Home/ Questions/Q 88657
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-10T22:35:39+00:00

We have an application that has one or more text console windows that all

  • 0

We have an application that has one or more text console windows that all essentially represent serial ports (text input and output, character by character). These windows have turned into a major performance problem in the way they are currently code… we manage to spend a very significant chunk of time in them.

The current code is structured by having the window living its own little life, and the main application thread driving it across ‘SendMessage()’ calls. This message-passing seems to be the cause of incredible overhead. Basically, having a detour through the OS feels to be the wrong thing to do.

Note that we do draw text lines as a whole where appropriate, so that easy optimization is already done.

I am not an expert in Windows coding, so I need to ask the community if there is some other architecture to drive the display of text in a window than sending messages like this? It seems pretty heavyweight.

Note that this is in C++ or plain C, as the main application is a portable C/C++/some other languages program that also runs on Linux and Solaris.

We did some more investigations, seems that half of the overhead is preparing and sending each message using SendMessage, and the other half is the actual screen drawing. The SendMessage is done between functions in the same file…

So I guess all the advice given below is correct:

  • Look for how much things are redrawn
  • Draw things directly
  • Chunk drawing operations in time, to not send every character to the screen, aiming for 10 to 20 Hz update rate of the serial console.

Can you accept ALL answers?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. I agree with Will Dean that the drawing in a console window or a text box is a performance bottleneck by itself. You first need to be sure that this isn’t your problem. You say that you draw each line as a whole, but even this could be a problem, if the data throughput is too high.

    I recommend that you don’t use the SendMessage to pass data from the main application to the text window. Instead, use some other means of communication. Are these in the same process? If not, you could use shared memory. Even a file in the disk could do in some circumstances. Have the main application write to this file and the text console read from it. You could send a SendMessage notification to the text console to inform it to update the view. But do not send the message whenever a new line arrives. Define a minimum interval between two subsequent updates.

    • 0