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POMemory leak with non nhibernate entities
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  1. POMemory leak with non nhibernate entities
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    copied!<p>I'm having a strange situation of a memory leak in NHibernate and ActiveRecord. I'm designed a system to load specific columns of entities in order to convert it to a flat order and transfer them over the network. It's hosted in IIS and serves as central point for several Point Of Sale devices.</p> <p>This system worked just fine for very large amount of entities, up to millions at a time. </p> <p>It basically works by determining which columns are required from the entity metadata, extracting it to a projection and executing a query with a result transformer.</p> <p>I'm not sure what changed, but I've encountered a situation where I'm seeing a memory leak of the transformed results, where the profiler tells me that the entities are being held in some List in the class Loader in the method DoQuery. I can't find anything in that method that would cause them to be held. </p> <p>Here is the function I'm using to get the row values, and it is also used for loading other normal NHibernate entities that I have:</p> <pre><code> public static IList GetResultsForCriteria(DetachedCriteria crit, int? maxResults,TransactionLockModeEnum transactionLockMode) { ISessionFactoryHolder holder = ActiveRecordMediator.GetSessionFactoryHolder(); ISession session = holder.CreateSession(typeof(object)); session.FlushMode = FlushMode.Never; ITransaction transaction = null; if (transactionLockMode == TransactionLockModeEnum.NonLocking) { transaction = session.BeginTransaction(IsolationLevel.ReadUncommitted); } ICriteria executableCriteria = crit.GetExecutableCriteria(session); if (maxResults.HasValue) { executableCriteria.SetMaxResults(maxResults.Value); } IList results; try { if (session.Connection.State == ConnectionState.Closed) { session.Connection.Open(); } results = executableCriteria.List(); if (transaction != null) { transaction.Commit(); } ConnectionMonitor.AddConnection(session.Connection); } finally { holder.ReleaseSession(session); } return results; } </code></pre> <p>Here is the transformer that I'm using to convert from raw values to a dictionary with property names and values:</p> <pre><code>class EntityRetrieverResultTransform : IResultTransformer { public object TransformTuple(object[] tuple, string[] aliases) { EntityFields fields = new EntityFields(); for (int i = 0; i &lt; tuple.Length; i++) { string aliasName = aliases[i].Replace("[","").Replace("]",""); fields.Add(aliasName,tuple[i]); } return fields; } public IList TransformList(IList collection) { return collection; } } </code></pre> <p>the class EntityFields is a simple class:</p> <pre><code>public class EntityFields : Dictionary&lt;string,object&gt; { } </code></pre> <p>Here is a root graph from the profiler for a specific instance of the class EntityFields:</p> <p><img src="https://i.stack.imgur.com/U9ukC.png" alt="Root graph"> <a href="https://i.stack.imgur.com/U9ukC.png" rel="nofollow noreferrer">http://i.stack.imgur.com/U9ukC.png</a></p> <p>As you can see between DoQuery and List, there's no field name.</p> <p>At first I thought that the problem was with the result transformer, but even after taking that off, I still saw a memory leak of the raw values as string[].</p> <p>What am I doing wrong? Why are the EntityFields instances being held in the session?</p>
 

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