One problem I encountered when using the controlnet API

[wym19970515]

When continuously calling the controlnet API (/controlnet/txt2img), the following problems will occur：
I made the second API call before the first API call returned the result, viewing the process of image generation from the console, we can find that the first API call has ended but the result has not been returned in time. The result of the first API call will be delayed until the end of the second API call and returned together with the result of the second API call. And the picture returned by the API for the first time also does not meet expectations.
For example, I used this picture for the first time when I called the API:

And used this picture to make the second API call during the execution of the first API call:

The two results received at the same time after the second API execution are as follows:
Pictures and line drafts generated by the first API call:


Picture and line draft generated by the second API call:


It is obvious that the result of the first API call does not meet the expectation. It may be covered by the second API call.
This problem can also occur when calling the API three times at the same time. The results will be returned together after the three calls are completed, and the result pictures of the three calls are the same (not necessarily the one that should be generated in the last call to the API)

By the way, similar problems may occur when calling the original txt2img API and controlnet txt2img API at the same time.
I first called the original txt2img API, and then called the controlnet txt2img API before returning. The results of the two calls are returned together after the controlnet txt2img API is executed, and the two returned images are the same.