nw = a->num_writers;
a->writer_nums = para_realloc(a->writer_nums, (nw + 1) * sizeof(int));
a->writer_conf = para_realloc(a->writer_conf, (nw + 1) * sizeof(void *));
a->writer_nums[nw] = writer_num;
a->writer_conf[nw] = wconf;
nw = a->num_writers;
a->writer_nums = para_realloc(a->writer_nums, (nw + 1) * sizeof(int));
a->writer_conf = para_realloc(a->writer_conf, (nw + 1) * sizeof(void *));
a->writer_nums[nw] = writer_num;
a->writer_conf[nw] = wconf;