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    <p>There seem to be some problems with the MySQL .NET library. A few days ago they fixed some of those issues with 6.2.2 related to releasing connections. But there is also a problem with SubSonic. I used the LINQ templates with MySQL to generate my classes. Whenever FirstOrDefault() or First() (the other similar functions probably have the same issue).</p> <p>For a query such as:</p> <pre><code>var db = new MyDb("CONNECTIONSTRING_NAME"); var userExt = (from pe in db.PhoneExtensions where pe.FirstName.ToLower() == firstName.ToLower() &amp;&amp; pe.LastName.ToLower() == lastName.ToLower() select pe.Extension).FirstOrDefault(); </code></pre> <p>This will cause the query to be executed and the reader will <strong>not</strong> be disposed.</p> <p>The problem is in Linq.Structure.DbQueryProvider in the Project of T method.</p> <pre><code>while (reader.Read()) { yield return fnProjector(reader); } reader.Dispose(); </code></pre> <p>The Dispose() never gets called when using FirstOrDefault() and other similar methods.</p> <p>A Simple fix:</p> <pre><code>try { while (reader.Read()) { yield return fnProjector(reader); } } finally { reader.Dispose(); } </code></pre> <p>Simple quick test showing the issue:</p> <pre><code>private class DbDataReader : System.IDisposable { #region IDisposable Members public void Dispose() { } #endregion } private class DbQueryProvider { private DbDataReader _reader; public bool IsReaderDisposed { get { return _reader == null; } } public DbQueryProvider() { _reader = new DbDataReader(); } public IEnumerable&lt;int&gt; Project(int numResults) { int i = 0; while (i &lt; numResults) { yield return i++; } _reader.Dispose(); _reader = null; } public IEnumerable&lt;int&gt; ProjectWithFinally(int numResults) { int i = 0; try { while (i &lt; numResults) { yield return i++; } } finally { _reader.Dispose(); _reader = null; } } } [Test] public void YieldReturn_Returns_TrueForIsReaderDisposed() { const int numResults = 1; var qp1 = new DbQueryProvider(); var q1 = qp1.Project(numResults); Assert.IsInstanceOf(typeof(int), q1.First()); var qp2 = new DbQueryProvider(); var q2 = qp2.Project(numResults); Assert.IsInstanceOf(typeof(int), q2.FirstOrDefault()); var qp3 = new DbQueryProvider(); var q3 = qp3.Project(numResults); Assert.IsInstanceOf(typeof(int), q3.Single()); var qp4 = new DbQueryProvider(); var q4 = qp4.Project(numResults); Assert.IsInstanceOf(typeof(int), q4.SingleOrDefault()); Assert.IsTrue(qp1.IsReaderDisposed); Assert.IsTrue(qp2.IsReaderDisposed); Assert.IsTrue(qp3.IsReaderDisposed); Assert.IsTrue(qp4.IsReaderDisposed); } [Test] public void YieldReturnFinally_Returns_TrueForIsReaderDisposed() { const int numResults = 1; var qp1 = new DbQueryProvider(); var q1 = qp1.ProjectWithFinally(numResults); Assert.IsInstanceOf(typeof(int), q1.First()); var qp2 = new DbQueryProvider(); var q2 = qp2.ProjectWithFinally(numResults); Assert.IsInstanceOf(typeof(int), q2.FirstOrDefault()); var qp3 = new DbQueryProvider(); var q3 = qp3.ProjectWithFinally(numResults); Assert.IsInstanceOf(typeof(int), q3.Single()); var qp4 = new DbQueryProvider(); var q4 = qp4.ProjectWithFinally(numResults); Assert.IsInstanceOf(typeof(int), q4.SingleOrDefault()); Assert.IsTrue(qp1.IsReaderDisposed); Assert.IsTrue(qp2.IsReaderDisposed); Assert.IsTrue(qp3.IsReaderDisposed); Assert.IsTrue(qp4.IsReaderDisposed); } </code></pre> <p>YieldReturnFinally_Returns_TrueForIsReaderDisposed passes but YieldReturn_Returns_TrueForIsReaderDisposed fails.</p> <p>I have tested this on the project I am working on which will soon be in production and this seems to work without any problems. Tested with a connection pool max size of 5 and had no connection pool issues (never ran out of connections on my dev machine when doing 1 query at a time). I also found some issues in Extensions.Database related to type changing and assignments.</p> <p>I forked the project on github, committed my changes and did a pull request, hopefully that gets to the right people.</p>
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