项目中使用微软RDLC生成工作票去打印，但是RDLC存在着严重的内存泄露问题。在生产高峰时期，工人将大量的工作票请求发送到服务器，随着工作票的生成内存就一点点的被吃掉。致使IT部门不得不为一个小小的工作票服务准备一台8G内存的服务器，并且定期的查看服务状态。在生产高峰时期每小时都要重启。

这个内存泄露问题自从VS2005以来就存在，微软声称在2008 SP1中已经修正，但是项目中使用的是2010的程序集版本且问题依然很严重。从微软官方的回复看由于RDLC使用VB进行表达式的计算，加载的VB相关的程序集由于某些原因不被Unload。我想微软在VS2008SP1中修正的应该是这个问题，当然我没有去考证，但是可以肯定的是在VS2010的RDLC中还是有内存泄露的代码存在。

网友还做过测试，如果不使用Expression就不会导致内存泄露，但是我并不想修改太多的程序，如果你的项目刚刚开始或并不复杂，这也是一个办法。参见原文：http://blog.darkthread.net/post-2012-01-12-rdlc-out-of-memory.aspx

于是着手从网上搜索如何查找内存泄露，推荐一个工具给大家。.Net Memory Profile http://memprofiler.com/. 这个工具可以分析出内存中哪些对象已经GC但是没有被成功的移除或移除的不够彻底。通过个这工具分析出LocalReport中的方法被事件或代理对象所引用无法GC。如下图

从上图可以看到LocalReport的身影，这张图中的所有对象全与RDLC有关。

在网上搜到一牛人用反射解决了ReportViewer的内存泄露问题。参见原贴：http://social.msdn.microsoft.com/Forums/en-US/vsreportcontrols/thread/d21f8b56-3123-4aff-bf84-9cce727bc2ce

于是我参考了这个做法结合.Net Memory Profiler的分析结果开始将LocalReport对象上的事件和代理去掉。虽然这个方法失败了还是把代码贴出来吧，如下：

using System;
using System.Reflection;
using System.Linq;
using System.Windows.Forms;
using Microsoft.Reporting.WinForms;
using Microsoft.Win32;
using System.Collections;
namespace TOG.ProductionOutput.Services
{
    public class LocalReportDisposer : IDisposable
    {
        // Fields
        private bool _CollectGarbageOnDispose = false;
        private LocalReport localReport;
        private bool disposedValue = false;
        private const string LOCALREPORT_DATASOURCES = "m_dataSources";
        private const string LOCALREPORT_PROCESSINGHOST = "m_processingHost";
        private const string PROCESSINGHOST_DATARETRIEVAL = "m_dataRetrieval";
        private const string DATARETRIEVAL_SUBREPORTDATACALLBACK = "m_subreportDataCallback";
        private const string SUBREPORTDATACALLBACK_TARGET = "_target";
        private const string PROCESSINGHOST_EXECUTIONSESSION = "m_executionSession";
        private const string EXECUTIONSESSION_COMPILEDREPORT = "__compiledReport";
        private const string EXECUTIONSESSION_REPORTSNAPSHOT = "__ReportSnapshot";
        private const string DATASOURCES_ONCHANGE = "OnChange";
        // Methods
        public LocalReportDisposer(LocalReport localReport)
        {
            if (localReport == null)
            {
                throw new ArgumentNullException("ReportViewer cannot be null.");
            }
            this.localReport = localReport;
        }
        public void Dispose()
        {
            this.Dispose(true);
            GC.SuppressFinalize(this);
        }
        protected virtual void Dispose(bool disposing)
        {
            if (!this.disposedValue && disposing)
            {
                //this.TearDownLocalReport();
                this.localReport.Dispose();
                if (this._CollectGarbageOnDispose)
                {
                    GC.Collect();
                    GC.WaitForPendingFinalizers();
                    GC.Collect();
                }
            }
            this.disposedValue = true;
        }
        private void TearDownLocalReport()
        {
            Type t = this.localReport.GetType();
            //localReport.m_dataSources
            FieldInfo fi = t.GetField(LOCALREPORT_DATASOURCES, BindingFlags.NonPublic | BindingFlags.Instance);
            object dataSources = fi.GetValue(this.localReport);
            //remove event from localReport.m_dataSources.Change
            ReflectUtil.RemoveEventHandlersFrom(
                delegate(Delegate subject) { return subject.Method.Name == DATASOURCES_ONCHANGE; },
                dataSources);
            //localReport.m_processingHost
            fi = t.GetField(LOCALREPORT_PROCESSINGHOST, BindingFlags.NonPublic | BindingFlags.Instance);
            object processingHost = fi.GetValue(this.localReport);
            //localReport.m_processingHost.dataretrieval
            t = processingHost.GetType().BaseType;
            fi = t.GetField(PROCESSINGHOST_DATARETRIEVAL, BindingFlags.NonPublic | BindingFlags.Instance);
            object dataRetrieval = fi.GetValue(processingHost);
            //localReport.m_processingHost.m_dataRetrieval.m_subreportDataCallback
            t = dataRetrieval.GetType();
            fi = t.GetField(DATARETRIEVAL_SUBREPORTDATACALLBACK, BindingFlags.NonPublic | BindingFlags.Instance);
            object subReportDataCallBack = fi.GetValue(dataRetrieval);
            //localReport.m_processingHost.m_dataRetrieval.m_subreportDataCallback._target
            t = subReportDataCallBack.GetType().BaseType.BaseType;
            fi = t.GetField(SUBREPORTDATACALLBACK_TARGET, BindingFlags.NonPublic | BindingFlags.Instance);
            fi.SetValue(subReportDataCallBack, null);
            t = processingHost.GetType().BaseType;
            fi = t.GetField(PROCESSINGHOST_EXECUTIONSESSION, BindingFlags.NonPublic | BindingFlags.Instance);
            object executionSession = fi.GetValue(processingHost);
            t = executionSession.GetType();
            fi = t.GetField(EXECUTIONSESSION_COMPILEDREPORT, BindingFlags.NonPublic | BindingFlags.Instance);
            IDisposable report = fi.GetValue(executionSession) as IDisposable;
            if (report != null) report.Dispose();
            fi = t.GetField(EXECUTIONSESSION_REPORTSNAPSHOT, BindingFlags.NonPublic | BindingFlags.Instance);
            report = fi.GetValue(executionSession) as IDisposable;
            if (report != null) report.Dispose();
        }
        // Properties
        public bool CollectGarbageOnDispose
        {
            get
            {
                return this._CollectGarbageOnDispose;
            }
            set
            {
                this._CollectGarbageOnDispose = value;
            }
        }
    }
}

using System;using System.Reflection;using System.Linq;using System.Windows.Forms;  using Microsoft.Reporting.WinForms;  using Microsoft.Win32;using System.Collections;namespace TOG.ProductionOutput.Services{publicclass LocalReportDisposer : IDisposable   {// Fields  privatebool _CollectGarbageOnDispose = false;private LocalReport localReport;privatebool disposedValue = false;privateconststring LOCALREPORT_DATASOURCES = "m_dataSources";privateconststring LOCALREPORT_PROCESSINGHOST = "m_processingHost";privateconststring PROCESSINGHOST_DATARETRIEVAL = "m_dataRetrieval";privateconststring DATARETRIEVAL_SUBREPORTDATACALLBACK = "m_subreportDataCallback";privateconststring SUBREPORTDATACALLBACK_TARGET = "_target";privateconststring PROCESSINGHOST_EXECUTIONSESSION = "m_executionSession";privateconststring EXECUTIONSESSION_COMPILEDREPORT = "__compiledReport";privateconststring EXECUTIONSESSION_REPORTSNAPSHOT = "__ReportSnapshot";privateconststring DATASOURCES_ONCHANGE = "OnChange";// Methods  public LocalReportDisposer(LocalReport localReport)     {if (localReport == null)       {thrownew ArgumentNullException("ReportViewer cannot be null.");       }this.localReport = localReport;     }publicvoid Dispose()     {this.Dispose(true);       GC.SuppressFinalize(this);     }protectedvirtualvoid Dispose(bool disposing)     {if (!this.disposedValue && disposing)       {//this.TearDownLocalReport();this.localReport.Dispose();if (this._CollectGarbageOnDispose)         {           GC.Collect();           GC.WaitForPendingFinalizers();           GC.Collect();         }       }this.disposedValue = true;     }privatevoid TearDownLocalReport()     {       Type t = this.localReport.GetType();//localReport.m_dataSourcesFieldInfo fi = t.GetField(LOCALREPORT_DATASOURCES, BindingFlags.NonPublic | BindingFlags.Instance);object dataSources = fi.GetValue(this.localReport);//remove event from localReport.m_dataSources.ChangeReflectUtil.RemoveEventHandlersFrom(delegate(Delegate subject) { return subject.Method.Name == DATASOURCES_ONCHANGE; },         dataSources);//localReport.m_processingHostfi = t.GetField(LOCALREPORT_PROCESSINGHOST, BindingFlags.NonPublic | BindingFlags.Instance);object processingHost = fi.GetValue(this.localReport);//localReport.m_processingHost.dataretrievalt = processingHost.GetType().BaseType;       fi = t.GetField(PROCESSINGHOST_DATARETRIEVAL, BindingFlags.NonPublic | BindingFlags.Instance);object dataRetrieval = fi.GetValue(processingHost);//localReport.m_processingHost.m_dataRetrieval.m_subreportDataCallbackt = dataRetrieval.GetType();       fi = t.GetField(DATARETRIEVAL_SUBREPORTDATACALLBACK, BindingFlags.NonPublic | BindingFlags.Instance);object subReportDataCallBack = fi.GetValue(dataRetrieval);//localReport.m_processingHost.m_dataRetrieval.m_subreportDataCallback._targett = subReportDataCallBack.GetType().BaseType.BaseType;       fi = t.GetField(SUBREPORTDATACALLBACK_TARGET, BindingFlags.NonPublic | BindingFlags.Instance);       fi.SetValue(subReportDataCallBack, null);       t = processingHost.GetType().BaseType;       fi = t.GetField(PROCESSINGHOST_EXECUTIONSESSION, BindingFlags.NonPublic | BindingFlags.Instance);object executionSession = fi.GetValue(processingHost);       t = executionSession.GetType();       fi = t.GetField(EXECUTIONSESSION_COMPILEDREPORT, BindingFlags.NonPublic | BindingFlags.Instance);       IDisposable report = fi.GetValue(executionSession) as IDisposable;if (report != null) report.Dispose();       fi = t.GetField(EXECUTIONSESSION_REPORTSNAPSHOT, BindingFlags.NonPublic | BindingFlags.Instance);       report = fi.GetValue(executionSession) as IDisposable;if (report != null) report.Dispose();     }// Properties  publicbool CollectGarbageOnDispose     {get{returnthis._CollectGarbageOnDispose;       }set{this._CollectGarbageOnDispose = value;       }     }   }}

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Reflection;
namespace TOG.ProductionOutput.Services
{
    public sealed class ReflectUtil
    {
        private static BindingFlags PrivatePublicStaticInstance
          = BindingFlags.NonPublic | BindingFlags.Public |
            BindingFlags.Instance | BindingFlags.Static;
        public delegate bool MatchesOnDelegate(Delegate subject);
        public static void RemoveEventHandlersFrom(
          MatchesOnDelegate matchesOnDelegate, params object[] objectsWithEvents)
        {
            foreach (object owningObject in objectsWithEvents)
            {
                foreach (DelegateInfo eventFromOwningObject in GetDelegates(owningObject))
                {
                    foreach (Delegate subscriber in eventFromOwningObject.GetInvocationList())
                    {
                        if (matchesOnDelegate(subscriber))
                        {
                            EventInfo theEvent = eventFromOwningObject.GetEventInfo();
                            if(theEvent != null)
                                RemoveSubscriberEvenIfItsPrivate(theEvent, owningObject, subscriber);
                        }
                    }
                }
            }
        }
        // You can use eventInfo.RemoveEventHandler(owningObject, subscriber)
        // unless it's a private delegate
        private static void RemoveSubscriberEvenIfItsPrivate(
          EventInfo eventInfo, object owningObject, Delegate subscriber)
        {
            MethodInfo privateRemoveMethod = eventInfo.GetRemoveMethod(true);
            privateRemoveMethod.Invoke(owningObject,
                                       PrivatePublicStaticInstance, null,
                                       new object[] { subscriber }, CultureInfo.CurrentCulture);
        }
        private static DelegateInfo[] GetDelegates(object owningObject)
        {
            List delegates = new List();
            FieldInfo[] allPotentialEvents = owningObject.GetType()
              .GetFields(PrivatePublicStaticInstance);
            foreach (FieldInfo privateFieldInfo in allPotentialEvents)
            {
                Delegate eventFromOwningObject = privateFieldInfo.GetValue(owningObject)
                  as Delegate;
                if (eventFromOwningObject != null)
                {
                    delegates.Add(new DelegateInfo(eventFromOwningObject, privateFieldInfo,
                      owningObject));
                }
            }
            return delegates.ToArray();
        }
        private class DelegateInfo
        {
            private readonly Delegate delegateInformation;
            public Delegate DelegateInformation
            {
                get { return delegateInformation; }
            }
            private readonly FieldInfo fieldInfo;
            private readonly object owningObject;
            public DelegateInfo(Delegate delegateInformation, FieldInfo fieldInfo,
              object owningObject)
            {
                this.delegateInformation = delegateInformation;
                this.fieldInfo = fieldInfo;
                this.owningObject = owningObject;
            }
            public Delegate[] GetInvocationList()
            {
                return delegateInformation.GetInvocationList();
            }
            public EventInfo GetEventInfo()
            {
                return owningObject.GetType().GetEvent(fieldInfo.Name,
                  PrivatePublicStaticInstance);
            }
        }
    }
}

using System;using System.Collections.Generic;using System.Globalization;using System.Reflection;namespace TOG.ProductionOutput.Services{publicsealedclass ReflectUtil   {privatestatic BindingFlags PrivatePublicStaticInstance      = BindingFlags.NonPublic | BindingFlags.Public |       BindingFlags.Instance | BindingFlags.Static;publicdelegatebool MatchesOnDelegate(Delegate subject);publicstaticvoid RemoveEventHandlersFrom(      MatchesOnDelegate matchesOnDelegate, paramsobject[] objectsWithEvents)     {foreach (object owningObject in objectsWithEvents)       {foreach (DelegateInfo eventFromOwningObject in GetDelegates(owningObject))         {foreach (Delegate subscriber in eventFromOwningObject.GetInvocationList())           {if (matchesOnDelegate(subscriber))             {               EventInfo theEvent = eventFromOwningObject.GetEventInfo();if(theEvent != null)                 RemoveSubscriberEvenIfItsPrivate(theEvent, owningObject, subscriber);             }           }         }       }     }// You can use eventInfo.RemoveEventHandler(owningObject, subscriber) // unless it's a private delegateprivatestaticvoid RemoveSubscriberEvenIfItsPrivate(      EventInfo eventInfo, object owningObject, Delegate subscriber)     {       MethodInfo privateRemoveMethod = eventInfo.GetRemoveMethod(true);       privateRemoveMethod.Invoke(owningObject,                    PrivatePublicStaticInstance, null,                    newobject[] { subscriber }, CultureInfo.CurrentCulture);     }privatestatic DelegateInfo[] GetDelegates(object owningObject)     {       List delegates = new List();       FieldInfo[] allPotentialEvents = owningObject.GetType()        .GetFields(PrivatePublicStaticInstance);foreach (FieldInfo privateFieldInfo in allPotentialEvents)       {         Delegate eventFromOwningObject = privateFieldInfo.GetValue(owningObject)          as Delegate;if (eventFromOwningObject != null)         {           delegates.Add(new DelegateInfo(eventFromOwningObject, privateFieldInfo,            owningObject));         }       }return delegates.ToArray();     }privateclass DelegateInfo     {privatereadonly Delegate delegateInformation;public Delegate DelegateInformation       {get { return delegateInformation; }       } privatereadonly FieldInfo fieldInfo;privatereadonlyobject owningObject;public DelegateInfo(Delegate delegateInformation, FieldInfo fieldInfo,        object owningObject)       {this.delegateInformation = delegateInformation;this.fieldInfo = fieldInfo;this.owningObject = owningObject;       }public Delegate[] GetInvocationList()       {return delegateInformation.GetInvocationList();       }public EventInfo GetEventInfo()       {return owningObject.GetType().GetEvent(fieldInfo.Name,          PrivatePublicStaticInstance);       }     }   }}

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