Microsoft.Web.Administration 内存泄漏

2024-05-27

拥有一个 Windows 服务,除其他外,还可以监视 IIS 应用程序池。如果任何池已配置应用程序但未运行,则该池(池)将启动。这已经运行良好一段时间了。最近发现该服务存在内存泄漏。查看内存转储,罪魁祸首是用于检查应用程序池的 Microsoft.Web.Administration。唯一可一次性的对象是 ServerManager,我将其放在 using 块中。已找到有关此泄漏的其他报告,但尚未解决。 (参见用户评论http://msdn.microsoft.com/en-us/library/microsoft.web.administration.servermanager(v=vs.90).aspx#CommunityContent http://msdn.microsoft.com/en-us/library/microsoft.web.administration.servermanager(v=vs.90).aspx#CommunityContent)

当转储 Microsoft.Web.Administration.ServerManager 的所有根(此转储中的 481)时,我只看到其中之一的根。假设这是当前迭代。

不知道为什么这些 Web.Administration 对象无法被收集,即使它们似乎没有被 root(?)。关于如何堵住这个漏洞有什么想法吗?

我将代码移至控制台应用程序并在那里重现了泄漏。

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.

当我第一次读到这个问题时,我首先想到的是,通过使用Windows 激活服务 (WAS) http://msdn.microsoft.com/en-us/library/ms789006.aspx.

我第一次浏览您发布的代码给我的感觉是您的问题可能与访问/修改由foreach loops.

尝试这些小的重构,看看是否有任何/全部能够减少或消除问题,如果失败,请提供有关根本原因的更多信息:

  1. 通过调用避免延迟执行 LINQ 查询.ToList()立即地
  2. 而不是重新使用ServerManager对象,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,重构这个:

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

to this:

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

我的假设是,这就是正在发生的事情:

  • 新实例ServerManager创建于using陈述
  • 在该对象引用上调用静态扩展方法,该方法使用ApplicationPools内部
  • ApplicationPools立即在构造 IQueryable 时再次使用,该 IQueryable 立即使用(但未完全执行 -foreach语句使用yield return内部)并过滤。
  • Call to .Start()改变(变异)的状态ApplicationPool所引用的ServerManager对象引用
  • 其余部分不相关,因此循环返回到开头。它仍然使用相同的ServerManager。由于该引用已改变状态(因为调用.Start()),它可能会被 GC 标记并且从未被收集 - 应用程序池永远不会在后续迭代的结果中返回,并且可能导致内存中引用的孤立。

这只是一个假设,请记住!

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