Question 1

How do I integrate bdwgc with my CMake-based C++ project?

Accepted Answer

Use the CMake build method: create a build directory, run 'cmake ..' and 'cmake --build .' from there, then link against the generated library. The README recommends CMake as the most cross-platform way and provides detailed steps in the cmake.md file.

Question 2

What's the performance overhead of bdwgc compared to manual malloc/free?

Accepted Answer

Performance varies by workload; the collector adds CPU overhead for scanning and collection pauses, which increase with heap size. However, it reduces manual memory errors, and incremental mode can minimize pauses for interactive apps.

Question 3

Does bdwgc work properly with C++ STL containers like vector or map?

Accepted Answer

Yes, but you must use gc_allocator.h to ensure STL subobjects are traced by the collector. Otherwise, pointers in STL structures allocated with system malloc may be missed, leading to premature collection.

Question 4

bdwgc vs other garbage collectors for C: which should I use?

Accepted Answer

bdwgc is unique for its conservative, non-invasive approach in C/C++; alternatives like Ravenbrook's MPS or language-specific GCs may offer more precision but require more integration effort. Choose bdwgc for ease of adoption in existing codebases.

Question 5

How to enable incremental garbage collection to reduce pauses?

Accepted Answer

Call GC_enable_incremental() in your code, but note it requires VM system support (e.g., /proc on Solaris) or manual dirty tracking via GC_end_stubborn_change, which adds complexity and platform dependencies.

Question 6

Why is my bdwgc program still leaking memory with FIND_LEAK enabled?

Accepted Answer

FIND_LEAK mode reports inaccessible objects, but leaks might persist if pointers are hidden in unsupported areas like thread-local storage or dynamic libraries. Ensure all roots are registered and use GC_debug_malloc for detailed allocation logs.

Question 7

Is bdwgc suitable for game development where frame rate is critical?

Accepted Answer

Generally not ideal due to unpredictable collection pauses; real-time games need consistent performance. However, if used, enable incremental collection and allocate large objects with GC_malloc_ignore_off_page to mitigate pauses.

Boehm GC

What is Boehm GC?

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