title: LINQ To SQL says Invalid attempt to call Read when reader is closed
body: <p>I have a server and a client. Server is a web application hosting WCF service. Server uses Linq2SQL DataContext via static singleton which is being initialized upon first access and is never disposed (in my code). Client makes calls to the server via WCF, queries some information from database, makes updates. Everything works fine until several clients access server concurrently. When that happens server throws different exceptions:</p>
  <blockquote>
  <p>Invalid attempt to call Read when reader is closed.</p>
  <p>There is already an open DataReader associated with this Command which must be closed first.</p>
  </blockquote>
  <p>As far as I understand the problem is that I'm using static singleton, and it gets somehow shared between client connections, but my primary objective was to minimize amount of connections to database.</p>
  <p>Why does this happen?</p>