dtrace discuss - Dec 2008 - Is it possible to attach several DTraces to a single process?

Hi,

Is it possible to attach dtrace to a single process twice or more times? (with
different scripts)?

Each time I tried, it fails with the message
"failed to grab pid 13407: process is traced"

I ended up with two simplest scripts

dtrace -n ''END { printf("BYE"); }'' -p 13407
dtrace -n ''BEGIN { printf("Hi there"); }'' -p 13407

but they failed with the same message.

Does this mean that it is impossible to attach several scripts to a single
process?
Or do I misunderstand something?

Thank you,
Vladimir
-- 
This message posted from opensolaris.org

Hey Vladimir,

You can''t have multiple dtrace(1M) invocations that use the -p option  
because each one will try to monitor and consume events about the  
process''s life-cycle such as loading modules and exiting. You can,  
however, have multiple DTrace scripts that observe a process by using  
the pid provider with that process''s id or other providers with an  
appropriate predicate.

Adam

On Dec 19, 2008, at 1:27 AM, Vladimir Kvashin wrote:
> Hi,
>
> Is it possible to attach dtrace to a single process twice or more  
> times? (with different scripts)?
>
> Each time I tried, it fails with the message
> "failed to grab pid 13407: process is traced"
>
> I ended up with two simplest scripts
>
> dtrace -n ''END { printf("BYE"); }'' -p 13407
> dtrace -n ''BEGIN { printf("Hi there"); }'' -p
13407
>
> but they failed with the same message.
>
> Does this mean that it is impossible to attach several scripts to a  
> single process?
> Or do I misunderstand something?
>
> Thank you,
> Vladimir
> -- 
> This message posted from opensolaris.org
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org

--
Adam Leventhal, Fishworks                        http://blogs.sun.com/ahl