Running application not listed in Task Manager

The first time I have seen this... The application stopped responding,
so naturally Task Manager was used to shut it down. But, surprise, the
application was not listed in Task Manager, so it could not be shut
down. A minute or two later, before restarting Windows, somehow
magically that application showed up (restored). Then clicking within
the window magically caused it to disappear and shut down.

I was doing some typical weird stuff with the operating system, but
still that's not unusual here and it's the first time a program has gone
unresponsive without showing up in Task Manager.

John Doe wrote:
The first time I have seen this... The application stopped responding,
so naturally Task Manager was used to shut it down. But, surprise, the
application was not listed in Task Manager, so it could not be shut
down. A minute or two later, before restarting Windows, somehow
magically that application showed up (restored). Then clicking within
the window magically caused it to disappear and shut down.

I was doing some typical weird stuff with the operating system, but
still that's not unusual here and it's the first time a program has gone
unresponsive without showing up in Task Manager.

There is a state machine for processes.

In theory, the state it's in should be reflected
in its Task Manager entry.

It can be suspended. It can be a "zombie". Zombie
has been a concept, even back on my old Unix boxes in
1990. Zombies were seen on Win10, in some of the
early versions. I haven't seen a Zombie in quite
a while.

Windows has more than a few holes in it.

Windows does not care if metadata in the process
table is corrupt. I have seen a process claim to be
system or PID4, with "no name" while it is displayed
in Task Manager. and as a consequence, I have
no idea (for sure) what it actually is.

Windows allows this...

when it should not. Such processes should be
terminated with prejudice, for machine safety.

Maybe today, Windows Defender would not allow
that to happen, but because I didn't purposely
do that, I have no idea how to test for that one
now.

I was interested in the observation at the time,
because of the "bad hygiene" such a discovery
implies. That the OS isn't watchful enough for
practical purposes. Things like this *should not happen*.

Your discovery would be a similar one. A process
which has seemingly managed to avoid a process
status scan for more than one scan interval,
leaving absolutely no entry in its wake. This
means the state machine could be stuck in a
kernel call or something. I don't want to interpret
the symptoms, except to say stuff like this
should not happen. Bad design. Bad. Naughty.
Idiotic even.

The scheduler knows it is there, because it
was given enough cycles to do stuff and
re-appear.

"Is there a thing more reliable than Task Manager?"

Well, who the **** knows.

Do we have to write our own ?

Paul