16.04: some programs including Nautilus hang for 20 seconds before opening

I have a quite powerful Dell laptop with Ubuntu 16.04 installed.

Some times (I’d say, every 2 or 3 sessions) I have my entire session affected by a problem with some applications hanging or not starting at all. This is usually solved by rebooting (which isn’t ideal).

The most common way I realise that the current session is affected, is by trying to open a nautilus window (by clicking on the “Files” dock icon). The window will open, but only after ~20 seconds. Also if I try to launch a File dialog from within other programs (when doing File > Open or Mail > Attach), the file picker will appear after 20 second, freezing the parent program in the meantime.

Another thing that happens is that if I launch gnome-screenshot, it doesn’t hang but after I click Take Screenshot it takes ~20 seconds before actually taking it. In the meantime, I can’t launch other instances of gnome-screenshot.

At least one program (blender) won’t launch at all:

$  > ./blender --debug-all Switching to fully guarded memory allocator. 

then nothing for minutes.

The majority of other programs I use are unaffected by this.

Additional info:

  • I have a NVIDIA gpu, but this happens regardless of it being active or disabled through nvidia-prime
  • The problem doesn’t happen at every boot, but once I notice it, it is reproduced 100% of the time within that session
  • The laptop hasn’t been suspended

HTTP requests hang in otherwise working VLAN setup

I have 2 kvm virtualised servers. Each has a internet-facing ens3 and a ens6 interface for a VLAN bet ween the hosts. I’m running Ubuntu 18.04.

I have configured the interfaces via netplan.

network:   version: 2   renderer: networkd   ethernets:     ens3:       dhcp4: yes     ens6:       dhcp4: no       addresses: [10.0.0.10/24] 

The other machine has 10.0.0.20/24.

One machine runs multiple services and the other run runs Prometheus. I have setup node_exporter on both machines and listen on the privates networks ip address. I can ping from one machine to the other also connect via ssh between them. It seems connectivity works in general.

I can even curl the node_exporter from the second machine

curl http://10.0.0.10:9100 -v * Rebuilt URL to: http://10.0.0.10:9100/ *   Trying 10.0.0.10... * TCP_NODELAY set * Connected to 10.0.0.10 (10.0.0.10) port 9100 (#0) > GET / HTTP/1.1 > Host: 10.0.0.10:9100 > User-Agent: curl/7.58.0 > Accept: */* >  < HTTP/1.1 200 OK < Date: Mon, 31 Dec 2018 09:00:42 GMT < Content-Length: 150 < Content-Type: text/html; charset=utf-8 <  <html>             <head><title>Node Exporter</title></head>             <body>             <h1>Node Exporter</h1>             <p><a href="/metrics">Metrics</a></p>             </body> * Connection #0 to host 10.0.0.10 left intact 

The issue now comes when actually trying to pull the metrics:

curl http://10.0.0.10:9100/metrics -v *   Trying 10.0.0.10... * TCP_NODELAY set * Connected to 10.0.0.10 (10.0.0.10) port 9100 (#0) > GET /metrics HTTP/1.1 > Host: 10.0.0.10:9100 > User-Agent: curl/7.58.0 > Accept: */* >  ^C 

The connection simply hangs.

When doing the same curl command from the other machine itself, it works as expected. I also tried binding the node_exporter to 0.0.0.0. This also works, I can fetch the metrics through the servers public ip address.

I’m confused that a call to http://10.0.0.10:9100 works but not to http://10.0.0.10:9100/metrics. No errors or anything in my logs. Any idea what could be the reason for this?