Django - Handling several file upload requests at a time?
What should be the upper limit?

That depends on your hardware such as quantity of core in your server

Is there any other solution that I can use in this scenario?

Consider using Celery/rabbitMQ. Celery could be used to process asynchronously file or upload to S3 and notify the events to rabbitMQ
I am developing a django application which handles lots of file uploads from multiple clients periodically. Each file is around 1 to 10 megabytes.
Since uploads are thread blocking I can only serve a number of requests equivalent to the number of uwsgi workers/processes (4 in my case).
What should I do to increase throughput?
Is it advisable to increase number of processes/workers in uwsgi? 
What should be the upper limit? 
Is there any other solution that I can use in this scenario?
Stack: django+uwsgi+nginx running on amazon ec2 and s3 buckets used for storing zip files.