Finalize mutex prior to sweeping

gc.c

@@ -573,6 +573,15 @@ size_t gc_sweep(gc_heap *h, size_t *sum_freed_ptr)
         fprintf(stderr, "sweep is freeing unmarked obj: %p with tag %ld\n", p, type_of(p));
 #endif
         mark(p) = gc_color_blue; // Needed?
+        if (type_of(p) == mutex_tag) {
+#if GC_DEBUG_VERBOSE
+          fprintf(stderr, "pthread_mutex_destroy from sweep\n");
+#endif
+          if (pthread_mutex_destroy(&(((mutex)p)->lock)) != 0) {
+            fprintf(stderr, "Error destroying mutex\n");
+            exit(1);
+          }
+        }
         // free p
         heap_freed += size;
         if (((((char *)q) + q->size) == (char *)p) && (q != h->free_list)) {

test.scm

@@ -14,6 +14,7 @@
 (define tmp2 (make-mutex))
 (mutex-lock! tmp2)
 (mutex-unlock! tmp2)
+(set! tmp2 #f)
 
 ;; A program to prove if cooperation is working, or if it
 ;; is blocked by another thread. The (read) causes the main