[Halld-offline] Fwd: r7587 - trunk/sim-recon/src/libraries/TRACKING

[David Lawrence]

Hi Curtis,

     I have created a new issue in Mantis to review the existing STL 
sort calls in our reconstruction to ensure they do not have the 
potential of having a similar bug.

https://halldnew.jlab.org/mantisbt/view.php?id=50

Regards,
-David

On 3/17/11 12:14 PM, Curtis A. Meyer wrote:
> Hi David -
>
>     does it make sense to open a "general ticket" in Mantis about the 
> more general
> affects of this issue?
>
>   Curtis
> On 3/17/11 11:23 AM, David Lawrence wrote:
>>
>> Hi All,
>>
>>     I've just committed a fix to the seg. fault/hang problem based on 
>> Richard's analysis. This is slightly different than the fix Richard 
>> suggested. It avoids the 80bit/64bit comparison issue by 
>> pre-calculating the values to be compared rather than doing it in the 
>> sort algorithm itself. This should also speed things up a little 
>> since DVector3::Perp() is not being called repeatedly during the sort 
>> for the same object.
>>
>>     I have been able to run through my one reliably-problematic event 
>> using the new code without any problem. If anyone notices an issue, 
>> please let me know.
>>
>>     This problem has been marked as resolved in Mantis.
>>
>> Regards,
>> -David
>>
>> -------- Original Message --------
>> Subject: 	r7587 - trunk/sim-recon/src/libraries/TRACKING
>> Date: 	Thu, 17 Mar 2011 11:16:40 -0400
>> From: 	Hall-D.SVN.Repository at jlab.org
>> To: 	davidl at jlab.org, brash at pcs.cnu.edu, wolin at jlab.org, 
>> zisis at uregina.ca, mashephe at indiana.edu, remitche at indiana.edu, 
>> zihlmann at jlab.org, somov at jlab.org, staylor at jlab.org
>>
>>
>>
>> Author: davidl
>> Date: 2011-03-17 11:16:39 -0400 (Thu, 17 Mar 2011)
>> New Revision: 7587
>>
>> Modified:
>>     trunk/sim-recon/src/libraries/TRACKING/DTrackCandidate_factory_CDC.cc
>> Log:
>> This is a fix for the seg. fault/hang problem that has been plaguing us
>> for the last ~4 months. It precalculates the values used in the comparison
>> in the SortIntersections routine to avoid issues with values calculated
>> with 80bit precision being compared with values having been copied to and
>> from a 64bit register. See the report on the GlueX wiki here:
>>
>> http://www.jlab.org/Hall-D/software/wiki/index.php/Diagnosing_segmentation_faults_in_reconstruction_software
>>
>>
>>
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>
>
> -- 
> Prof. Curtis A. Meyer		Department of Physics
> Phone:	(412) 268-2745		Carnegie Mellon University
> Fax:	(412) 681-0648		Pittsburgh PA 15213-3890
> cmeyer at ernest.phys.cmu.edu	http://www.curtismeyer.com/
>
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