32 lines
2.0 KiB
Plaintext
32 lines
2.0 KiB
Plaintext
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* GC issues you need to be careful about when hacking on the mono runtime.
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mono currently uses the Boehm garbage collection library. This is a conservative
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GC package: this means that the memory is searched for possible memory references
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to chunks allocated with the GC. Not all the memory is searched, but only the memory
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allocated with the GC itself (unless you use the 'atomic' variant of the allocation
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routines), the stack and global variables. Also, if the last reference to an object
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is stored in an area of themory that is not searched, the object may be freed resulting
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in memory corruption ind segfaults.
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In particular, memory allocated with system's malloc() is not searched, so you need to be
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careful NOT to store object references in memory allocated with malloc() (unless you are sure
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that the object reference will be live at the same time in some other area under the control
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of the GC (on the stack or in a global variable, for example). Since g_malloc()
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ultimately calls system malloc() the data structures in GLib are not safe to
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use to store object references.
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Occasionally, you'll need to store some object reference from C code: in this case,
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you must make sure that the store location is searched by the GC. You can safely
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use thread local storage areas, global variables, stack variables. If you need a more
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complicated data structure, you can use a hash table: MonoGHashTable.
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This hash table has the same interface as GHashTable from GLib, just stick the "mono_"
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prefix in function calls and the "Mono" prefix in the hash table type name.
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This hash table ensures that object references stored in it are tracked by the GC, as long
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as the pointer to the hash is tracked itself.
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Other data structures that are allocated with the GC and are safe to use to store pointers
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to GC-allocated memory, are MonoDomain (keeps track of many domain specfic objects)
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and MonoVTable (referenced by MonoDomain: keeps track of the static data of a type
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since that can hold references to objects).
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