WatchCat is a program to recover OS/2 2.x and OS/2 3.x from some kind of hang by killing applications.

WatchCat is useful to any OS/2 user in the following situations:

The Presentation Manager (PM) is blocked. Due to the single message queue of OS/2 a single ill-behaved PM program might block all PM programs in the system and prevent any program from getting user input. Therefore it is impossible to end the corrupt task or to save data in other programs. You can press Ctrl-ESC but this does not help in all situations. Due to the Full-Screen nature of WatchCat those ill-behaved programs can be killed from within WatchCat.

There are several reasons why the PM might hang:

• An ill-behaved PM program
• An ill-behaved Windows program in a WIN-OS/2 session
• Erroneous Workplace Shell objects.
  • Even though OS/2 has become much more stable with Version 3, there are still situations where the PM is blocked:
    • The PM user-interface is blocked because of a system-modal dialog box that cannot be closed.
    • User input is impossible because of a high priority process or a process that is doing a lot of swapping.
• Displaying process information in a non-cryptic easy-to-understand way helping you to learn more about OS/2 and its processes.

WatchCat is also interesting to programmers in the following situations:

• Display all PStat-info about modules, processes, threads, etc. WatchCat periodically updates all this information. It is quick and easy to use without any PM overhead, by using the CuTe technology.
• Display all WatchCat information on a terminal and control WatchCat even if OS/2 crashed. Open a (windowed) remote shell on the hanging PC. (registered version only).
• Kill threads or change the priority of threads dynamically. (1st Aid Package only).
• Disable Ctrl-Alt-Del or use Ctrl-Alt-Del to activate WatchCat (registered version only).
• We are using WatchCat ourselves many times a day:
  • View the number of threads in an application.
  • Do all threads have the correct priority?
  • View the process hierarchy. Are all child processes started correctly?
  • Is my program really using the right DLL? Which DLL are used and what path do the DLL have?
  • Use WatchCat as a task switcher when Ctrl-ESC does not work.
  • Don't be afraid to use the debugger for critical actions (e.g. breakpoints in the window procedure), most hang-ups can be recovered.
  • Does my application consume much CPU time?
  • My application stops. Is it an endless loop or a deadlock?
• You may use it in special cases for debugging: Send your debugging text to WatchCat to avoid any additional PM message passing. This may be useful in some PM and WPS applications.
• WatchCat can be extended with its own modules via a DLL and a documented C-API. or via the simple and documented WatchCat C++ window framework.

WatchCat needs a very small amount of CPU-time. You don't see it and you won't notice it. But it is there if you need it.