Can Boehm\'s Conservative Garbage Collector Be Integrated with the C Standard Library for Multi-threaded Applications?

Integrating Conservative Garbage Collection with the C Standard Library

Question:

In a multi-threaded C application, can Boehm's conservative garbage collector (GC) be effectively utilized in conjunction with the C standard library? Specifically, how should operator ::new and the allocators provided by std::vector and std::string be handled?

Answer:

1. Redefining operator ::new:

Redefining ::operator new with Boehm's GC is not necessary. By utilizing Boehm's GC properly, it is possible to avoid explicitly redefining ::operator new.

2. Allocators for Standard Library Containers:

std::vector:

• Use std::vector with an explicit allocator parameter set to Boehm's gc_allocator. This ensures that both the internal data structure and individual elements are GC-allocated.

std::string:

• To GC-allocate the internal character array, use your own custom string implementation derived from std::basic_string and employ gc_allocator.
• There is no easy way to force GC_malloc_atomic allocation for the character array in the standard implementation.

Example:

The following code demonstrates a custom implementation of a GC-allocated vector:

<code class="cpp">#include <gc/gc_cpp.h>
#include <gc/gc_allocator.h>
#include <vector>

class Myvec {
  std::vector<int, gc_allocator<int>> _vec;
public:
  Myvec(size_t sz = 0) : _vec(sz) {}
  // ... (rest of class implementation)
};</code>

3. Compatibility with g :

Yes, it is possible to use Boehm GC with an application compiled by g . Follow the above guidelines to integrate GC with the standard library effectively.

Addendum (January 2017):

• Check the proposals n2670 and and garbage collection support for potential future enhancements in garbage collection capabilities of C .

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