updated default block size

CHANGELOG.md

@@ -7,6 +7,9 @@ Unreleased
 - Fix issue where ``AzureBlobFile`` did not respect ``location_mode`` parameter
   from parent ``AzureBlobFileSystem`` when using SAS credentials and connecting to
   new SDK clients.
+- The block size is now used for partitioned uploads. Previously, 1 GiB was used for each uploaded block irrespective of the block size  
+- Updated default block size to be 50 MiB. Set `blocksize` for `AzureBlobFileSystem` or `block_size` when opening `AzureBlobFile` to revert back to 5 MiB default. 
+- `AzureBlobFile` now inherits the block size from `AzureBlobFileSystem` when fs.open() is called and a block_size is not passed in.
 
 
 2024.12.0

adlfs/spec.py

@@ -69,7 +69,7 @@
     "is_current_version",
 ]
 _ROOT_PATH = "/"
-_DEFAULT_BLOCK_SIZE = 4 * 1024 * 1024
+_DEFAULT_BLOCK_SIZE = 50 * 2**20
 
 _SOCKET_TIMEOUT_DEFAULT = object()
 
@@ -177,8 +177,7 @@ class AzureBlobFileSystem(AsyncFileSystem):
         The credentials with which to authenticate.  Optional if the account URL already has a SAS token.
         Can include an instance of TokenCredential class from azure.identity.aio.
     blocksize: int
-        The block size to use for download/upload operations. Defaults to hardcoded value of
-        ``BlockBlobService.MAX_BLOCK_SIZE``
+        The block size to use for download/upload operations. Defaults to 50 MiB
     client_id: str
         Client ID to use when authenticating using an AD Service Principal client/secret.
     client_secret: str
@@ -1863,7 +1862,8 @@ def _open(
             What mode to open the file in - defaults to "rb"
 
         block_size: int
-            Size per block for multi-part downloads.
+            Size per block for multi-part uploads and downloads. This overrides the block_size parameter
+            and if not provided, defaults to the filesystem blocksize.
 
         autocommit: bool
             Whether or not to write to the destination directly
@@ -1879,6 +1879,8 @@ def _open(
             is versioning aware and blob versioning is enabled on the releveant container.
         """
         logger.debug(f"_open:  {path}")
+        if block_size is None:
+            block_size = self.blocksize
         if not self.version_aware and version_id:
             raise ValueError(
                 "version_id cannot be specified if the filesystem "
@@ -1901,7 +1903,7 @@ def _open(
 class AzureBlobFile(AbstractBufferedFile):
     """File-like operations on Azure Blobs"""
 
-    DEFAULT_BLOCK_SIZE = 5 * 2**20
+    DEFAULT_BLOCK_SIZE = _DEFAULT_BLOCK_SIZE
 
     def __init__(
         self,
@@ -2146,11 +2148,11 @@ async def _async_initiate_upload(self, **kwargs):
 
     _initiate_upload = sync_wrapper(_async_initiate_upload)
 
-    def _get_chunks(self, data, chunk_size=1024**3):  # Keeping the chunk size as 1 GB
+    def _get_chunks(self, data):
         start = 0
         length = len(data)
         while start < length:
-            end = min(start + chunk_size, length)
+            end = min(start + self.blocksize, length)
             yield data[start:end]
             start = end
 

adlfs/tests/test_spec.py

@@ -1,4 +1,5 @@
 import datetime
+import math
 import os
 import tempfile
 from unittest import mock
@@ -2045,3 +2046,88 @@ def test_open_file_x(storage: azure.storage.blob.BlobServiceClient, tmpdir):
         with fs.open("data/afile", "xb") as f:
             pass
     assert fs.cat_file("data/afile") == b"data"
+
+
+def test_uses_block_size_for_partitioned_uploads(storage, mocker):
+    from azure.storage.blob.aio import BlobClient
+
+    blocksize = 5 * 2**20
+    fs = AzureBlobFileSystem(
+        account_name=storage.account_name,
+        connection_string=CONN_STR,
+        blocksize=blocksize,
+    )
+
+    content = b"1" * (blocksize * 4 + 1)
+    with fs.open("data/root/a/file.txt", "wb") as f:
+        mock_stage_block = mocker.patch.object(BlobClient, "stage_block")
+        mock_commit_block_list = mocker.patch.object(BlobClient, "commit_block_list")
+        f.write(content)
+        expected_blocks = math.ceil(len(content) / blocksize)
+        actual_blocks = mock_stage_block.call_count
+        assert actual_blocks == expected_blocks
+        block_lengths = [
+            call.kwargs["length"] for call in mock_stage_block.call_args_list
+        ]
+        assert sum(block_lengths) == len(content)
+
+    assert len(mock_commit_block_list.call_args.kwargs["block_list"]) == expected_blocks
+
+
+@pytest.mark.parametrize(
+    "filesystem_blocksize, file_blocksize, expected_blocksize, expected_filesystem_blocksize",
+    [
+        (None, None, 50 * 2**20, None),
+        (7 * 2**20, None, 7 * 2**20, 7 * 2**20),
+        (None, 5 * 2**20, 5 * 2**20, None),
+        (40 * 2**20, 7 * 2**20, 7 * 2**20, 40 * 2**20),
+    ],
+)
+def test_block_size(
+    storage,
+    filesystem_blocksize,
+    file_blocksize,
+    expected_blocksize,
+    expected_filesystem_blocksize,
+):
+    fs = AzureBlobFileSystem(
+        account_name=storage.account_name,
+        connection_string=CONN_STR,
+        blocksize=filesystem_blocksize,
+    )
+
+    with fs.open("data/root/a/file.txt", "wb", block_size=file_blocksize) as f:
+        assert f.blocksize == expected_blocksize
+        assert fs.blocksize == expected_filesystem_blocksize
+
+
+@pytest.mark.parametrize(
+    "file_blocksize, expected_blocksize",
+    [
+        (None, 50 * 2**20),
+        (8 * 2**20, 8 * 2**20),
+    ],
+)
+def test_blocksize_from_blobfile(storage, file_blocksize, expected_blocksize):
+    fs = AzureBlobFileSystem(
+        account_name=storage.account_name, connection_string=CONN_STR
+    )
+    f = AzureBlobFile(
+        fs,
+        "data/root/a/file.txt",
+        block_size=file_blocksize,
+    )
+    assert f.blocksize == expected_blocksize
+
+
+def test_blobfile_default_blocksize(storage):
+    fs = AzureBlobFileSystem(
+        account_name=storage.account_name,
+        connection_string=CONN_STR,
+        blocksize=20 * 2**20,
+    )
+    f = AzureBlobFile(
+        fs,
+        "data/root/a/file.txt",
+    )
+    assert f.blocksize == 50 * 2**20