Environment.WorkingSet bug

Environment.WorkingSet returns the working set incorrectly for my asp.net application which is the only application in its application pool.

On a Windows 2003 Server SP2 with 3GBs of Ram which is a VMWare Virtual Machine, it reports working set as 2.047.468.061 bytes(1952MBs) and Process.WorkingSet value is 75.563.008 bytes(72MBs).

• Memory Status values returned by GlobalMemoryStatusEx:

AvailExtendedVirtual : 0 
AvailPageFile: 4.674.134.016 
AvailPhys: 2.140.078.080 
AvailVirtual: 1.347.272.704 
TotalPageFile: 6.319.915.008 
TotalPhys: 3.245.568.000 
TotalVirtual: 2.147.352.576  

• GetProcessMemoryInfo()

Working Set : 55.140.352 
Peak Working Set: 75.571.200 
PageFile : 94.560.256 
QuotaPagedPoolUsage : 376.012 
QuotaNonPagedPoolUsage : 33.261  

• GetProcessWorkingSetSize() - min : 204.800 - max : 1.413.120

• GetPerformanceInfo()

CommitLimit : 1.542.948 pages 6.319.915.008 bytes  
CommitPeak : 484.677 pages 1.985.236.992 bytes  
CommitTotal : 417.514 pages 1.710.137.344 bytes  
HandleCount : 57.012  
KernelNonpaged : 8.671 pages 35.516.416 bytes  
KernelPaged : 27.302 pages 111.828.992 bytes  
KernelTotal : 35.973 pages 147.345.408 bytes  
PageSize : 4.096 bytes  
PhysicalAvailable : 508.083 pages 2.081.107.968 bytes  
PhysicalTotal : 792.375 pages 3.245.568.000 bytes  
ProcessCount : 43  
SystemCache : 263.734 pages 1.080.254.464 bytes  
ThreadCount : 1.038  

After loding the new patch, http://support.microsoft.com/kb/983583/en-us, .NET Version changes to 2.0.50727.3615 and Environment.WorkingSet now returns the value: 2.047.468.141.(which is 80 bytes bigger than previous one)

On a Vista machine with 3GBs of Ram, Environment.WorkingSet and Process.WorkingSet values are similar and around 37 MBs.

So, why Environment.WorkingSet returns a fixed value? Restarting the application pool does not change anything, it always return the same magic value, 2.047.468.061.

I have also setup an .NET 1.1.4322.2443 application, and it weirdly WorkingSet is returned a number from a random set of unrelated numbers(193.654.824, 214.101.416, 57.207.080, 287.635.496) each time page refreshed while GetProcessMemoryInfo() returns the expected number.

I have also found that when the application run by impersonating "NT AUTHORITY\NetworkService" account this problem does not occur, Environment.WorkingSet returns the expected number both .net v1.1 and v2.0.

I have checked CodeAccessPermissions like E开发者_JS百科nvironmentPermission for windows user and NetworkService but could not find anything that restricts reading the WorkingSet value.

So, what could cause this? Is it a bug, some incorrect configuration or corrupt file etc.?

Environment.WorkingSet is a "estimation" by the CLR on the memory space needed by your application. If your application does not change (physically) then it should be the same value on every load (I cannot verify that 100%, but it should be correct enough to proceed.).

It is always bigger than is actually needed as it is unsure of the code branches required, but the OS will reduce the memory if it sees it is not being used. A good example is to minimise the application to the taskbar to see it reduce in size.