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[Bug runtime/6897] stap should assert valid PIDs for process(PID) probes
- From: "dsmith at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 17 Sep 2008 14:47:17 -0000
- Subject: [Bug runtime/6897] stap should assert valid PIDs for process(PID) probes
- References: <20080917112256.6897.srikar@linux.vnet.ibm.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- 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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