Process memory increases much faster with gflags +ust

Question

I've got stuck in a problem with gflags when trying to find some memory leaks in a windows app.

When I turn on the ust flag (in order to collect memory allocations stack traces) the memory of my application increases much faster than it does when the flag is off (it reaches to 800MB in 10 min aprox. which is far from the 50-100MB/day I get when the flag is off).

I've read that there is a maximum for stack traces of 32MB, so I suppose this shouldn't be a problem.

The computer is a 4x Intel(R) Xeon(R) CPU E5410 @ 2.33GHz.

If someone could give me some hint I'd really appreciate it.

Thank you!

Answer 1

The stack trace database is not the only impact of the ust flag. It also adds at least 32 bytes to each allocation, in order to store its stack trace id. This could explain your memory increase if lots of small allocations are involved. If you launch the process with an attached debugger or compiled the process with debug target, the windows heaps will be set in debug mode and the overhead per allocation will be even bigger.

Answer 2

You can set the maximum trace database size using /tracedb SizeInMB See the MSDN Gflags documentation for chapter and verse. By default there is no maximum size which most likely explains the behaviour you have seen.