Looking for a way to detect valgrind/memcheck at runtime without including valgrind headers

Question

Valgrind/Memcheck can be intensive and causes runtime performance to drop significantly. I need a way (at runtime) to detect it in order to disable all auxiliary services and features in order to perform checks in under 24 hours. I would prefer not to pass any explicit flags to program, but that would be one way.

1. I explored searching the symbol table (via abi calls) for valgrind or memcheck symbols, but there were none.
2. I explored checking the stack (via boost::stacktrace), but nothing was there either.

Answer 1

Not sure it's a good idea to have a different behavior when running under Valgrind since the goal of Valgrind is to assert your software in the expected usage case.

Anyway, Valgrind does not change the stack or symbols since it (kind of) emulates a CPU running your program. The only way to detect if you're being run under Valgrind is to observe for its effects, that is, everything is slow and not multithreaded in Valgrind.

So, for example, run a test that spawn 3 threads consuming a common FIFO (with a mutex/lock) and observe the number of items received. In real CPU, you'd expect the 3 threads to have processed close to the same amount of items in T time, but when run under Valgrind, one thread will have consumed almost all items in >>T time.

Another possibility is to call a some known syscall. Valgrind has some rules for observing syscall. For example, if you are allocating memory, then Valgrind will intercept this block of memory, and fill that memory area with some data. In a good software, you should not read that data and first write to it (so overwriting what Valgrind set). If you try to read that data and observe non zero value, you'll get a Valgrind invalid read of size XXX message, but your code will know it's being instrumented.

Finally, (and I think it much simpler), you should move the code you need to instrument in a library, and have 2 frontends. The "official" frontend, and a test frontend where you've disabled all bells and whistles that's supposed to be run under Valgrind.