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我正在运行一个为 HTTP 请求提供服务的 C# 应用程序。我最近注意到它占用的内存比我预期的要多。我抓了一些转储，在 Windbg 中弹出，发现大部分内存都标记为 Free：

!dumpheap -stat
...
00007ffde4783630   681599     65433504 System.Threading.Tasks.TaskFactory+CompleteOnInvokePromise
00007ffde47cc988   167885     76872908 System.Byte[]
00007ffde47c6948   521353     80352802 System.String
0000007e3a16c2d0  1870425   1415374334      Free

因此转储约为 3GB，因此其中大约一半是可用内存。看着堆，我看到了这个：

!heapstat
Heap             Gen0         Gen1         Gen2          LOH
Heap0        82248472      7354560    987275056    178834656
Heap1        93146552      6382864    857470096    129435960
Total       175395024     13737424   1844745152    308270616

Free space:                                                 Percentage
Heap0        40969256       146456    640426720     54829792 SOH: 63% LOH: 30%
Heap1        75943736        94448    550812312     54825216 SOH: 65% LOH: 42%
Total       116912992       240904   1191239032    109655008

所以我的小对象堆非常分散，特别是 Gen2。在服务器上，我可以看到正在发生 gen2 集合（使用性能计数器），但即使它们是，看起来 gen2 堆也没有被压缩。即使服务器上只有 1-2% 的 RAM 可用，gen2 堆也不会被压缩。

对我来说，看起来我正在承受这种内存压力，因为堆是碎片化的。但是我无法弄清楚为什么会发生碎片或为什么 gen2 无法被压缩。一些可用空间的大小为 6MB，所以我认为它肯定会压缩这些空间。

谁能给我一些关于如何弄清楚为什么我的堆如此分散的想法？我什至在这里吠叫正确的树吗？

任何帮助将不胜感激，谢谢！

编辑1：

细分!gchandles为：

Handles:
Strong Handles:       4507
Pinned Handles:       58
Async Pinned Handles: 977
Ref Count Handles:    1
Weak Long Handles:    6087
Weak Short Handles:   724
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1 回答 1

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The next step would be to use !gchandles and look for pinned handles. This might identify objects that are locked to a specific memory position, because some native code (e.g. C++) needs to access it. While garbage colelction may move objects around in memory, the C++ pointer will not be updated by .NET, so pinning is the only option.

Even when there is only 1-2% of RAM available on the server the gen2 heap is not being compacted.

You're talking about physical RAM here. From an operating system, I expexct that it uses the available resources as good as possible, so I expect the RAM to be 100% used at all the time. If it is "not used", I expect the OS to use it for caching. Due to this, the physical RAM usage cannot really be an indicator for garbage collection.

Also, I would not worry too much. If the memory is not used by .NET, it will be swapped to disk by the OS and thus free physical RAM for other purposes.

于 2017-11-25T15:50:31.747 回答