Thread local data and roots

[intrigus]

Hello,
my code looks like this:

static __thread Env env;

struct Env {
    nongcmember nogc;
    gcmember gc; 	
};

struct gcmember {
	void* operator new(std::size_t sz) {
		return GC_MALLOC(sz);
	}
};

void main(){
env.gc = new gcmember();
// doo stuff
// after some time env.gc seems to get collected 
// and another object gets allocated at the position 
}

I'm initializing the Env struct in my main method.
After some time I allocate the gcmember and store it in env.gc.
Then my application runs for quite some time and env.gc seems to get collected.

Now I have found one solution:

GC_add_roots(&env, &env + 1);

this works well, but I'd like to remove this root after the thread exited and the thread local variables are cleaned up.
So I looked at GC_CALL GC_remove_roots but in the docs it says:
"May be unimplemented on some platforms."

bdwgc/include/gc.h

Line 601 in 5937294

/* May be unimplemented on some platforms. */

Is there an easier way to use thread locals as roots?

[ivmai]

Thread-local objects are not scanned.
Add env thread-local values to a global collection (e.g. hashtable or double-linked list).
Like:

static __thread Env env;
static Env *envList; // points to the first env object (of the double-linked list) or nullptr

struct Env {
nongcmember nogc;
gcmember gc;
Env *prev; // points to previous and next env objects
Env *next;
};

PS. It's better to ask such questions on Stackoverflow - https://stackoverflow.com/questions/tagged/boehm-gc

[ivmai]

Or, a better way, I think, is to use GC_MALLOC_UNCOLLECTABLE:

struct Env {
nongcmember nogc;
gcmember gc;
};
static __thread Env *penv;
...
// init thread-local env:
penv = GC_NEW_UNCOLLECTABLE(Env);
...
// delete thread-local env:
GC_FREE(penv);