`Aws::S3::MultipartFileUploader` leaks file descriptors on error

[ClearlyClaire]

Describe the bug

After investigating an issue that was reported out against our project (mastodon/mastodon#39863), I am under the impression that multipart file uploads as currently implemented in aws-sdk-s3 are leaking file descriptors when hitting upload errors.

Regression Issue

• Select this option if this issue appears to be a regression.

Expected Behavior

MultipartFileUploader always closes files it opens.

Current Behavior

MultipartFileUploader seems to only close opened file descriptors for part uploads on success.

Reproduction Steps

Upload a file using Multipart File Upload with very low timeouts so that uploading fails and leaks file descriptors.

Possible Solution

p[:body].close should probably be called in the ensure or rescue block (see monkey-patch that seems to solve the issue: mastodon/mastodon#39863 (comment))

Additional Information/Context

aws-sdk-ruby/gems/aws-sdk-s3/lib/aws-sdk-s3/multipart_file_uploader.rb

Lines 153 to 167 in 53d6f17

	@executor.post(part) do |p|
	Thread.current[:net_http_override_body_stream_chunk] = @http_chunk_size if @http_chunk_size
	update_progress(progress, p)
	resp = @client.upload_part(p)
	p[:body].close
	completed_part = { etag: resp.etag, part_number: p[:part_number] }
	apply_part_checksum(resp, completed_part)
	completed.push(completed_part)
	rescue StandardError => e
	abort_upload = true
	errors << e
	ensure
	Thread.current[:net_http_override_body_stream_chunk] = nil if @http_chunk_size
	completion_queue << :done
	end

Gem name ('aws-sdk', 'aws-sdk-resources' or service gems like 'aws-sdk-s3') and its version

aws-sdk-s3 1.225.1

Environment details (Version of Ruby, OS environment)

ruby 4.0.5 (2026-05-20 revision 64336ffd0e) +PRISM [x86_64-linux]

[jterapin]

Hi! Thank you for reporting. We'll take a look and follow up if we have any questions.

[jterapin]

I've opened a PR with the fix, which is now under review by our team. Once it's approved and released, I'll follow up here with the aws-sdk-s3 version that includes it.

Thanks again for the report and the suggested fix!

[github-actions]

This issue is now closed. Comments on closed issues are hard for our team to see.
If you need more assistance, please open a new issue that references this one.

[jterapin]

Hi! Fix is released: https://rubygems.org/gems/aws-sdk-s3/versions/1.228.1

Let me know if you have any questions. Thanks!