I am reading data from a microcontroller via serial, at a baudrate of 921600.  I'm reading a large amount of ASCII csv data, and since it comes in so fast, the buffer get's filled and all the rest of the data gets lost before I can read it.  I know I could manually edit the pyserial source code for serialwin32 to increase the buffer size, but I was wondering if there is another way around it?
I can only estimate the amount of data I will receive, but it is somewhere around 200kB of data.
For me the problem was it was overloading the buffer when receiving data from the Arduino.
All I had to do was mySerialPort.flushInput() and it worked.
I don't know why mySerialPort.flush() didn't work. flush() must only flush the outgoing data?
All I know is mySerialPort.flushInput() solved my problems.
Pyserial buffer fills faster than I can read