How to research unmanaged memory leaks in .NET?

Question

I have a WCF service running over MSMQ. Memory gradually increases over time, indicating that there is some sort of memory leak. I ran the service locally and monitored some counters using PerfMon. Total CLR memory managed heap bytes remains relatively constant, while the process' private bytes increases over time. This leads me to believe that there is some sort of unmanaged memory leak. Assuming that unmanaged memory leak is the issue, how do I address the issue? Are there any tools I could use to give me hints as to what is causing the unmanaged memory leak? Also, all my service is doing is reading from the transactional queue and writing to a database, all as part of a DTC transaction (handled under the hood by requiring a transaction on the service contract). I am not doing anything explicitly with COM or DllImports.

Thanks in advance!

Solution 1

You can use Windbg to analyze the process Heap. There are some articles and cheat sheets showing how to do this, like Memory Leak Detection Using Windbg

Solution 2

This blog will help you if you are willing to learn about windbg (http://www.microsoft.com/whdc/devtools/debugging/default.mspx).

http://blogs.msdn.com/tess/default.aspx

Solution 3

Make sure that you close the service client after using it. something like

try {
... do work ...
Close();
} ... exception handling ... {
Abort();
}

Comments

[Basic]

Do the Close in the finally block - that way it will happen even if there is an exception...