title: Ghostscript.net multiThreaded issue
body: <p>I have a Sharepoint application that uses the Ghostscript.net wrapper to rasterize pdf documents to png.  Right now I am using the example from their <a href="https://ghostscriptnet.codeplex.com/SourceControl/latest#Ghostscript.NET/Ghostscript.NET.Samples/Samples/RasterizerSample.cs" rel="nofollow noreferrer">site</a>. But the issue I have is when I try to convert to pdfs at the same time.  Using this code works only one at a time. But I get the error &quot;An error occured when call to 'gsapi_new_instance' is made: -100&quot; when I attempt to convert 2 pdf's simultaneously.</p>
  <pre><code>               using (MemoryStream pdfStream = new MemoryStream(pdfbyte))
              using (GhostscriptRasterizer rasterizer = new GhostscriptRasterizer())
              {
  
                  rasterizer.Open(pdfStream, version, false);
                  for (int i = 1; i &lt;= rasterizer.PageCount; i++)
                  {
  
                      using (MemoryStream ms = new MemoryStream())
                      {
                          DrawImage img = rasterizer.GetPage(dpi, dpi, i);
                          img.Save(ms, ImageFormat.Png);
                          ms.Close();
                          output = &quot;data:image/png;base64,&quot; + Convert.ToBase64String((byte[])ms.ToArray());
  
                      }
  
                  }
  
                  rasterizer.Close();
  </code></pre>
  <p>Otherwise if I use <code>rasterizer.Open(pdfStream, version, true);</code> I the error &quot;Arithmetic operation resulted in an overflow&quot;</p>
  <p>Should I be using a GhostscriptProcessor or Viewer instance instead?  Does anyone have a good example of this code?</p>