Use UMDH to identify memory leak problem

Use UMDH to identify memory leak problem

原文链接：https://www.thinksaas/group/topic/634356/

We sometimes got memory leak problem, and we need to find the leaked memory, Here is a usful tool from MS, UMDH, it is included in WinDBG install package.

It need the PDB files to analyse access the symbol table, then a human readable stack can be generated.
You need to generated two set of current used memory, and compare the two to have a result.
It compares the current used memory, so you can identify the still-in-use memory, That is the memory you stored somewhere, but they will actually never be used again, and should be released.
And of cause, it can identify the memory with out a ptr pointing to when comparing.
You should let memory leak a little more to get a clear view of the result.
Here is the steps to use UMDH:
1. Install Windbg, you can get WinDBG from MS site:http://msdn.microsoft/en-us/windows/hardware/hh852365
2. Open a Dos Prompt as Administrator and navigate to the installation folder of WinDbg
3. Set Symbol Path as a System Variable

set _NT_SYMBOL_PATH= SRV*C:websymbols*http://msdl.microsoft/download/symbols; c:xosymbol

1. Download PDB file and copy to the “C:xosymbol” which is set part of above environment variable “_NT_SYMBOL_PATH”

2. Start collecting stack traces for user-mode allocations, run command:
   gflags /i +ust

3. Restart your process.

4. Keep it running, wait until it become steady..

5. Collect a baseline snapshot, run command:
   umdh -pn: -f:c:1.log

6. Wait until the memory usage of your process exceeds 1GB or more.

7. Generate a new snapshot, run command:
   umdh -pn: -f:c:2.log

8. Compare the two snapshots and get the final report from UMDH
   umdh -d c:1.log c:2.log > c:
   esult12.log

9. In the result, we can see the stack where the leaked memory is allocated, You got a direct hint to resolve the leak problem.
   And if you need an example, please go to page https://www.hyzblog/use-umdh-identify-memory-leak-problem/