Microsoft.Web.Administration内存泄漏 [英] Microsoft.Web.Administration memory leak

问题描述

具有Windows服务，该服务除其他外还监视IIS应用程序池.如果任何池已配置了应用程序且未运行，则将启动该池(池).一段时间以来，它一直运行良好.最近发现该服务正在泄漏内存.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.唯一可抛弃的对象是ServerManager，我在using块中拥有它.已经找到有关此泄漏的其他报告，但尚未解决.(请参见 http://msdn.microsoft.com/zh-CN/library/microsoft.web.administration.servermanager(v = vs.90).aspx#CommunityContent )

Have a windows service that, amongst other things, monitors IIS application pools. If any pool is has configured applications and is not running, it (the pool) is started. This has been working fine for some time. It was recently discovered that the service was leaking memory. Looking at a memory dump the culprit is the Microsoft.Web.Administration used to check the application pools. The only object that's disposable is ServerManager and I have that in a using block. Have found other reports of this leak but no solution yet. (see user comments in http://msdn.microsoft.com/en-us/library/microsoft.web.administration.servermanager(v=vs.90).aspx#CommunityContent)

转储Microsoft.Web.Administration.ServerManager的所有根(此转储中为481)时，我只能看到其中一个根.假设这是当前迭代.

When dump all the roots for Microsoft.Web.Administration.ServerManager (481 in this dump) I only see roots one of them. Assume this is the current iteration.

不确定为什么这些Web.Administration对象无法被收集，即使它们似乎没有被植根(?).关于如何解决此泄漏的任何想法?

Not sure why these Web.Administration objects cannot be collected, even though they don't seem to be rooted(?). Any ideas on how to plug this leak?

我将代码移至控制台应用程序，并在那里复制了漏洞.

I moved the code to a console application and reproduced the leak there.

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.

推荐答案

当我第一次阅读该问题时，我想到的第一件事是，可以通过使用

When I first read the question, the first thing that occurred to me was that this whole issue could possibly be avoided entirely by using the Windows Activation Service (WAS).

我对您发布的代码的第一次浏览使我感到，您的问题可能与访问/修改由 foreach 循环创建的各种闭包有关.

My first pass through the code that you posted gave me the feeling that your issue could be related to accessing/modifying of the various closures that are being created by the 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或失败的原因，从而提供了更多有关根本原因的信息:

Try these small refactorings and see if any/all are able to reduce or eliminate the problem or failing that, provides more info on the root cause:

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

3. 由于您仅使用 ApplicationPool.Name ，因此请进行以下重构:

1. avoid deferred execution of your LINQ queries by calling .ToList() immediately
2. Instead of re-using the ServerManager object, create a new one on each iteration of the loop

3. Since you're only using ApplicationPool.Name, refactor this:

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

对此:

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

我的假设是这是正在发生的事情

My hypothesis is that this is what is happening:

• 在 using 语句中创建 ServerManager 的新实例
在该对象引用上调用
• 静态扩展方法，该对象引用在内部使用 ApplicationPools
• ApplicationPools 立即在IQueryable的构造中再次使用，该IQueryable立即使用(但未完全执行- foreach 语句使用 yield return 内部)并进行过滤.
• 调用 .Start()更改(突变) ServerManager 对象引用
引用的 ApplicationPool 的状态.
• 其余部分无关紧要，因此循环可追溯到开始.它仍然使用相同的 ServerManager .由于该引用的状态已发生变化(由于调用了 .Start())，因此它可能已被GC标记并且从未收集过-在后续迭代的结果中永远不会返回该应用程序池，并且可能会导致内存中的引用孤立.

• New instance of ServerManager is created in the using statement
• Static extension method is called on that object reference, which uses ApplicationPools internally
• ApplicationPools is immediately used again in the construction of an IQueryable, which is immediately used (but not fully executed -- foreach statements use the yield return internally) and filtered.
• Call to .Start() changes (mutates) state of the ApplicationPool referenced by the ServerManager object reference
• the rest isn't relevant, so the loop goes back to the beginning. It still uses the same ServerManager. Since that reference has mutated state (because of call to .Start()), it may be getting flagged by the GC and never collected - that app pool is never returned in the results of subsequent iterations, and may cause orphaning of the reference in memory.

请记住，这只是一个假设！

This is just a hypothesis, keep in mind!

这篇关于Microsoft.Web.Administration内存泄漏的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！