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Subject: Re: [OMPI devel] RFC: MCA param registration errors
From: George Bosilca (bosilca_at_[hidden])
Date: 2011-11-02 13:23:40


As it has been said, this is not something supposed to make it in a release. On the unfortunate case where it does, always having a show_help will ensure a quick complaint on one of our mailing lists and increase the probability of a [very] quick fix.

  george.

On Nov 2, 2011, at 06:26 , TERRY DONTJE wrote:

>
>
> On 11/1/2011 7:48 PM, Jeff Squyres wrote:
>>
>> So this was slightly different than the opinion that was discussed on the call today, which was 2. The rationale for #2 was to punish developers, but if such a bug did make it through to production, users wouldn't be annoyed with show_help messages all the time.
>>
>> Does anyone have strong opinions here? I don't.
>>
>> I offer the following two points:
>>
>> - this is a coding error on the OMPI developer
>> - it's pretty rare
>>
> I think a show_help + return is very helpful in this case. I wouldn't think that we'd run into this case that much and it would seem that it would be a rare occurance that one could just fix when they run into it. However, since there was some opposition to having show_help messages possibly coming up all over the place I thought a fall back of only doing the show_help on enable_debug builds was a reasonable middle ground.
>
> --td
>>
>> On Nov 1, 2011, at 7:30 PM, George Bosilca wrote:
>>
>>> 1
>>>
>>> george.
>>>
>>> On Nov 1, 2011, at 17:23 , Jeff Squyres wrote:
>>>
>>>> Can you clarify -- I can parse your text multiple ways. Which are you voting for?
>>>>
>>>> 1. show_help + return error code in all cases.
>>>> 2. if OPAL_ENABLE_DEBUG, show_help + exit(1), else silently return error code.
>>>> 3. show_help. if OPAL_ENABLE_DEBUG, exit(1), else return error code.
>>>>
>>>>
>>>>
>>>> On Nov 1, 2011, at 4:50 PM, George Bosilca wrote:
>>>>
>>>>> This is a much saner solution. We [mostly] stayed away from calling exit deep into our libraries, there is no reason to add it now. I'll vote in favor of show_help + return code.
>>>>>
>>>>> george.
>>>>>
>>>>> On Nov 1, 2011, at 15:14 , Jeff Squyres wrote:
>>>>>
>>>>>> We talked about this on the call today.
>>>>>>
>>>>>> A good suggestion was made: call show_help/opal_finalize/exit only when OPAL_ENABLE_DEBUG is true. Otherwise, return an error code.
>>>>>>
>>>>>> If no one objects to this, I'll commit this tomorrow.
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Oct 31, 2011, at 4:16 PM, Jeff Squyres wrote:
>>>>>>
>>>>>>> WHAT: what to do if registering an MCA param results in an error?
>>>>>>>
>>>>>>> WHERE: opal/mca/base/mca_base_param.c
>>>>>>>
>>>>>>> WHY: MCA param re-registration issues should be treated as OMPI developer errors
>>>>>>>
>>>>>>> WHEN: COB Friday, 4 Nov 2011
>>>>>>>
>>>>>>> -----------------
>>>>>>>
>>>>>>> Short version:
>>>>>>>
>>>>>>> Re-registering an MCA param to be a different type (e.g., it was initially registered to be a string, but was later re-registered to be an int) should be treated as an OMPI developer error, and should opal_finalize()/exit(1).
>>>>>>>
>>>>>>> More details:
>>>>>>>
>>>>>>> A mistaken MCA param re-registration recently caused an orted segv.
>>>>>>>
>>>>>>> The MCA param subsystem was fixed to avoid this segv, but silently convert the MCA param to the newly-registered type. Upon reflection and some discussion, this seems to be a bad idea. Instead, we should loudly complain via a show_help message and then exit(1).
>>>>>>>
>>>>>>> Specifically: this kind of behavior is clearly an error and should be fixed. Unfortunately, in most cases, we don't actually check the return value from MCA param registration functions, so if we change the MCA param function to simply return a non OPAL_SUCCESS status, it's unlikely that anyone will notice until some code tries to read the param value, likely still resulting in a segv.
>>>>>>>
>>>>>>> Does anyone have heartburn if I change the error behavior to opal_finalize()/exit(1)?
>>>>>>>
>>>>>>> --
>>>>>>> Jeff Squyres
>>>>>>> jsquyres_at_[hidden]
>>>>>>> For corporate legal information go to:
>>>>>>> http://www.cisco.com/web/about/doing_business/legal/cri/
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> devel mailing list
>>>>>>> devel_at_[hidden]
>>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>>>>>>
>>>>>> --
>>>>>> Jeff Squyres
>>>>>> jsquyres_at_[hidden]
>>>>>> For corporate legal information go to:
>>>>>> http://www.cisco.com/web/about/doing_business/legal/cri/
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> devel mailing list
>>>>>> devel_at_[hidden]
>>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>>>>>
>>>>> _______________________________________________
>>>>> devel mailing list
>>>>> devel_at_[hidden]
>>>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>>>>
>>>> --
>>>> Jeff Squyres
>>>> jsquyres_at_[hidden]
>>>> For corporate legal information go to:
>>>> http://www.cisco.com/web/about/doing_business/legal/cri/
>>>>
>>>>
>>>> _______________________________________________
>>>> devel mailing list
>>>> devel_at_[hidden]
>>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>>>
>>> _______________________________________________
>>> devel mailing list
>>> devel_at_[hidden]
>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>>
>
> --
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> Terry D. Dontje | Principal Software Engineer
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> Oracle - Performance Technologies
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