dtrace discuss - Mar 2007 - DTrace Probe Timeout

Hi,
Just wondering whether anyone knows how to timeout a dtrace script if a 
probe doesn''t fire within a specific time?

I''m basically looking to probe a process to ensure that it is still
firing
syscalls.  I will then wrap a shell script around this for automated 
alerting processes.  However I have been unable to find a way of timing 
out the probe when there are no syscalls firing.

Thanks for any help with this

Regards
Jon

This communication is for informational purposes only. It is not intended as an
offer or solicitation for the purchase or sale of any financial instrument or as
an official confirmation of any transaction. All market prices, data and other
information are not warranted as to completeness or accuracy and are subject to
change without notice. Any comments or statements made herein do not necessarily
reflect those of JPMorgan Chase & Co., its subsidiaries and affiliates.

This transmission may contain information that is privileged, confidential,
legally privileged, and/or exempt from disclosure under applicable law. If you
are not the intended recipient, you are hereby notified that any disclosure,
copying, distribution, or use of the information contained herein (including any
reliance thereon) is STRICTLY PROHIBITED. Although this transmission and any
attachments are believed to be free of any virus or other defect that might
affect any computer system into which it is received and opened, it is the
responsibility of the recipient to ensure that it is virus free and no
responsibility is accepted by JPMorgan Chase & Co., its subsidiaries and
affiliates, as applicable, for any loss or damage arising in any way from its
use. If you received this transmission in error, please immediately contact the
sender and destroy the material in its entirety, whether in electronic or hard
copy format. Thank you.
 
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://mail.opensolaris.org/pipermail/dtrace-discuss/attachments/20070309/d600678e/attachment.html>

Jonathan,

The profile provider gives timer based probe firing.  Let''s say you 
wanted to exit after 30 minutes:

profile:::tick-30min
{
   exit(0);
}

Will fire "every" 30 minutes, but since the probe clause has an
exit(0),
you''re only worried about the first 30 minutes.

Which brings up a little hitch in this method.  Every D program shares 
the same probes, so if your host happens to be running two scripts that 
both happen to be using the tick-30min probe, both scripts will react to 
the same firing, no matter when they were started. For example, if you 
started one of the scripts at 1:00PM, and the second one at 1:15PM, they 
would both exit at 1:30PM.  So as long as you''re sure you''re
script is
the only one using that exact tick timer, or more precisely, as long as 
yours was first, the first pass will be accurate.

Chip

jonathan.a.spinks at jpmorgan.com wrote:
>
> Hi,
> Just wondering whether anyone knows how to timeout a dtrace script if 
> a probe doesn''t fire within a specific time?
>
> I''m basically looking to probe a process to ensure that it is
still
> firing syscalls.  I will then wrap a shell script around this for 
> automated alerting processes.  However I have been unable to find a 
> way of timing out the probe when there are no syscalls firing.
>
> Thanks for any help with this
>
> Regards
> Jon
> This communication is for informational purposes only. It is not 
> intended as an offer or solicitation for the purchase or sale of any 
> financial instrument or as an official confirmation of any 
> transaction. All market prices, data and other information are not 
> warranted as to completeness or accuracy and are subject to change 
> without notice. Any comments or statements made herein do not 
> necessarily reflect those of JPMorgan Chase & Co., its subsidiaries 
> and affiliates. This transmission may contain information that is 
> privileged, confidential, legally privileged, and/or exempt from 
> disclosure under applicable law. If you are not the intended 
> recipient, you are hereby notified that any disclosure, copying, 
> distribution, or use of the information contained herein (including 
> any reliance thereon) is STRICTLY PROHIBITED. Although this 
> transmission and any attachments are believed to be free of any virus 
> or other defect that might affect any computer system into which it is 
> received and opened, it is the responsibility of the recipient to 
> ensure that it is virus free and no responsibility is accepted by 
> JPMorgan Chase & Co., its subsidiaries and affiliates, as applicable, 
> for any loss or damage arising in any way from its use. If you 
> received this transmission in error, please immediately contact the 
> sender and destroy the material in its entirety, whether in electronic 
> or hard copy format. Thank you.
> ------------------------------------------------------------------------
>
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org

jonathan.a.spinks at jpmorgan.com wrote:
> 
> I''m basically looking to probe a process to ensure that it is
still
> firing syscalls.  I will then wrap a shell script around this for 
> automated alerting processes.  However I have been unable to find a way 
> of timing out the probe when there are no syscalls firing.
> 
The usual way is by using the profile provider, usually w/ a tick probe:

See http://docs.sun.com/app/docs/doc/817-6223/6mlkidlf7?a=view

dtrace:::BEGIN
{
	i = 10;
}

profile:::tick-1sec
/i > 0/
{
	i--;
}

profile:::tick-1sec
/i == 0/
{
	exit(0);
}

Add the above to your script and it will run for only 10 seconds.


-- 
Bart Smaalders			Solaris Kernel Performance
barts at cyber.eng.sun.com		http://blogs.sun.com/barts

Jonathan,

I like the one Bart showed us better for two reasons: 1) you don''t have
to worry about the start-up problem, and 2) I was just thinking that you 
might have meant that you wanted to exit after X amount of time since 
the last syscall.  In the script from the DTrace Guide, all you would 
need to do is reset the index "i" back to the starting value in the 
syscall''s probe clause.

Despite the temptation to believe that the single "tick-30min" probe
is
more efficient, the difference is extremely insignificant.

Chip

Bart Smaalders wrote:
> jonathan.a.spinks at jpmorgan.com wrote:
>>
>> I''m basically looking to probe a process to ensure that it is
still
>> firing syscalls.  I will then wrap a shell script around this for 
>> automated alerting processes.  However I have been unable to find a 
>> way of timing out the probe when there are no syscalls firing.
>>
>
> The usual way is by using the profile provider, usually w/ a tick probe:
>
> See http://docs.sun.com/app/docs/doc/817-6223/6mlkidlf7?a=view
>
> dtrace:::BEGIN
> {
>     i = 10;
> }
>
> profile:::tick-1sec
> /i > 0/
> {
>     i--;
> }
>
> profile:::tick-1sec
> /i == 0/
> {
>     exit(0);
> }
>
> Add the above to your script and it will run for only 10 seconds.
>
>