valgrind

memory debugger and profiler
Valgrind is a GPL'd tool to help you find memory-management problems in your
programs. When a program is run under Valgrind's supervision, all reads and
writes of memory are checked, and calls to malloc/new/free/delete are
intercepted.
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Valgrind can debug more or less any dynamically-linked ELF x86/Linux,
amd64/Linux and ppc/Linux executables, without modification, recompilation,
or anything.
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Valgrind provides a generic infrastructure for supervising the execution of
programs called "tools". This is done by providing a way to instrument
programs in very precise ways, making it relatively easy to support
activities such as dynamic error detection and profiling. The Valgrind
distribution currently includes three tools: a memory error detectors, a
cache (time) profiler and a heap (space) profiler.