[Frontend] Optionally remove memory buffer used for uploading to URLs in run_batch (#12927)

Signed-off-by: Pooya Davoodi <pooya.davoodi@parasail.io>

vllm/entrypoints/openai/run_batch.py

 # SPDX-License-Identifier: Apache-2.0
 
 import asyncio
+import tempfile
 from http import HTTPStatus
 from io import StringIO
 from typing import Awaitable, Callable, List, Optional
@@ -51,6 +52,13 @@ def parse_args():
         help="The path or url to a single output file. Currently supports "
         "local file paths, or web (http or https) urls. If a URL is specified,"
         " the file should be available via HTTP PUT.")
+    parser.add_argument(
+        "--output-tmp-dir",
+        type=str,
+        default=None,
+        help="The directory to store the output file before uploading it "
+        "to the output URL.",
+    )
     parser.add_argument("--response-role",
                         type=nullable_str,
                         default="assistant",
@@ -134,17 +142,107 @@ async def read_file(path_or_url: str) -> str:
             return f.read()
 
 
-async def write_file(path_or_url: str, data: str) -> None:
+async def write_local_file(output_path: str,
+                           batch_outputs: List[BatchRequestOutput]) -> None:
+    """
+    Write the responses to a local file.
+    output_path: The path to write the responses to.
+    batch_outputs: The list of batch outputs to write.
+    """
+    # We should make this async, but as long as run_batch runs as a
+    # standalone program, blocking the event loop won't effect performance.
+    with open(output_path, "w", encoding="utf-8") as f:
+        for o in batch_outputs:
+            print(o.model_dump_json(), file=f)
+
+
+async def upload_data(output_url: str, data_or_file: str,
+                      from_file: bool) -> None:
+    """
+    Upload a local file to a URL.
+    output_url: The URL to upload the file to.
+    data_or_file: Either the data to upload or the path to the file to upload.
+    from_file: If True, data_or_file is the path to the file to upload.
+    """
+    # Timeout is a common issue when uploading large files.
+    # We retry max_retries times before giving up.
+    max_retries = 5
+    # Number of seconds to wait before retrying.
+    delay = 5
+
+    for attempt in range(1, max_retries + 1):
+        try:
+            # We increase the timeout to 1000 seconds to allow
+            # for large files (default is 300).
+            async with aiohttp.ClientSession(timeout=aiohttp.ClientTimeout(
+                    total=1000)) as session:
+                if from_file:
+                    with open(data_or_file, "rb") as file:
+                        async with session.put(output_url,
+                                               data=file) as response:
+                            if response.status != 200:
+                                raise Exception(f"Failed to upload file.\n"
+                                                f"Status: {response.status}\n"
+                                                f"Response: {response.text()}")
+                else:
+                    async with session.put(output_url,
+                                           data=data_or_file) as response:
+                        if response.status != 200:
+                            raise Exception(f"Failed to upload data.\n"
+                                            f"Status: {response.status}\n"
+                                            f"Response: {response.text()}")
+
+        except Exception as e:
+            if attempt < max_retries:
+                logger.error(
+                    f"Failed to upload data (attempt {attempt}). "
+                    f"Error message: {str(e)}.\nRetrying in {delay} seconds..."
+                )
+                await asyncio.sleep(delay)
+            else:
+                raise Exception(f"Failed to upload data (attempt {attempt}). "
+                                f"Error message: {str(e)}.") from e
+
+
+async def write_file(path_or_url: str, batch_outputs: List[BatchRequestOutput],
+                     output_tmp_dir: str) -> None:
+    """
+    Write batch_outputs to a file or upload to a URL.
+    path_or_url: The path or URL to write batch_outputs to.
+    batch_outputs: The list of batch outputs to write.
+    output_tmp_dir: The directory to store the output file before uploading it
+    to the output URL.
+    """
     if path_or_url.startswith("http://") or path_or_url.startswith("https://"):
-        async with aiohttp.ClientSession() as session, \
-                   session.put(path_or_url, data=data.encode("utf-8")):
-            pass
+        if output_tmp_dir is None:
+            logger.info("Writing outputs to memory buffer")
+            output_buffer = StringIO()
+            for o in batch_outputs:
+                print(o.model_dump_json(), file=output_buffer)
+            output_buffer.seek(0)
+            logger.info("Uploading outputs to %s", path_or_url)
+            await upload_data(
+                path_or_url,
+                output_buffer.read().strip().encode("utf-8"),
+                from_file=False,
+            )
+        else:
+            # Write responses to a temporary file and then upload it to the URL.
+            with tempfile.NamedTemporaryFile(
+                    mode="w",
+                    encoding="utf-8",
+                    dir=output_tmp_dir,
+                    prefix="tmp_batch_output_",
+                    suffix=".jsonl",
+            ) as f:
+                logger.info("Writing outputs to temporary local file %s",
+                            f.name)
+                await write_local_file(f.name, batch_outputs)
+                logger.info("Uploading outputs to %s", path_or_url)
+                await upload_data(path_or_url, f.name, from_file=True)
     else:
-        # We should make this async, but as long as this is always run as a
-        # standalone program, blocking the event loop won't effect performance
-        # in this particular case.
-        with open(path_or_url, "w", encoding="utf-8") as f:
-            f.write(data)
+        logger.info("Writing outputs to local file %s", path_or_url)
+        await write_local_file(path_or_url, batch_outputs)
 
 
 def make_error_request_output(request: BatchRequestInput,
@@ -317,12 +415,7 @@ async def main(args):
     with tracker.pbar():
         responses = await asyncio.gather(*response_futures)
 
-    output_buffer = StringIO()
-    for response in responses:
-        print(response.model_dump_json(), file=output_buffer)
-
-    output_buffer.seek(0)
-    await write_file(args.output_file, output_buffer.read().strip())
+    await write_file(args.output_file, responses, args.output_tmp_dir)
 
 
 if __name__ == "__main__":