Worked on the rclone/rclone repository to enhance the reliability of large file uploads in the pCloud backend. Addressed a concurrency issue by implementing atomic handling of clients and file descriptors, ensuring that each upload chunk and its retries operated with a dedicated TCP connection. This approach reduced upload failures and improved data integrity, particularly under high-concurrency scenarios. The solution was validated for thread safety and robustness, directly resolving a long-standing bug affecting multi-threaded uploads. Leveraged Go for backend development, focusing on API integration, cloud storage integration, and error handling to deliver a targeted fix that improved throughput and user experience.