[BUG]Django Template error: Too many file is open

**Describe the bug**
When I use the html template `django` and set it reload to `true`
Then I flush my web page, many times
It will response http code 500, and tell me `Too many file is open`

**To Reproduce**
Steps to reproduce the behavior:
1. download my project from , the commit hash is`507b6b49427c2be46743902cf5bc041bf06f5f2d`
2. complete it
3. change the config file at `config/config.json`, set debug to `true`
4. run server
5. flush the web page, many times
6. the page will response 500 and tell you `Too many file is open`

**Expected behavior**
The web will running safe

**Desktop (please complete the following information):**
- OS: Mac

**iris.Version**
- v12.2.0-alpha