Deploy NodeJS app with pm2 and Capistrano - node.js

Question

I develop project based on NodeJs, pm2, Capistrano 3.
Faced with problem of downtime while deploying Node app with Capistrano.
deploy.rb:
set :linked_dirs, ['node_modules', 'logs']
set :linked_files, ['ecosystem.json']
set :npm_flags, '--silent --no-spin'
before 'deploy:updated', 'assets:upload'
after 'deploy:updated', 'assets:webpack'
after 'deploy:publishing', 'pm2:restart'
assets:upload - builds js and css files and uploads to CDN. Build performs with Webpack so it's create webpack-assets.json.
assets:webpack - uploads webpack-assets.json to prod servers. webpack-assets.json is using by node to get exact asset name because it contains hash:
task :webpack do
run_locally do
roles(:web).each do |host|
execute :rsync, '-rvzu', "themes-assets.json", "#{host.user}##{host.hostname}:#{fetch(:release_path)}"
execute :rsync, '-rvzu', "webpack-assets.json", "#{host.user}##{host.hostname}:#{fetch(:release_path)}"
end
end
end
pm2:restart - should perform zero time reload. But in fact I'm getting 1second down time. If I perform this task independently there is no downtime.
def restart_app
within current_path do
execute :pm2, :startOrRestart, fetch(:deploy_to) + '/shared/ecosystem.json'
end
end
pm2 logs show the following error
Process with pid 123169 still not killed, retrying...

Answer 1

Instead of
pm2 startOrRestart <app|conf>
You have to use
pm2 startOrReload <app|conf>
If you still see a downtime while using "startOrReload", have a look at: http://pm2.keymetrics.io/docs/usage/signals-clean-restart/#graceful-start