private synchronized void initBuckets() {
    final SparseIntArray bucketSizes = mPoolParams.bucketSizes;

    // create the buckets
    if (bucketSizes != null) {
      fillBuckets(bucketSizes);
      mAllowNewBuckets = false;
    } else {
      mAllowNewBuckets = true;
    }
  }
Initialize the list of buckets. Get the bucket sizes (and bucket lengths) from the bucket sizes
provider
imagepipeline/src/main/java/com/facebook/imagepipeline/memory/BasePool.java