Optimize: Introduce multiple disk write for MPU

tosfs/core.py

@@ -116,7 +116,7 @@ def __init__(
         default_fill_cache: bool = True,
         default_cache_type: str = "readahead",
         multipart_staging_dirs: str = tempfile.mkdtemp(),
-        multipart_size: int = 4096,
+        multipart_size: int = 8 << 20,
         multipart_thread_pool_size: int = max(2, os.cpu_count() or 1),
         multipart_staging_buffer_size: int = 4096,
         multipart_threshold: int = 10485760,
@@ -169,15 +169,16 @@ def __init__(
             directory). Separate the staging dirs with comma if there are many
             staging dir paths.
         multipart_size : int, optional
-            The max byte size which will buffer the staging data in-memory before
-            flushing to the staging file. Decrease the random write in local staging
-            disk dramatically if writing plenty of small files. (default is 4096).
+            The multipart upload part size of the given object storage.
+            (default is 8MB).
         multipart_thread_pool_size : int, optional
-            The size of the thread pool for multipart uploads (default is
-            max(2, os.cpu_count()).
-        multipart_staging_buffer_size : int, optional
             The size of thread pool used for uploading multipart in parallel for the
-            given object storage. (default is 4096).
+            given object storage. (default is max(2, os.cpu_count()).
+        multipart_staging_buffer_size : int, optional
+            The max byte size which will buffer the staging data in-memory before
+            flushing to the staging file. It will decrease the random write in local
+            staging disk dramatically if writing plenty of small files.
+            (default is 4096).
         multipart_threshold : int, optional
             The threshold which control whether enable multipart upload during
             writing data to the given object storage, if the write data size is less
@@ -2043,6 +2044,7 @@ def __init__(
         self.multipart_threshold = fs.multipart_threshold
         self.executor = ThreadPoolExecutor(max_workers=self.thread_pool_size)
         self.staging_files: list[str] = []
+        self.staging_buffer: io.BytesIO = io.BytesIO()
 
         if "a" in mode and fs.exists(path):
             head = retryable_func_executor(
@@ -2089,7 +2091,7 @@ def _upload_chunk(self, final: bool = False) -> bool:
             self.autocommit
             and not self.append_block
             and final
-            and self.tell() < self.blocksize
+            and self.tell() < max(self.blocksize, self.multipart_threshold)
         ):
             # only happens when closing small file, use one-shot PUT
             pass
@@ -2133,12 +2135,27 @@ def _upload_multiple_chunks(self, bucket: str, key: str) -> None:
                 if not chunk:
                     break
 
-                staging_dir = next(self.staging_dirs)
-                with tempfile.NamedTemporaryFile(delete=False, dir=staging_dir) as tmp:
-                    tmp.write(chunk)
-                    self.staging_files.append(tmp.name)
+                self._write_to_staging_buffer(chunk)
+
+    def _write_to_staging_buffer(self, chunk: bytes) -> None:
+        self.staging_buffer.write(chunk)
+        if self.staging_buffer.tell() >= self.staging_buffer_size:
+            self._flush_staging_buffer()
+
+    def _flush_staging_buffer(self) -> None:
+        if self.staging_buffer.tell() == 0:
+            return
+
+        self.staging_buffer.seek(0)
+        staging_dir = next(self.staging_dirs)
+        with tempfile.NamedTemporaryFile(delete=False, dir=staging_dir) as tmp:
+            tmp.write(self.staging_buffer.read())
+            self.staging_files.append(tmp.name)
+
+        self.staging_buffer = io.BytesIO()
 
     def _upload_staged_files(self) -> None:
+        self._flush_staging_buffer()
         futures = []
         for i, staging_file in enumerate(self.staging_files):
             part_number = i + 1