title: npm hangs on postinstall / unlock
body: <p>I have a Linux server that runs some virtual Machines using KVM. Host machine is a Debian derivate with kernel 2.6.32-32(-pve).</p>
  
  <p>In roughly 75% of the times I run <code>npm install</code>, it hangs while installing modules. I ran it in silly debug level and it always hangs at the line</p>
  
  <p><code>npm info postinstall [module name]</code> (older npm versions)</p>
  
  <p>or</p>
  
  <p><code>npm verb unlock done using [...]</code> (newer npm versions)</p>
  
  <p>forever.</p>
  
  <p>It happens in every project on the host machine and on the virtualized systems for every node and every npm version I have tested (a lot, including the newest ones (2.7.x atm)).</p>
  
  <p>It also is not deterministic. Sometimes it works, sometimes not and most of the times it hangs on a different module.</p>
  
  <p>On my dev machine (which is in the same network, running OS X 10.10) it works fine.</p>
  
  <p>I am not behind any kind of proxy.</p>
  
  <p>What could possibly be wrong here?</p>
  
  <p><strong>EDIT</strong>: For the time being I solved this problem by checking in all my dependencies as gzipped files using <a href="https://github.com/JamieMason/shrinkpack" rel="noreferrer">https://github.com/JamieMason/shrinkpack</a></p>