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Memory Checker Tools For C++?
An anonymous reader writes "These newfangled memory-managed languages like Java and C# leave an old C++ dev like me feeling like I am missing the love. Are there any good C++ tools out there that do really good memory validation and heap checking? I have used BoundsChecker but I was looking for something a little faster. For my problem I happen to need something that will work on Windows XP 64. It's a legacy app so I can't just use Boosts' uber nifty shared_ptr. Thanks for any ideas."
boost::shared_ptr is not a memory checker, it's a reference-counted smart pointer, and works fine in legacy apps (such as compiled under VC++ 6).
This isn't really an answer to your question, but it's on topic and there's some questions I wanted to get answered myself.
First of all, shared_ptr is going into the standard library as part of TR1. Does anyone know when common development environments, i.e. GCC and MSVC, will start including TR1?
Second, I believe that there are a number of garbage collectors available as libraries for C++. I've heard boehm's garbage collector mentioned numerous times. My question is, are any of these libraries any good? Are they really practical to use in real world applications? Do you have to modify all of your types to use it, or can primitive and stl types work with it?
Yep, Paul Nettle's little memory manager rocks. It WILL find leaks in your program. http://www.paulnettle.com/ (Yes, you have to navigate through a horrible flash site to get it, but it's worth it).
I know this isn't exactly what the article is looking for. But, if you are using the STL (which you SHOULD be!) you may be interested to know that the STLPort STL implementation includes a debug mode which contains loads of error checking to make sure you aren't misusing STL.
They might be useful for small apps but if you have a massive app they are almost more trouble than they are worth.
It's hard to say what you can do except foster safe coding practice and highlight the common pitfalls such as memory leaks, buffer overflows etc. Many compilers can help detect heap / memory overruns because the debug libs put guard bytes on the stack & heap that trigger exceptions when something bad happens. There are also 3rd party libs such as Boehm which help with memory leeak / garbage collection issues and dump stats. I'd say using STL & Boost is also a very good way of minimizing errors too simply because doing so avoids having to write your own implementations of arrays, strings etc. which are bound to be less stable.
Talk about a sledgehammer to crack a nut. Boost strikes me as the sort of library used by people who want to show off how up to date their skills are , not people who really need to write a program to get a job done. Its bloated , has a wierd syntax that differs from the C++ norm and doesn't solve any problem that isn't already solved or could be done quite easily by standard C++ anyway. What is its point except as intellectual masturbation by its authors? No this isn't a Troll, this is a post by someone who was forced to use Boost for a year and I loath it. Yeah , mod me down , whatever...
PageHeap is a debugging tool for Windows created by Microsoft. It does what you want.
For more information look here:
http://support.microsoft.com/kb/286470
Use valgrind : www.valgrind.org It is (in my opinion) the best tool available for this purpose. In fact, I develop C++ exclusively on linux first because of valgrind, then port to Win32 later. By the way, you're not missing out on anything special by not programming in Java or C#. Both of those languages are slow, and introduce their own language complexities. -bms20
I haven't used it for a while, but I used to use Bruce Peren's efence for bits of malloc debugging, it hasn't been actively developed for ages but it's pretty light weight if that's what you need. There appears to be an up to date branch DUMA which I haven't tried. As far as I remember you can use efence under WIN and DUMA claims to work......
Unfortunately, what you prolly want is valgrind or purify.
Hmmmmmm
I have tried mainly Boundschecker and Purify, and they were usually quite slow and difficult to set up and produced lots of spurious results. Also, quite often they simply didn't work at all and refused to run certain programs. A few years ago I reduced the problem to a 10 line C++ program that would crash Boundschecker or Purify, can't remember anymore which one it was.
o r.asp
In any case, Visual Leak Detector is a free memory checking tool. It's only for Windows / Visual Studio, but if you are using that, VLD is awesome: http://www.codeproject.com/tools/visualleakdetect
It's super easy to set up, just #include "vld.h" somewhere in your program, and then run the debug mode. No need to rebuild everything in instrumented mode, and no false results (at least I haven't got any). Real memory leaks will be reported in the output window of the IDE.
If you use MS compilers the memory debug stuff is in crtdbg.h, IIRC it has been there in one form or another since V1.5 but for some reason seems too obscure for the average Windows programmer to find. ;)
It is a very handy feature for finding leaks, buffer overflows, ect. The only other product I've used to find memory problems on recent incarnations of Windows is Purify. The MS solution is infinitely simpler because it's built into the environment and it's narrowly focused on memory problems. To state the obvious and in fairness to Purify, MSDev is infuriatingly fussy when it comes to building debug modules for IBM's Purify.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
I used to select tools for my team. For UNIX, I selected Purify and for Windows, BoundsChecker. After a few days with BoundsSlacker, **all** and I mean every one of my team was asking for Purify for Windows licenses. 17 licenses later and our code crashes have dropped byat least 90%.
Yes, it isn't cheap. Just do it. You'll thank me.
The productivity increase alone will make it worthwhile for management.
Valgrind's default memcheck tool is an excellent way of finding memory errors - ranging from extremely subtle to obvious. In addition, Valgrind can be used as a code profiler, cache simulator and many other things. It really is an excellent tool - I recommend it to anybody writing C++.
"It is better to die for an idea that will live than to live for an idea that will die" - Steve Biko
Last week on Gamasutra was a good article on memory leak detection, and how to role your own tool:
"Monitoring Your PC's Memory Usage For Game Development"
While the title says it's for game development, I found that the meat of the article applies to any windows developer.
For example, this code has serious issues: extern string method_that_returns_string_object();
char *ptr;
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ptr = method_that_returns_string_object();
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And FWIW, I've used Purify on massive apps, and found huge problems that the developers didn't even know were there. On one project, they couldn't explain why their "perfect" app kept crashing, either. Worse for them, I had been hired as a consultant to fix their problems that they couldn't seem believe existed (HINT: your boss hired someone from the outside...), and after watching the team flail and spend literally almost a man-year trying to find one memory bug, I finally had enough of "advice giving" being ignored and got on their system, linked their app under Purify, ran it, and found the bug - a double delete of an object from two different threads. It all took me about fifteen minutes. I did that in front of their management. I made my point.
Purify (and like tools) are a great help. Not using them is like trying to build a house without power tools. Yeah, it can be done. But what would you think if hired a builder to make your house and his team showed up carrying hand saws? Oh, and you are paying that team to hand-saw all the lumber...
What would you think of that builder?
Yet, when a developer asks for tools like Purify, management often balks. Because 1) they're shortsighted, and 2) developers don't know how to use such tools.
Like I said - what would you think of a construction company where the workers don't know how to use modern power tools to help their productivity?
Well, you just put yourself in that category.
Yes, Purify is somewhat slower than running without Purify. But it's a lot faster than most other full-memory checking methods. If you're worried about speed, link against the Win32 debug libraries - they'll at least show problems with double free() calls, access of free()'d and deleted objects, etc. And without too much performance problems.
We are running many high speed financial message processing applications. A crash for any reason (including a leak) would be very costly for us.
.NET. Both sets of colleagues have had major performance problems caused directly by the garbage collectors kicking in and consuming vast CPU power while they did their thing. The result was a failure to process messages in a timely manner in our high speed environment. The solution in both languages was to use pools of reusable objects and never cause their reference counts to drop to 0. Thus they implemented the very same mechanism that we use in C++ and avoided the garbage collectors.
We pre-allocate pools of objects at startup and then re-use them. No other memory is allocated or freed while the process is running. Our pools of reusable objects are monitored very carefully as an object that isn't release back to its pool when the job is done is akin to a memory leak. Use of sentries to automatically release objects back to the pools when they fall out of scope is mandatory.
So my answer is to the problem is:
1. Use sentries (or some other mechanism) to guarantee memory is released.
2. Don't allocate except at startup.
3. No need for elaborate tools due to the above.
I'm sure that not all applications data usage would fit into this model, but it is surprising how many can.
We have seen some leaks in our applications. These were tracked down to STL internally leaking. They weren't generally very large and therefore we continue to live with them.
On the subject of garbage collectors, some of our colleagues use Java and
So don't think that a garbage collector is the solution. Perhaps in less demanding applications it is a potential answer.
Lastly, I strongly dislike anything from Rational. I find them overpriced unreliable bloatware (YMMV). Purify used to be good some time ago, but those days are long gone.
I echo what others have said above. You are a developer. You know your requirements. Build a simple tool to monitor and check your usage. For us it was managed pools of re-usable objects.
Memory checkers? GARBAGE COLLECTORS?! Have you no HONOR?!
We are KLINGON. We need no checkers. We need no garbage collectors. We need none of these weak HUMAN facilities. We write our CODE from the COMMAND LINE:
> COPY CON DECAPITATOR.EXE
[Alt+077] [ALT+090] . . .
FATMOUSE + YOU = FATMOUSE
Have a look at memory validator. I don't know if it supports 64 bit applications, but it has a great list of features and is the only decent memory validation tool I've ever seen on Windows.
Use a testing framework like Parasoft's CPP stuff http://www.parasoft.com/jsp/products/home.jsp?prod uct=CppTest
Australian running a company that does C# / C++ / Java / SQL / Python / Mathematica
GLIBC allows you to create hooks for the standard mem functions (malloc/realloc/free). Remember that g++ still calls these under new/delete so it works for C++ also.
One of our guys coded up a simple shared lib that can be loaded with LD_PRELOAD that sets simple hooks of printing memory locations for new/realloc/delete. He then wrote a perl script that kept track of these things and spit out anything that was malloc'ed and not realloc'ed or free'd.
I can't post it, because technically it's not my code it's my company's. But his shared lib code is just 300 lines long, and shouldn't be hard to duplicate. The perl log filter is even more straighforward. Each malloc gets saved. Each free removes the malloc. Each realloc removes the old malloc and adds a new one. Anything left over is a leak.
Override __malloc_initialize_hook with a pointer to your init_function. In your init_function, save the old functions at __malloc_hook __free_hook __memalign_hook and __realloc_hook and substitute your own. Now write your replacement functions, in it, do your logging and temporarily replce the old hooks and call the original functions, replace with your hook on the way out to get the next call. All of the hooks should be wrapped in a mutex to help re-entrancy problems.
It's not a full memory detector, just does leaks, but it's non-intrusive, requires no recompiles, and is the best way we have to leak detect our huge server long running code.