I am handling an upload using fileUpload() inside a coldbox application. It was initially in a model, where I was unzipping the uploaded file, importing CSV files then processing the database using array.each with parallel = true in several locations. Every time the loops ran, the server duplicates the tmp-xxx.upload file in the \WEB-INF\lucee-web\temp folder. This only happens when the parallel = true flag is passed.
It doesn't matter whether the fileUpload() function is in the model or the handler. It duplicated the 10MB zip folder so many times it ate 126GB of hard drive space and crashed the database in under 5 minutes.