Function stress

3rd/mimalloc-2.0.9/test/test-stress.c:125–178

static void stress(intptr_t tid) {
  //bench_start_thread();
  uintptr_t r = ((tid + 1) * 43); // rand();
  const size_t max_item_shift = 5; // 128
  const size_t max_item_retained_shift = max_item_shift + 2;
  size_t allocs = 100 * ((size_t)SCALE) * (tid % 8 + 1); // some threads do more
  size_t retain = allocs / 2;
  void** data = NULL;
  size_t data_size = 0;
  size_t data_top = 0;
  void** retained = (void**)custom_calloc(retain,sizeof(void*));
  size_t retain_top = 0;

  while (allocs > 0 || retain > 0) {
    if (retain == 0 || (chance(50, &r) && allocs > 0)) {
      // 50%+ alloc
      allocs--;
      if (data_top >= data_size) {
        data_size += 100000;
        data = (void**)custom_realloc(data, data_size * sizeof(void*));
      }
      data[data_top++] = alloc_items(1ULL << (pick(&r) % max_item_shift), &r);
    }
    else {
      // 25% retain
      retained[retain_top++] = alloc_items( 1ULL << (pick(&r) % max_item_retained_shift), &r);
      retain--;
    }
    if (chance(66, &r) && data_top > 0) {
      // 66% free previous alloc
      size_t idx = pick(&r) % data_top;
      free_items(data[idx]);
      data[idx] = NULL;
    }
    if (chance(25, &r) && data_top > 0) {
      // 25% exchange a local pointer with the (shared) transfer buffer.
      size_t data_idx = pick(&r) % data_top;
      size_t transfer_idx = pick(&r) % TRANSFERS;
      void* p = data[data_idx];
      void* q = atomic_exchange_ptr(&transfer[transfer_idx], p);
      data[data_idx] = q;
    }
  }
  // free everything that is left
  for (size_t i = 0; i < retain_top; i++) {
    free_items(retained[i]);
  }
  for (size_t i = 0; i < data_top; i++) {
    free_items(data[i]);
  }
  custom_free(retained);
  custom_free(data);
  //bench_end_thread();
}

static void run_os_threads(size_t nthreads, void (*entry)(intptr_t tid));