s3fs is significantly slower than boto3 for large file uploads

[b23g5r42i]

I've noticed that while uploading large files (greater than 1GB), s3fs.write() performs around three times slower than the boto3.upload_file() API.

Is this slower performance expected when using s3fs, and are there any configurations or optimizations that could improve its upload speed?

import boto3
import time

# MinIO server setup
endpoint_url = 'http://localhost:9000'
access_key = ''
secret_key = ''
bucket_name = 'test-bucket'
file_path = 'large_file.bin'
key = 'uploaded_file.bin'

file_size_mb = 4096
with open(file_path, 'wb') as f:
    f.write(os.urandom(file_size_mb * 1024 * 1024))
print(f"Created a {file_size_mb}MB test file.")

fs = s3fs.S3FileSystem(client_kwargs={'endpoint_url': endpoint_url}, key=access_key, secret=secret_key)

s3 = boto3.client('s3', endpoint_url=endpoint_url, aws_access_key_id=access_key, aws_secret_access_key=secret_key)

start_time = time.time()
with fs.open(f'{bucket_name}/{key}', 'wb') as f:
    f.write(open(file_path, 'rb').read())
print(f"s3fs upload time: {time.time() - start_time} seconds")

start_time = time.time()
s3.upload_file(Filename=file_path, Bucket=bucket_name, Key=key)
print(f"boto3 upload time: {time.time() - start_time} seconds")

[martindurant]

In file-like mode (using open()), you are limited by the blocking nature of the API. s3fs will upload one block_size chunk at a time, serially. This is configurable block_size= and only 5MB by default, optimised for minimum memory use. We have discussed greatly increasing the value, but you can do this yourself in the call.

The non-file upload-from-disk method is

fs.put_file(file_path)

and already has a larger 50MB block (called chunksize in the call). These calls are also make the calls concurrently. This is what you want.

[b23g5r42i]

@martindurant Thanks for the reply! Increasing the block_size can indeed boost speed by up to 50% in my tests, but it's still about twice as slow as boto3, which I believe benefits from better concurrency handling.

The put_file() method looks useful, but it seems to work only with file paths. Is there a version modified with fsspec that could, for example, support pickle.dump() directly? My main goal is to unify I/O operations with upath + fsspec, including S3

[martindurant]

Would you care to test with #901

It's worth pointing out that s3transfer and maybe boto3 use threads and/or processes for parallelism, which matters in low0latency situations where the CPU time for stream compression might be significant. s3fs is single-threaded.

[martindurant]

it seems to work only with file paths

I was trying to match your code of writing the whole contents of a file. To push bytes from memory in one go:

fs.pipe(path, value)

(where you could have value = pickle.dumps(..)).

I also started #901 for you to speed test.

[b23g5r42i]

Hi, with pickle.dumps(), it calls fsspec's write() interface, so I think we only need to make change to line to enable the new block size. Meanwhile, in my testing I find max_concurrency has no impact to performance...

Here is my testing code:

with fs.open(f'{bucket_name}/{key}', 'wb', block_size=BLOCK_SIZE, max_concurrency=CONCURRENCY) as f:
    f.write(open(file_path, 'rb').read())

With an 1GB object, default block size 5MB gives me 40MB/s while 50MB gives 70MB/s, and 500MB gives 90MB/s. But boto3 gives 160MB/s. Changing max_concurrency from 1 to 10 has not impact to the speed at all.