Enable Multithreading on msgpack Chunking in BulkImportWriter (#142)

* Enable multithreading on msgpack chunking

* remove redundant parameter from different PR

* Slight refactor

Author: DavidLandup0

pytd/writer.py

@@ -452,19 +452,29 @@ def write_dataframe(
                 _replace_pd_na(dataframe)
                 num_rows = len(dataframe)
                 # chunk number of records should not exceed 200 to avoid OSError
-                _chunk_record_size = max(chunk_record_size, num_rows//200)
+                _chunk_record_size = max(chunk_record_size, num_rows // 200)
                 try:
-                    for start in range(0, num_rows, _chunk_record_size):
-                        records = dataframe.iloc[
-                            start : start + _chunk_record_size
-                        ].to_dict(orient="records")
-                        fp = tempfile.NamedTemporaryFile(
-                            suffix=".msgpack.gz", delete=False
-                        )
-                        fp = self._write_msgpack_stream(records, fp)
-                        fps.append(fp)
-                        stack.callback(os.unlink, fp.name)
-                        stack.callback(fp.close)
+                    with ThreadPoolExecutor(max_workers=max_workers) as executor:
+                        futures = []
+                        for start in range(0, num_rows, _chunk_record_size):
+                            records = dataframe.iloc[
+                                start : start + _chunk_record_size
+                            ].to_dict(orient="records")
+                            fp = tempfile.NamedTemporaryFile(
+                                suffix=".msgpack.gz", delete=False
+                            )
+                            futures.append(
+                                (
+                                    start,
+                                    executor.submit(
+                                        self._write_msgpack_stream, records, fp
+                                    ),
+                                )
+                            )
+                            stack.callback(os.unlink, fp.name)
+                            stack.callback(fp.close)
+                        for start, future in sorted(futures):
+                            fps.append(future.result())
                 except OSError as e:
                     raise RuntimeError(
                         "failed to create a temporary file. "