Recognize frozen applications (Watchdog)

Windows with Delphi
Windows API (94)
Windows Filesystem (41)
Windows Forms (69)
Windows Graphics (38)

Recognize frozen applications (Watchdog)

This article has not been rated yet. After reading, feel free to leave comments and rate it.

Question:

I am developing a sort of watchdog and I need to programatically check from an application, if another application is not responding. How can I do this?

Answer:

Try by sending a message with SendMessageTimeOut. If the another application is not responding, there is a timout. The example below searches for application 'MyApplication' in the main window's caption bar and gives it 3 seconds to respond to a message.

function AppFrozen(H: HWND) : Boolean;
var
  dwResult: DWord;
const
  timeout = 3000; // ms
begin
  AppFrozen := SendMessageTimeout(H, WM_NULL, 0, 0, 
                                  SMTO_ABORTIFHUNG or SMTO_BLOCK, 
                                  timeout, dwResult) <> 0
end;


var
  H: HWND;

begin
  // enumerate top level windows or search for an
  // application that you are monitoring
  H := FindWindow(nil, 'MyApplication');
  if H<>0 then
    if AppFrozen(H) then
      ShowMessage('MyApplication is Frozen!')
end.

You don't like the formatting? Check out SourceCoder then!

Comments:

Email address (not necessary): Rate as	Hide my email when showing my comment. Please notify me once a day about new comments on this topic. Please provide a valid email address if you select this option.

It seems that you are from Los Angeles, US . Info/ Feedback on this	Show city and country Show country only Hide my location
You can mark text as 'quoted' by putting [quote] .. [/quote] around it.
Please type in the code:
Add a picture: Please do not post inappropriate pictures. Inappropriate pictures include pictures of minors and nudity. The owner of this web site reserves the right to delete such material.


	Search: