PerfView无法访问的内存

Question

我正在调查我们有一个wcf应用程序的内存问题，我正在使用perfview来挖掘内存。我们获得了基础快照，然后获得了内存高时的快照。我对它们进行了分析，并查看了我在2921MB处看到的未获取内存的数据。我的理解是，未获得的记忆意味着它已经准备好了GC'd。它已经超过16小时，无法访问的内存不断攀升。

什么会导致GC不收集无法访问的内存？

UPDATE

我能得到终结队列的转储当服务消费显著内存。我在这份报告中究竟应该寻找什么？或者也许应该运行其他windbg/sos/sosex命令？

0:037> !finalizequeue 
SyncBlocks to be cleaned up: 0 
Free-Threaded Interfaces to be released: 0 
MTA Interfaces to be released: 0 
STA Interfaces to be released: 0 
---------------------------------- 
------------------------------ 
Heap 0 
generation 0 has 464 finalizable objects (0000000033877190->0000000033878010) 
generation 1 has 52 finalizable objects (0000000033876ff0->0000000033877190) 
generation 2 has 19958 finalizable objects (0000000033850040->0000000033876ff0) 
Ready for finalization 228791 objects (0000000033878010->0000000033a36dc8) 
------------------------------ 
Heap 1 
generation 0 has 1508 finalizable objects (000000002ee2e168->000000002ee31088) 
generation 1 has 91 finalizable objects (000000002ee2de90->000000002ee2e168) 
generation 2 has 23498 finalizable objects (000000002ee00040->000000002ee2de90) 
Ready for finalization 249421 objects (000000002ee31088->000000002f0182f0) 
------------------------------ 
Heap 2 
generation 0 has 66 finalizable objects (00000000292660d0->00000000292662e0) 
generation 1 has 63 finalizable objects (0000000029265ed8->00000000292660d0) 
generation 2 has 19411 finalizable objects (0000000029240040->0000000029265ed8) 
Ready for finalization 238531 objects (00000000292662e0->00000000294380f8) 
------------------------------ 
Heap 3 
generation 0 has 510 finalizable objects (0000000034e470d8->0000000034e480c8) 
generation 1 has 77 finalizable objects (0000000034e46e70->0000000034e470d8) 
generation 2 has 19910 finalizable objects (0000000034e20040->0000000034e46e70) 
Ready for finalization 226933 objects (0000000034e480c8->0000000035003470) 
Statistics for all finalizable objects (including all objects ready for finalization): 
       MT Count TotalSize Class Name 
000007fe9c64aba8  1   24 System.Threading.OverlappedDataCache 
000007fe9af40ea0  1   24 System.Web.Configuration.ImpersonateTokenRef 
000007fea03a8640  1   32 System.IO.Compression.ZLibNative+SafeLibraryHandle 
000007fe9dd14820  1   32 Microsoft.Win32.SafeHandles.SafeCspHandle 
000007fe9d302a50  1   32 Microsoft.Win32.SafeHandles.SafePEFileHandle 
000007fe9cf161a8  1   32 Bid+AutoInit 
000007fe9cbead60  1   32 Microsoft.Win32.SafeHandles.SafePerfProviderHandle 
000007fe9c69a200  1   32 System.Net.SafeLocalFree 
000007fe9c649080  1   32 System.ServiceModel.Channels.PipeHandle 
000007fe9c62ad18  1   32 System.Net.SafeInternetHandle 
000007fe9af42a08  1   32 Microsoft.Win32.SafeHandles.SafeFileMappingHandle 
000007fe9af42920  1   32 Microsoft.Win32.SafeHandles.SafeViewOfFileHandle 
000007fe9ad790b0  1   32 System.Web.PerfInstanceDataHandle 
000007fe9c4b08d8  1   40 System.Security.SafeBSTRHandle 
000007fe9ce69118  1   48 System.Runtime.CompilerServices.ConditionalWeakTable`2[[System.Transactions.ContextKey, System.Transactions],[System.Transactions.ContextData, System.Transactions]] 
000007fe9c62cf68  1   48 System.Runtime.IOThreadScheduler 
000007fe9af0d5f8  1   48 Microsoft.CSharp.CSharpCodeProvider 
000007fe9ae4c628  1   48 System.Runtime.CompilerServices.ConditionalWeakTable`2[[System.Object, mscorlib],[System.Runtime.Serialization.SerializationInfo, mscorlib]] 
000007fe9af43750  1   56 System.Web.Compilation.CompilationMutex 
000007fe9ae45a60  2   64 System.Security.Cryptography.SafeProvHandle 
000007fe9a91bad0  2   64 System.Threading.TimerQueue+AppDomainTimerSafeHandle 
000007fea03adee0  2   96 System.Web.Security.FileSecurityDescriptorWrapper 
000007fe9d669608  3   120 System.Threading.RegisteredWaitHandleSafe 
000007fe9c623850  3   120 System.Net.SafeRegistryHandle 
000007fe9c696808  4   128 System.Gen2GcCallback 
000007fe9a97d6b0  4   128 Microsoft.Win32.SafeHandles.SafeFileHandle 
000007fe9d8710a0  1   160 System.Threading.CdsSyncEtwBCLProvider 
000007fe9c64b368  1   160 System.Collections.Concurrent.CDSCollectionETWBCLProvider 
000007fe9c648d08  1   160 System.PinnableBufferCacheEventSource 
000007fe9be65a08  5   160 Microsoft.Win32.SafeHandles.SafeProcessHandle 
000007fe9f557760  1   168 System.Web.AspNetEventSource 
000007fe9acab410  2   176 System.Runtime.Diagnostics.EtwProvider 
000007fe9ad7daa0  8   192 System.SizedReference 
000007fe9aac5d38  2   208 System.Runtime.Remoting.Contexts.Context 
000007fe9e5a7c58  1   216 log4net.Appender.RollingFileAppender 
000007fe9c64a138  2   224 System.ServiceModel.Channels.OverlappedContext 
000007fe9cbe45c8  3   264 System.Diagnostics.PerformanceData.CounterSet 
000007fe9cda2278  9   288 System.Net.SafeCloseHandle 
000007fe9c628078  6   288 System.Net.SafeCloseSocketAndEvent 
000007fe9ad05090  2   320 System.Diagnostics.Tracing.FrameworkEventSource 
000007fe9c4be5a0  2   352 System.Data.DataSet 
000007fe9c69ee18  3   360 System.Net.TlsStream 
000007fe9a97cf10  4   416 System.IO.FileStream 
000007fe9a8afc60  14   448 Microsoft.Win32.SafeHandles.SafeRegistryHandle 
000007fe9ad05940  6   528 System.Diagnostics.Tracing.EventSource+OverideEventProvider 
000007fe9c714d60  18   576 System.Net.SafeFreeContextBuffer_SECURITY 
000007fe9c628d68  19   608 System.Net.SafeNativeOverlapped 
000007fe9cbe49d8  14   672 System.Diagnostics.PerformanceData.CounterSetInstanceCounterDataSet 
000007fe9ae78550  10   720 System.Web.DirMonCompletion 
000007fe9cbe4880  14   784 System.Diagnostics.PerformanceData.CounterSetInstance 
000007fe9f2d6db8  12   864 NewRelic.Agent.Core.Wrapper.AsyncAgentWrapperApi.Builders.TransactionBuilder 
000007fe9bcb8250  27   864 System.Net.SafeCloseSocket+InnerSafeCloseSocket 
000007fe9c6947e0  3   888 System.Net.Connection 
000007fe9bcb9d18  28   1120 System.Net.SafeCloseSocket 
000007fe9ad7bef8  35   1120 Microsoft.Win32.SafeHandles.SafeWaitHandle 
000007fe9c2de460  3   1536 System.Data.DataTable 
000007fe9c7dee68  62   2480 System.Net.SafeFreeContextBufferChannelBinding_SECURITY 
000007fe9cf19418  12   2592 System.Data.DataColumn 
000007fe9bcb6b38  28   3808 System.Net.Sockets.Socket 
000007fe9c7196c0  120   3840 System.Security.Cryptography.SafeCertChainHandle 
000007fe9c695b60  62   3968 System.Net.Sockets.NetworkStream 
000007fe9c711618  62   4960 System.Net.Security._SslStream 
000007fe9c718cf8  179   7160 System.Net.SafeCredentialReference 
000007fe9c74c9d8  240   7680 System.Security.Cryptography.SafeCertStoreHandle 
000007fe9d406ff8  377   9048 System.Reflection.Emit.DynamicResolver+DestroyScout 
000007fe9dc33bd0  342  10944 System.Security.Cryptography.SafeKeyHandle 
000007fe9cda9d00  25  11400 System.Net.Sockets.SocketAsyncEventArgs 
000007fe9f4c7440  532  17024 Devart.Common.o 
000007fe9f4e2e90  350  22400 Devart.Data.Oracle.OracleCursor 
000007fe9c5e4eb8  651  26040 System.Threading.ThreadPoolWorkQueueThreadLocals 
000007fe9f448870  792  31680 Microsoft.Practices.EnterpriseLibrary.Caching.Cache 
000007fe9f4c5d40  151  41072 Devart.Data.Oracle.a3 
000007fe9f4e0fd8  191  41256 Devart.Data.Oracle.OracleDataReader 
000007fe9f3ce7d0  191  44312 Devart.Data.Oracle.OracleCommand 
000007fe9c661238  1445  46240 System.Security.Cryptography.SafeHashHandle 
000007fe9aaa67e0  1985  47640 System.WeakReference 
000007fe9ce69d70  2193  70176 System.Transactions.SafeIUnknown 
000007fe9c71c040  2593  82976 System.Security.Cryptography.X509Certificates.SafeCertContextHandle 
000007fe9a756f58  1932  123648 System.Threading.ReaderWriterLock 
000007fe9c74f038  4788  153216 System.Security.Cryptography.SafeLocalAllocHandle 
000007fe9c749bf0  5244  167808 System.Security.Cryptography.SafeCertContextHandle 
000007fe9a706568  1942  186432 System.Threading.Thread 
000007fe9fcf5df0  1692  243648 Devart.Data.Oracle.dz 
000007fe9c71c118  6667  320016 System.Net.SafeFreeCredential_SECURITY 
000007fe9a9190e0 15031  360744 System.Threading.TimerHolder 
000007fe9be64d58  2328  651840 System.Diagnostics.Process 
000007fe9f440548 14217  1023624 Microsoft.Practices.EnterpriseLibrary.Common.Configuration.Storage.ConfigurationChangeFileWatcher 
000007fe9ce6a6e8 14217  1364832 System.Timers.Timer 
000007fe9c71c918 29980  1678880 System.Net.SafeDeleteContext_SECURITY 
000007fe9a94dd68 89958  3598320 Microsoft.Win32.SafeHandles.SafeLocalAllocHandle 
000007fe9a91b268 185991  5951712 Microsoft.Win32.SafeHandles.SafeTokenHandle 
000007fe9ad0b578 206499  14867928 System.Reflection.Emit.DynamicResolver 
000007fe9f3ca188 435920  87184000 Devart.Data.Oracle.OracleConnection 
Total 1029284 objects 

“准备完成”对象的数量对我来说很重要。不应该是零，或至少少于几百？

Answer 1

如果您将错误应用IDisposable，GC将不会收集内存。根据截图，你提供的，你
1.没有关闭连接到Oracle数据库（我谈到Devart.Data.Oracle ....片段）。不要依赖oracle db连接的密切方法，而应考虑使用using运算符，它将为您提供确定性的垃圾回收。
2.提到DynamicResolver的第二行指向了某种依赖注入。从我的经验来看，我认为你的依赖注入库不知道如何清理你的对象。这实际上可以通过为您的类实现IDisposable接口来解决，这是DI库使用的接口。
3.第三线，其中有以下子：Win32.SafeHandles.SafeTokenHandle给出了大概你使用一些系统资源，或一些.NET领域也经常称为非托管资源之外的暗示。对于他们，您需要实施内存清理和IDisposable以及Finalizer连接。有关更多详细信息，请参阅此link。

Answer 2

它已经超过16个小时，无法访问的内存不断攀升。 什么会导致GC不收集无法访问的内存？

当任何一代中的对象的大小运行特定阈值时，GC将运行。下面是一些近似的值：

• 代0的命中〜256千
• 创1次命中〜2 MB（第0级和第1代收集）
• Gen 2次的命中〜10 MB（第0级， 1代和2代收集）
• 操作系统发送一个低内存通知
• GC.Collect的（）被调用（这不只是特殊情况下是个好主意）

你的应用A n内存在2,921MB，所以下一次收集不会发生一段时间。自从GC不以每秒x秒/分钟/小时的速度运行，而是基于上述条件运行16或1600小时无关紧要。

要问自己的一个更好的问题是要明白为什么这些对象不会被收集到Gen 0集合中。找出Gen 0中没有收集哪些物体，然后问问自己：这些物体是否真的需要这么长时间？。

1. 请确保您在不需要的时候尽快处置对象。
2. 请勿将物体放置在比他们需要的时间更长的地方。