Valgrind is a tool for memory debugging, memory leak detection, and profiling. It is essentially a virtual machine using just-in-time compilation techniques.
The Valgrind distribution currently includes five production-quality tools: a memory error detector, a thread error detector, a cache and branch-prediction profiler, a call-graph generating cache profiler, and a heap profiler. It also includes two experimental tools: a data race detector, and an instant memory leak detector.
Valgrind is designed to be as non-intrusive as possible. It works directly with existing executables. You don’t need to recompile, relink, or otherwise modify, the program to be checked.
- Memcheck detects memory-management problems in programs. All reads and writes of memory are checked, and calls to malloc/new/free/delete are intercepted. Memcheck can therefore detect the following problems:
- Use of uninitialised memory.
- Reading/writing memory after it has been free’d.
- Reading/writing off the end of malloc’d blocks.
- Reading/writing inappropriate areas on the stack.
- Memory leaks — where pointers to malloc’d blocks are lost forever.
- Mismatched use of malloc/new/new  vs free/delete/delete .
- Overlapping src and dst pointers in memcpy() and related functions.
- Cachegrind is a cache profiler. It performs detailed simulation of the I1, D1 and L2 caches in your CPU and so can accurately pinpoint the sources of cache misses in your code. It will show the number of cache misses, memory references and instructions accruing to each line of source code, with per-function, per-module and whole-program summaries. If you ask really nicely it will even show counts for each individual machine instruction.
- Callgrind is a profiler similar in concept to Cachegrind, but which also tracks caller-callee relationships. By doing so it is able to show how instruction, memory reference and cache miss costs flow between callers and callees. Callgrind collects a large amount of data which is best navigated using Josef Weidendorfer’s amazing KCachegrind visualisation tool. KCachegrind is a KDE application which presents these profiling results in a graphical and easy-to-understand form.
- Massif is a heap profiler. It measures how much heap memory programs use. In particular, it can give you information about heap blocks, heap administration overheads, and stack sizes.
- Helgrind detects synchronisation errors in programs that use the POSIX pthreads threading primitives. It detects the following three classes of errors:
- Misuses of the POSIX pthreads API.
- Potential deadlocks arising from lock ordering problems.
- Data races — accessing memory without adequate locking.
Developer: Cerion Armour-Brown, Jeremy Fitzhardinge, Tom Hughes, Nicholas Nethercote, Paul Mackerras, Dirk Mueller, Julian Seward, and others
License: GNU General Public License v2.0
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