<defunct>: too many from pipe

[Alan Cox]

> I find, on ps -ef, that each system command leaves behind a
> processes marked <defunct> that remains until the daemon is
> stopped.  These are unaffected by kill -9 issued either from
> the destructor of the pipe class, or by me on the command
> line.  I have two questions:

They are waiting for you to wait for them and clean up.

> 1. Is there any way to get rid of these defunct processes
>    other than stopping the daemon?

man 2 waitpid

> 2. How many of these can pile up before my system crashes?

A dead process (Zombie) like that has few resources left, most of it has
been freed up already. In the end the system will stop you creating
processes rather than just crash