[Bug runtime/6897] stap should assert valid PIDs for process(PID) probes

[dsmith at redhat dot com]

------- Additional Comments From dsmith at redhat dot com  2008-09-17 14:47 -------
(In reply to comment #0)
> When running a SystemTap script with process(PID) syntax where PID is
> non-existant,  I expected SystemTap to exit with an error message. However
> SystemTap seems happy enuf to start a probing section.

In the current implementation, the module will hang around.  The reason why it
doesn't exit is that pid-based probes at startup are treated much the same as
path-based probes.  If a thread doesn't exist at startup whose path matches,
that isn't an error, since a new thread could come into existence whose path
will match.  Note that we don't monitor new thread creation looking for pids -
that only happens at startup.

I can see the benefits of error'ing out here.  But, I do have a question.  Let's
say your script has 2 pid-based probes - one for pid 10000 and one for pid
50000.  At startup, pid 10000 exists, but pid 50000 doesn't.  Should the user
just receive an error message or should systemtap exit?

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6897

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