the foreground uses ajax to request the backend. A simple operation, such as submitting the form, calls another ajax request to refresh the list after the form is successfully returned. After receiving the form data, my backend saves the form data into the database, and then returns the success. After the code returned by reponse, continue to process the business logic, so that when the backend continues to process the business logic, the foreground has been successfully returned. Then the foreground continues to initiate a request to refresh the form, but finds that the background must wait until the previous request to submit the form has processed all the business code before responding to the request to refresh the form. It feels like a thread is processing the request serially. As far as I understand it, a request request should take a new thread from the thread pool to process the request to the corresponding whole process, and each request should be independent. Why is there such a situation in which a single thread processes multiple requests at the same time? Is it the reason why it was launched on the same page? Because as long as you open another page, there will be no problem, and the blocking of the current page will not affect another page