The relationship between directive "scgi_busy_buffers_size" and other two directives is not recorded clearly.
|Reported by:||Owned by:|
|uname -a:||Linux xlarge 4.15.0-72-generic #81-Ubuntu SMP Tue Nov 26 12:20:02 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux|
nginx version: nginx/1.18.0
built by gcc 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)
configure arguments: --prefix=/usr/local/nginx --with-pcre=/root/Downloads/pcre-8.43
In the document of directive "scgi_busy_buffers_size", it says that "By default, size is limited by the size of two buffers set by the scgi_buffer_size and scgi_buffers directives". Indeed, based on the handling logic in src/http/modules/ngx_http_scgi_module.c, the value of "scgi_busy_buffers_size" must be equal or greater than the maximum of the value of "scgi_buffer_size" and "scgi_buffers" size. So it is recommended to add this information in the doc of "scgi_busy_buffers_size"(https://nginx.org/en/docs/http/ngx_http_scgi_module.html#scgi_busy_buffers_size).
The same situation happens in directive "scgi_temp_file_write_size" in https://nginx.org/en/docs/http/ngx_http_scgi_module.html#scgi_temp_file_write_size, and directive "scgi_max_temp_file_size" in https://nginx.org/en/docs/http/ngx_http_scgi_module.html#scgi_max_temp_file_size. They should all be equal or greater than the maximum of the value of "scgi_buffer_size" and "scgi_buffers" size.
What's more, the value of directive "scgi_busy_buffers_size" must be less than (number-of-scgi_buffers - 1)*size-of-scgi_buffers. This also should be recorded.