin/bash -ex

WORK_DIR=`mktemp -d`
DCV_VERSION=2022.2-14521
DCV_FILE=nice-dcv-${DCV_VERSION}-ubuntu2004-x86_64

function cleanup {
  rm -rf ${WORK_DIR}
}

trap cleanup EXIT

chmod go+rx ${WORK_DIR}
pushd ${WORK_DIR}
wget https://d1uj6qtbmh3dt5.cloudfront.net/NICE-GPG-KEY
gpg --import NICE-GPG-KEY
wget https://d1uj6qtbmh3dt5.cloudfront.net/2022.2/Servers/${DCV_FILE}.tgz
tar -xvzf ${DCV_FILE}.tgz
pushd ${DCV_FILE}


sudo mv /etc/dcv/dcv.conf /etc/dcv/dcv.conf.bak
sudo systemctl stop dcvserver
sudo systemctl disable dcvserver
/usr/bin/yes | sudo apt install -y ./nice-dcv-server_2022.2.14521-1_amd64.ubuntu2004.deb
sudo apt install -y ./nice-dcv-web-viewer_2022.2.14521-1_amd64.ubuntu2004.deb
sudo usermod -aG video dcv
sudo apt install -y ./nice-xdcv_2022.2.519-1_amd64.ubuntu2004.deb
# if the instance is a GPU instance, uncomment the following line
# sudo apt install -y ./nice-dcv-gl_2022.2.1012-1_amd64.ubuntu2004.deb
sudo mv /etc/dcv/dcv.conf.bak /etc/dcv/dcv.conf
sudo systemctl restart dcvserver
sudo systemctl enable dcvserver

popd
popd