Enterprise Library Test Guide - Willy .Net

Testing for Performance and Scalability 237
HashProviderFactory factory = new HashProviderFactory();
IHashProvider hashProvider = factory.Create("hashprovider");
hashProvider.CreateHash(b);
System.GC.Collect();
}
Next, run the test again until the performance counters register the suspicious behavior.
You can now use WinDbg to find and troubleshoot the memory leak.
To use WinDbg
1. On the taskbar, click Start, point to All Programs, point to Debugging Tools for
Windows, and then click WinDbg. WinDbg starts.
2. Because ASP.NET hosts the application block, you must attach the debugger to
w3wp.exe. On the File menu, click Attach to Process. The Attach to Process list
box appears. Click the By Executable option button. Click w3wp.exe. Click OK.
After performing these steps, load the SOS extension to WinDbg. Open a command
window in the debugger and type:
!loadby sos mscorwks
Next, look at the heap. Type:
!dumpheap -stat
This command reports all the managed objects that are currently in the heap, sorted
by number of allocations and size. The MT column, where MT stands for Method
Table, lists the pointers to the tables that describe the objects. The Count column lists
the number of objects that exist in the heap for each type of object. The TotalSize column
lists the amount of memory that is being used by any one type of object. The last
column is the fully typed name of the object.
MT Count TotalSize Class Name
029b0800 11502 138024 Microsoft.Practices.EnterpriseLibrary.
Caching.Expirations.NeverExpired
79124670 193 229708 System.Char[]
79124228 12721 340908 System.Object[]
029b06d4 11501 460040 Microsoft.Practices.EnterpriseLibrary.Caching.
CacheItem
790fa3e0 20210000 93908800 System.String
791242ec 140 14656992 System.Collections.Hashtable+bucket[]
The suspicious entries have the largest counts and the largest sizes.
Assume that the number of System.String objects appears suspicious. The memory
dump says that there are 20210000 of those objects. This appears too high.
You need to look at MT location 790fa3e0. Type:
!dumpheap -mt 790fa3e0