Microsoft.Web.Administration内存泄漏

Question

有一个Windows服务，其中包括监视IIS应用程序池。如果任何池已配置应用程序且未运行，则启动它（池）。这已经有一段时间了。最近发现该服务泄漏了内存。查看内存转储的罪魁祸首是用于检查应用程序池的Microsoft.Web.Administration。唯一可以使用的对象是ServerManager，我在使用块中有这个对象。已找到有关此泄漏的其他报告但尚无解决方案。 （参见http://msdn.microsoft.com/en-us/library/microsoft.web.administration.servermanager(v=vs.90).aspx#CommunityContent）中的用户评论

当转储Microsoft.Web.Administration.ServerManager（此转储中的481）的所有根时，我只看到其中一个根。假设这是当前的迭代。

不确定为什么无法收集这些Web.Administration对象，即使它们似乎没有根源（？）。关于如何堵塞这种泄漏的任何想法？

我将代码移动到控制台应用程序并在那里重现泄漏。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using Microsoft.Web.Administration;

namespace Web.Administration.LeakExample
{
    public static class ServerManagerExtensions
    {
        /// <summary>
        /// Returns the application counts for application pools under the specified ServerManager.
        /// Application pools without applications will not be returned.
        /// </summary>
        /// <param name="manager"></param>
        /// <returns></returns>
        public static Dictionary<string, uint> GetPoolApplicationCounts(this ServerManager manager)
        {
            if (manager == null)
            {
                throw new ArgumentNullException();
            }

            var appCounts = new Dictionary<string, uint>(manager.ApplicationPools.Count);
            foreach (var app in manager.Sites.SelectMany(site => site.Applications))
            {
                if (!appCounts.ContainsKey(app.ApplicationPoolName))
                {
                    appCounts.Add(app.ApplicationPoolName, 1);
                }
                else
                {
                    appCounts[app.ApplicationPoolName]++;
                }
            }

            return appCounts;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            while (!Console.KeyAvailable)
            {
                Console.WriteLine("Checking App Pools...");

                using (var manager = new ServerManager())
                {
                    var appCounts = manager.GetPoolApplicationCounts();

                    var appPools = manager.ApplicationPools.Where(pool => appCounts.ContainsKey(pool.Name));

                    foreach (
                        var pool in
                            appPools.Where(
                                pool => (pool.State != ObjectState.Started) && (pool.State != ObjectState.Starting)))
                    {
                        var state = pool.Start();

                        if ((state == ObjectState.Started) || (state == ObjectState.Starting))
                        {
                            Console.WriteLine("Started app pool \"{0}\"", pool.Name);
                        }
                        else
                        {
                            Console.WriteLine("Failed to start app pool \"{0}\". state:{1}", pool.Name, state);
                        }
                    }
                }

                Console.WriteLine("Sleeping...");
                Thread.Sleep(1000);
            }
        }
    }
}

WinDbg会话：

> !dumpheap -stat

606b778c      479         5748 System.Runtime.Remoting.Activation.ConstructionLevelActivator
00472088      480         5760 System.Collections.Generic.Dictionary`2+ValueCollection[[System.String, mscorlib],[Microsoft.Web.Administration.Interop.IAppHostElement, Microsoft.Web.Administration]]
00471d5c      480         5760 System.Collections.Generic.SortedList`2+ValueList[[System.String, mscorlib],[Microsoft.Web.Administration.Configuration, Microsoft.Web.Administration]]
00194568      481         5772 Web.Administration.LeakExample.Program+<>c__DisplayClass3
00198438      480         7680 Microsoft.Web.Administration.Interop.AppHostWritableAdminManager
0047199c      481         7696 System.Linq.Enumerable+<>c__DisplayClassf`1[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
606cc200      958        11496 System.Char
00471e2c      479        11496 System.Collections.Generic.SortedList`2+SortedListValueEnumerator[[System.String, mscorlib],[Microsoft.Web.Administration.Configuration, Microsoft.Web.Administration]]
0047090c      479        11496 System.Collections.Generic.List`1+Enumerator[[Microsoft.Web.Administration.Site, Microsoft.Web.Administration]]
004706f0      958        11496 Microsoft.Web.Administration.ConfigurationElementCollectionBase`1+<>c__DisplayClass4[[Microsoft.Web.Administration.Site, Microsoft.Web.Administration]]
00471aec      480        11520 System.Collections.Generic.List`1+Enumerator[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
0047041c      480        11520 System.Collections.Generic.List`1[[Microsoft.Web.Administration.Site, Microsoft.Web.Administration]]
00196d58      480        11520 System.Collections.Generic.List`1[[Microsoft.Web.Administration.Configuration, Microsoft.Web.Administration]]
004715cc      481        11544 System.Collections.Generic.List`1[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
0047103c     1437        17244 Microsoft.Web.Administration.ConfigurationElementCollectionBase`1+<>c__DisplayClass4[[Microsoft.Web.Administration.Application, Microsoft.Web.Administration]]
606ccfc8     1438        17256 System.Int32
00196a58      480        19200 System.Collections.Generic.SortedList`2[[System.String, mscorlib],[Microsoft.Web.Administration.Configuration, Microsoft.Web.Administration]]
0019660c      480        21120 Microsoft.Web.Administration.ConfigurationManager
00471130      958        22992 System.Collections.Generic.List`1+Enumerator[[Microsoft.Web.Administration.Application, Microsoft.Web.Administration]]
00470d68      960        23040 System.Collections.Generic.List`1[[Microsoft.Web.Administration.Application, Microsoft.Web.Administration]]
00198558      480        23040 System.Collections.Generic.Dictionary`2[[System.String, mscorlib],[Microsoft.Web.Administration.Interop.IAppHostElement, Microsoft.Web.Administration]]
00196a08      481        23088 Microsoft.Web.Administration.Configuration
00183170      481        23088 System.Collections.Generic.Dictionary`2[[System.String, mscorlib],[System.UInt32, mscorlib]]
606b7574      479        24908 System.Runtime.Remoting.Messaging.ConstructorCallMessage
00199e7c      479        24908 System.Linq.Enumerable+<SelectManyIterator>d__14`2[[Microsoft.Web.Administration.Site, Microsoft.Web.Administration],[Microsoft.Web.Administration.Application, Microsoft.Web.Administration]]
00199384      480        28800 System.Collections.Generic.Dictionary`2+Entry[[System.String, mscorlib],[Microsoft.Web.Administration.Interop.IAppHostElement, Microsoft.Web.Administration]][]
00470874      958        30656 System.Predicate`1[[Microsoft.Web.Administration.Site, Microsoft.Web.Administration]]
004718a8      962        30784 System.Linq.Enumerable+WhereEnumerableIterator`1[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
001944d8      481        30784 Microsoft.Web.Administration.ServerManager
00195178      963        30816 System.Func`2[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration],[System.Boolean, mscorlib]]
606ccf90      968        31268 System.Int32[]
00197a50      480        32640 Microsoft.Web.Administration.SiteCollection
00194da0      481        32708 Microsoft.Web.Administration.ApplicationPoolCollection
004719f8     2874        34488 Microsoft.Web.Administration.ConfigurationElementCollectionBase`1+<>c__DisplayClass4[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
0019810c      960        42240 Microsoft.Web.Administration.ConfigurationSection
00471098     1437        45984 System.Predicate`1[[Microsoft.Web.Administration.Application, Microsoft.Web.Administration]]
606cc1c8      961        46638 System.Char[]
001838d0      481        59644 System.Collections.Generic.Dictionary`2+Entry[[System.String, mscorlib],[System.UInt32, mscorlib]][]
606bedd0     5269        63228 System.UInt32
00470a7c      960        69120 Microsoft.Web.Administration.ApplicationCollection
00197c60      960        76800 Microsoft.Web.Administration.Site
00197ea8     1440        86400 Microsoft.Web.Administration.Application
00471a54     2874        91968 System.Predicate`1[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
6067c684     4832       141272 System.Object[]
00195024     2886       196248 Microsoft.Web.Administration.ApplicationPool
606c7b20    16323       261168 System.__ComObject

>.foreach (obj {!dumpheap -mt 001944d8 -short}){!gcroot -all obj}

    002ef124 003f0359 Web.Administration.LeakExample.Program.Main(System.String[]) [c:\Users\Chuck\Documents\Visual Studio 2012\Projects\Web.Administration.LeakExample\Web.Administration.LeakExample\Program.cs @ 74]
        ebp+70: 002ef148
            ->  02773270 System.Linq.Enumerable+WhereEnumerableIterator`1[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
            ->  02772948 Microsoft.Web.Administration.ApplicationPoolCollection
            ->  02772060 Microsoft.Web.Administration.ServerManager

    002ef124 003f0359 Web.Administration.LeakExample.Program.Main(System.String[]) [c:\Users\Chuck\Documents\Visual Studio 2012\Projects\Web.Administration.LeakExample\Web.Administration.LeakExample\Program.cs @ 74]
        ebp+68: 002ef150
            ->  02773270 System.Linq.Enumerable+WhereEnumerableIterator`1[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
            ->  02772948 Microsoft.Web.Administration.ApplicationPoolCollection
            ->  02772060 Microsoft.Web.Administration.ServerManager

    002ef124 003f0359 Web.Administration.LeakExample.Program.Main(System.String[]) [c:\Users\Chuck\Documents\Visual Studio 2012\Projects\Web.Administration.LeakExample\Web.Administration.LeakExample\Program.cs @ 74]
        ebp+78: 002ef140
            ->  027732c0 System.Linq.Enumerable+WhereEnumerableIterator`1[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
            ->  02772948 Microsoft.Web.Administration.ApplicationPoolCollection
            ->  02772060 Microsoft.Web.Administration.ServerManager

    002ef124 003f0359 Web.Administration.LeakExample.Program.Main(System.String[]) [c:\Users\Chuck\Documents\Visual Studio 2012\Projects\Web.Administration.LeakExample\Web.Administration.LeakExample\Program.cs @ 74]
        ebp+6c: 002ef14c
            ->  02773270 System.Linq.Enumerable+WhereEnumerableIterator`1[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
            ->  02772948 Microsoft.Web.Administration.ApplicationPoolCollection
            ->  02772060 Microsoft.Web.Administration.ServerManager

    002ef124 003f0359 Web.Administration.LeakExample.Program.Main(System.String[]) [c:\Users\Chuck\Documents\Visual Studio 2012\Projects\Web.Administration.LeakExample\Web.Administration.LeakExample\Program.cs @ 74]
        ebp+74: 002ef144
            ->  027732c0 System.Linq.Enumerable+WhereEnumerableIterator`1[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
            ->  02772948 Microsoft.Web.Administration.ApplicationPoolCollection
            ->  02772060 Microsoft.Web.Administration.ServerManager

    002ef124 003f0359 Web.Administration.LeakExample.Program.Main(System.String[]) [c:\Users\Chuck\Documents\Visual Studio 2012\Projects\Web.Administration.LeakExample\Web.Administration.LeakExample\Program.cs @ 74]
        ebp+60: 002ef158
            ->  02772948 Microsoft.Web.Administration.ApplicationPoolCollection
            ->  02772060 Microsoft.Web.Administration.ServerManager

    002ef124 003f0359 Web.Administration.LeakExample.Program.Main(System.String[]) [c:\Users\Chuck\Documents\Visual Studio 2012\Projects\Web.Administration.LeakExample\Web.Administration.LeakExample\Program.cs @ 74]
        ebp+3c: 002ef17c
            ->  02772060 Microsoft.Web.Administration.ServerManager

    002ef124 003f0359 Web.Administration.LeakExample.Program.Main(System.String[]) [c:\Users\Chuck\Documents\Visual Studio 2012\Projects\Web.Administration.LeakExample\Web.Administration.LeakExample\Program.cs @ 74]
        ebp+4c: 002ef16c
            ->  027732c0 System.Linq.Enumerable+WhereEnumerableIterator`1[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
            ->  02772948 Microsoft.Web.Administration.ApplicationPoolCollection
            ->  02772060 Microsoft.Web.Administration.ServerManager

    002ef124 003f0359 Web.Administration.LeakExample.Program.Main(System.String[]) [c:\Users\Chuck\Documents\Visual Studio 2012\Projects\Web.Administration.LeakExample\Web.Administration.LeakExample\Program.cs @ 74]
        ebp+40: 002ef178
            ->  02773270 System.Linq.Enumerable+WhereEnumerableIterator`1[[Microsoft.Web.Administration.ApplicationPool, Microsoft.Web.Administration]]
            ->  02772948 Microsoft.Web.Administration.ApplicationPoolCollection
            ->  02772060 Microsoft.Web.Administration.ServerManager

    002ef124 003f0359 Web.Administration.LeakExample.Program.Main(System.String[]) [c:\Users\Chuck\Documents\Visual Studio 2012\Projects\Web.Administration.LeakExample\Web.Administration.LeakExample\Program.cs @ 74]
        ebp+50: 002ef168
            ->  02772060 Microsoft.Web.Administration.ServerManager

Found 10 roots.

Answer 1

当我第一次阅读这个问题时，我发现的第一件事就是使用Windows Activation Service (WAS)可以完全避免这个问题。

我首次浏览您发布的代码，让我觉得您的问题可能与访问/修改foreach循环创建的各种闭包有关。

尝试这些小型重构，看看是否有任何/所有能够减少或消除问题或失败，提供更多关于根本原因的信息：

1. 通过立即调用.ToList()
来避免延迟执行您的LINQ查询
2. 不是重复使用ServerManager对象，而是在循环的每次迭代中创建一个新对象

3. 由于您只使用ApplicationPool.Name，因此请重构：

   foreach (var app in manager.Sites.SelectMany(site => site.Applications))

到此：

foreach (var app in manager.Sites.SelectMany(site => site.Applications, 
   (s, a) => a.Name)
    .ToList())

我的假设是这就是发生的事情：

• 在ServerManager声明
中创建了using的新实例
• 在该对象引用上调用静态扩展方法，该方法在内部使用ApplicationPools
• ApplicationPools会立即再次用于构建IQueryable，它会立即使用（但不完全执行 - foreach语句在内部使用yield return）并进行过滤。
• 调用.Start()对象引用所引用的ApplicationPool的{​​{1}}更改（变异）状态
• 其余部分不相关，所以循环回到开头。它仍然使用相同的ServerManager。由于该引用具有变异状态（因为调用ServerManager），它可能被GC标记并且从未收集 - 在后续迭代的结果中永远不会返回该应用程序池，并且可能导致引用的孤立在记忆中。

这只是一个假设，请记住！

Answer 2

我现在相信这不是真正的泄漏。我尝试了ToList（）以及Josh建议的所有内容。这不会影响内存使用。

我在循环中添加了GC.Collect（）（仅用于测试目的），并消除了“泄漏”。我通过内存转储验证了这一点，我发现堆上没有Web.Application对象。这恰好与我在之前的转储中看到的所有Web.Application对象中的所有对象实际上都是根的一致。其他人没有扎根，等待收集。

我被.NET垃圾收集器的非确定性特性绊倒了。对不起噪音。

Answer 3

我在这里找到了解决方案：www.tomanderson.me。

建议使用

using (ServerManager sm = ServerManager.OpenRemote("localhost"))
{ /*..*/ }

对我有用。