Load Testing of Swing - Web integrated Application

I have to do load testing of Swing application.

Swing application has many documents. User can select any document and click on Stamp button. When Stamp button is clicked, in background , document bytearray and user details and one id is set to Web application

Web Application accepts these values and puts in application scope

After Swing application gets success response, it opens Browser with URL of Web Application and passes id In Browser, the document is opened with stamping tools. User can add stamp and save document.

I need to do load testing for this process. Which tool can be used and how to process it?