“workspace in use or cannot be created” in eclipse or nvidia nsight

– remove .lock file in workspace’s metadata folder.
rm {YourWorkspaceDir}/.metadata/.lock

– find out the RECENT_WORKSPACES attribute
cd ~/.eclipse
grep -r "RECENT_WORKSPACES" *

– once you got the file where the RECENT_WORKSPACES attribute exists, edit that file by removing the RECENT_WORKSPACES line.