High CPU usage

[sfrazor 3]

Using OverbyteIcsSnippets as an example.  Websocket CLIent section, after wsconnect is successful it falls in to this loop.
 

            while NOT AbortFlag do begin
                 Application.ProcessMessages;
                 if Application.Terminated then Break;
                 if IcsTestTrgTick64(TrgTimerEnd) then Break;
            end;

 

Mine is a console app and I do something almost identicle to this on startup.  I connect then fall in to the main thread loop waiting for a signal to end.

My application runs at 48%  cpu usage just like the example.

I realize this is a tight loop.

Running as-is the OnWSFrameRecv will receive a 50M file in a few seconds.
However when I try to address the high cpu issue and add a simple sleep(5), which drops the CPU down to less than 5 percent. The 50M file receive via the OnWSFrameRecv event now slows down to 9 minutes.
Its like the receive is blocking.  I'm not sure why a simple sleep would do this.  Is the sleep cascading in the tight loop and causing the overall main thread to sleep much longer than the 5ms maybe?
I know there is missing info here. The application is quite large but the websocket connect and receive is very basic.  I rebuilt excluding throttling in the library but it didn't make any difference.
Is there a better way this not CPU intensive to loop and wait for the termination?

 

The goal is to receive large files via WS and not have the appl;ication idle at this high usage.

Any help would be appreciated. 

 

Regards
 

Edited March 6 by sfrazor

[Angus Robertson 625]

Try Sleep(0) or MsgWaitForMultipleObjects before calling the pump, that is what the ICS synchronous methods do.  BTW, Snippets is simple examples. 

 

Angus

 

[sfrazor 3]

  On 3/6/2025 at 7:27 PM, Angus Robertson said:

Try Sleep(0) or MsgWaitForMultipleObjects before calling the pump, that is what the ICS synchronous methods do.  BTW, Snippets is simple examples. 

 

I was sifting through the source looking for examples of this very issue.  I found MsgWaitForMultipleObjects right after you posted.  I had tried sleep(0) with no success. But the MsgWaitForMultipleObjects worked and now the CPU is back down to .3 % and file transfers are back to their normal fast speed.

Thanks!

[Anders Melander 1951]

  On 3/6/2025 at 7:27 PM, Angus Robertson said:

Try Sleep(0)

https://joeduffyblog.com/2006/08/22/priorityinduced-starvation-why-sleep1-is-better-than-sleep0-and-the-windows-balance-set-manager/

[zed 17]

  On 3/6/2025 at 11:36 PM, Anders Melander said:

https://joeduffyblog.com/2006/08/22/priorityinduced-starvation-why-sleep1-is-better-than-sleep0-and-the-windows-balance-set-manager/

The behavior of the Sleep function was changed in Windows Server 2003, making it safe to use Sleep(0) — unless you're writing code for Windows XP. 

 

https://learn.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-sleep

[Anders Melander 1951]

  On 3/7/2025 at 9:22 AM, zed said:

The behavior of the Sleep function was changed in Windows Server 2003, making it safe to use Sleep(0)

Thanks. I didn't get that memo 🙂