Linux上的多线程C ++应用程序中的内存泄漏

Question

We have a big multi-threaded C++ application running on Linux. We see that occupied by the application memory grows fast and believe there are some leaks. We have tried every tool we have (valgrind, DynLeak, Purify) but did not find anything. Since this application can run on Windows, we have also tried Bounds Checker. Did not help, too.

We need a new tool that can help. I've looked at Google Perfomrance Tools, MMGR by Paul Nettle, MemCheck Deluxe. None of them impressed me.

Is there anywhere a good tool for this task?

Answer 1

The definition of a memory leak in C/C++ is very specific: it is memory that has been allocated and then the pointer was overwritten or otherwise lost. Valgrind generally detects such cases out of the box, but things are not always that simple.

• Your application could very well be still using that memory. In that case you might have what a Java programmer would consider a leak, eg entering data in a structure and rarely (or never) removing entries.

• You might be measuring the memory usage of your memory incorrectly. On Linux memory usage measurements are not as straight-forward as they seem. How have you measured your memory usage?

• You should consider using the application hooks (Valgrind calls them client requests ) of whatever memory analysis tool your are using, to avoid the issue with reports only being issued at program termination. Using those hooks might help you pin-point the location of your leak.

• You should try using a heap profiler, such as massif from Valgrind, to look for memory allocation locations with inordinate amounts of allocated memory.

• Make sure you are not using a custom allocator or garbage collector in your application. As far as I know, no memory analysis tool will work with a custom allocator without user interference .

• If your memory leak is massive enough to be detectable within an acceptable amount of application run-time, you could try a binary search of old revisions through your version control system to identify the commit that introduced the problem. At least Mercurial and Git offer built-in support for this task.

Answer 2

如果“没有帮助”你的意思是它没有报告内存泄漏，很可能你没有它，只是使用越来越多的内存，仍然被指针引用，可以删除。

Answer 3

To help you debug the problem, perhaps in your logging, you should also write memory size, number of objects (their type) and a few other stats which are useful to you. At least until you become more familiar with the tools you mentioned.