mono_mutex_lock (&threadpool->active_threads_lock);
for (i = 0; i < threadpool->working_threads->len; ++i) {
thread = g_ptr_array_index (threadpool->working_threads, i);
mono_mutex_lock (&threadpool->active_threads_lock);
for (i = 0; i < threadpool->working_threads->len; ++i) {
thread = g_ptr_array_index (threadpool->working_threads, i);