How to concurrently list_objects in S3 bucket with aioboto3

Question

I want to find all the unique paths in an S3 bucket, I want all the paths just before the file level. The depth of the directories can vary so not all files are found in the same depth for example I might have these files :

data/subdir1/subdir2/file.csv
data/subdir1/subdir3/subdir4/subdir5/file2.csv
data/subdir6/subdir7/subdir8/file3.csv

and I want these directories:

data/subdir1/subdir2/
data/subdir1/subdir3/subdir4/subdir5/
data/subdir6/subdir7/subdir8/

I am using the code below to get them. I use an async for loop with paginator cause I though they would be processed concurrently but I am not sure they are. It seems very slow so I think they are still done in series:

    subfolders = set()
    current_path = None

    paginator = self.s3_client.get_paginator("list_objects")

    async for result in paginator.paginate(Bucket=bucket, Prefix=prefix):
        for file in result.get("Contents", []):
            current_path = os.path.dirname(file.get("Key"))
            if current_path not in subfolders:
                subfolders.add(current_path)
            print(f"Part Done")

    return subfolders

My s3_client is an aioboto3 client.

Is there a way to speed up the process of finding and saving the directories ?

Note: I realized that this method does not bring me all the results only those from the current paginator can I get the next paginator asynchronously?

Answer 1

I didn't find a way to parallelize on the returned objects BUT I parallelized using many initial prefixes like this:

    subfolders = set()
    prefix_tasks = [get_subfolders(bucket, prefix) for prefix in prefixes]
    try:

        for prefix_future in asyncio.as_completed(prefix_tasks):
            prefix_subfolders = await prefix_future
            subfolders.update(prefix_subfolders)

    except KeyError as exc:
        print(f"Scanning origin bucket failed due to: {exc}")
        raise exc

where my get_subfolders function is:

async def get_subfolders(self, bucket: str, prefix: str) -> List[str]:

    subfolders = set()

    result = await self.s3_client.list_objects_v2(Bucket=bucket, Prefix=prefix)
    objects = result.get("Contents")
    subfolders.update(await self._get_paths_by_depth(objects=objects, depth=4))

    # Use next continuation token for pagination for truncated results.
    while result["IsTruncated"]:
        result = await self.s3_client.list_objects_v2(
            Bucket=bucket,
            Prefix=prefix,
            ContinuationToken=result["NextContinuationToken"],
        )
        objects = result.get("Contents")
        subfolders.update(await self._get_paths_by_depth(objects=objects, depth=4))

    return subfolders

and my get_paths_by_depth() function is :

    async def get_paths_by_depth(self, objects: dict, depth: int) -> Set[str]:
    subfolders = set()
    current_path = None
    try:
        # Get only paths with depth equal to 'depth' levels
        for bucket_object in objects:
            current_path = os.path.dirname(bucket_object["Key"])
            if current_path.count("/") == depth:
                subfolders.add(current_path)

    except Exception as exc:
        print(f"Getting subfolders failed due to error: {exc}")
        raise exc

    return subfolders

Answer 2

I propose to try
paginator = self.s3_client.get_paginator("list_objects_v2")
(note _v2) fix for multiple pages.