Application Not Responding to Messages Logic

The Application Not Responding to Messages dialog, or BadApp dialog as it is sometimes referred to, appears after Ctrl-Esc has been hit and the system has not been able to display the task list.

The essential logic for this processing is as follows:

• Ctrl-Esc is hit and 5 second timer is started.

• If the task list appears before the time-out then all is well, if not we check for who might be holding things up.

• We try for 5 seconds to obtain the User PM Semaphore. If unsuccessful then the Pid, Tid and Session Id of the owner is saved in the QHPSTRUCT.

• If pmqsyslock is owned then the Pid, Tid and Session Id of the owner is saved in the QHPSTRUCT.

• If pmqfocus is owned then the Pid, Tid and Session Id of the owner is saved in the QHPSTRUCT.

• We now enter a second wait of a further 3 seconds, after which, we build a second QHPSTRUCT.

• If the Tid and Pid are different and we have not yet had an acknowledgement from the task list then we wait a further 12 seconds, on the assumption the processing is slow, but not hung.

• If the Tid and Pid are the same or we have expired on our third time-out then we set fBadAppDialog true and reset the cause for the hang:

  • If User_Sem held then release User_Sem

  • if system queue locked then reset pmqsyslock

  • if focus owner hung, then reset pmqfocus
  Report the hanging application in the BadApp dialog.

This processing is illustrated in the following two diagrams:

BadApp Dialog Logic

Query Hung Process Logic

The flags in the QHPSTRUCT indicate the detected reason for hanging. These may be a combination of:

┌────────────────────┬────────┬────────────────────────────────────────┐│Name                │Bit Mask│Description                             │
├────────────────────┼────────┼────────────────────────────────────────┤
│QHP_SYSQUEUELOCK    │0x0001  │System Queue Locked                     │
├────────────────────┼────────┼────────────────────────────────────────┤
│QHP_SENDMSGLOCK     │0x0002  │Waiting for a response to WinSendMsg    │
├────────────────────┼────────┼────────────────────────────────────────┤
│QHP_CLIPBRDLOCK     │0x0004  │                                        │
├────────────────────┼────────┼────────────────────────────────────────┤
│QHP_WINDOWLOCKED    │0x0008  │                                        │
├────────────────────┼────────┼────────────────────────────────────────┤
│QHP_VISRGNLOCKED    │0x0010  │                                        │
├────────────────────┼────────┼────────────────────────────────────────┤
│QHP_LOCKWINDOWUPDATE│0x0020  │                                        │
├────────────────────┼────────┼────────────────────────────────────────┤
│QHP_FSRSUSERHANG    │0x4000  │Waiting for the User_Sem                │
├────────────────────┼────────┼────────────────────────────────────────┤
│QHP_INPUTPROCESSED  │0x8000  │                                        │
└────────────────────┴────────┴────────────────────────────────────────┘