NodeBB periodically hangs every few hours, requiring me to restart the server. No error messages are listed in the NodeBB log or the MongoDB log. I can't reproduce the error.
What causes this? Is there a tool one can use to detect this and automatically restart the server?
You aren't alone here. I've been dealing with the same thing. It weird because the supervisor service still sees it as online, but nginx returns a 502. I have yet to find a good way to deal with this. It seems to have started on 1.0.3, so I've been considering going back down to 1.0.2.
Best regards
Bent
i3-2130/3240 3.4 GHz+ | 8 GB Ram
server {
listen 80;
server_name domain.com www.domain.com;
return 301 https://www.domain.com/$request_uri;
}
server {
ssl_certificate /etc/letsencrypt/live/www.domain.com/fullchain.pem;
ssl_certificate_key /etc/letsencrypt/live/www.domain.com/privkey.pem;
listen 443 ssl;
add_header Strict-Transport-Security "max-age=31536000";
server_name www.domain.com;
location / {
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_set_header X-NginX-Proxy true;
proxy_pass http://127.0.0.1:4567/;
proxy_ssl_session_reuse off;
proxy_redirect off;
# Socket.IO Support
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
}
Are you using the stable v1.0.3 or master?
@yariplus Good question. I'm honestly not sure. I just followed the install directions. I think I'm on the stable. :3 Is there an easy way to tell? My logs just say "Initializing NodeBB v1.0.3".
@L33t git rev-parse HEAD
@pichalite That'd work if I didn't just scp it to another server. 
Try grep -c filter:hotswap src/webserver.js
if it says 0, you are on stable.
We see similar issues. Sometimes we have to restart many times per day, some days it will keep going. we've been tracking it here:
We're running stuff under docker, which makes things more complicated, but I've had luck in a local dev/test environment with using Linux perf tools and building flamegraphs. For raisins, we haven't done this yet in docker, though you can see how to make that work here.
However, if you're not running docker, it's a little bit easier. Follow the instructions here:
He doesn't go into it there, but if you're on Ubuntu you'll need to install:
linux-tools-commonlinux-cloud-tools-common...and then kernel specific versions of those based on what you're running in order to use perf.
If you get there before we do, I'm eager to hear what anyone discovers with this.
@yariplus I'm on stable.
@boomzilla Thanks for the info. I'm on CentOS and not using docker. I'll take a look at that sometime soon. It's late thought and it's been a long day.
This is pretty hacky but it's worked beautifully so far: I wrote a Ruby script that tries to load my page. If it fails, it restarts the server. This is run in a cron job every minute. Here's my code:
require 'net/http'
begin
print "Downloading the page..."
res = Net::HTTP.start("yourdomainhere.com", :read_timeout => 5)
res.get('/')
puts " success!"
rescue Net::ReadTimeout => e
print " failed.\n\nRestarting the server..."
`./nodebb restart`
puts " success!"
end
Until the cause of this is figured out, this or something like it might be a good enough workaround. It sure beats me manually restarting it after my users throw a fit.
@LukeLaupheimer That's beautifully terrible. Once it crashes again and I (maybe) get some useful info.. I'll do something like that.
I don't ruby. Is that a loop? Or do I need to set a cron to run it every x minutes? Also.. my http is a 301 to https. Will that work with https also?
@L33t I set up a cron job so that it wouldn't be subject to the server resetting. I wanted it to be somewhat resilient in spite of its hackiness.
That said, this is just treating a symptom. I absolutely do not advocate for this approach on a permanent basis, only until the true cause has been revealed and addressed. It's the software engineers' equivalent of filling a hole in a dam with a big wad of gum. It buys you time. It doesn't solve the real issue.
In my case the issue was with an old version of Nodejs. Try to update it.
After update to latest node.js version, everything works fine. I recommend use nvm for switching between node.js versions.
Cool NVM, something learned every day Good to know for dev sites!
Bad news is that I crashed with absolutely no errors a few minutes ago. The good news is that it actually recovered on it's on in dev mode. I'll try updating nodejs as recommended.
Looks like moving to the latest node.js did not help. Just happened again.
We're running our instance with --perf-basic-prof-only-functions now and are able to generate flamegraphs. Just waiting for the servercooties to strike now...
Example flamegraph:
