[mpich-discuss] Hydra issues

[Scott Atchley]

Only rank 0 gets stdin. Is it blocking on read()?

Scott

On Aug 26, 2009, at 3:22 PM, Darius Buntinas wrote:

> This may be related:  On trunk, I get the output from rank 1
> immediately, but I only get rank 0 output when the app exits.
>
> Maybe the buffer settings on the proxy aren't set correctly for rank  
> 0's
> stdout socket?
>
> -d
>
> On 08/26/2009 01:55 PM, Scott Atchley wrote:
>> On Aug 26, 2009, at 1:38 PM, Dave Goodell wrote:
>>
>>> On Aug 26, 2009, at 9:19 AM, Dave Goodell wrote:
>>>
>>>> On Aug 26, 2009, at 8:58 AM, Scott Atchley wrote:
>>>>
>>>>> Ok, I was not patient enough. If I let it run, it eventually  
>>>>> starts.
>>>>> The actual walltime is nearly the same as when I use proxies, but
>>>>> the stdout is delayed until the application completes.
>>>>
>>>> I think I know why this happens.  It ought to be fixed once I  
>>>> finish
>>>> up some Hydra I/O work that was mostly done by one of our students
>>>> this summer.  The work is basically done and lives on a development
>>>> branch but it needs a little bit of cleanup and to be rebased onto
>>>> the current trunk.
>>>
>>> I was mistaken on this particular issue.  There was another  
>>> buffering
>>> issue that we ran into during the student's work and I was  
>>> thinking of
>>> that one.  There isn't any current hydra-side fix for this that I  
>>> know
>>> of.
>>>
>>> However you could use one of the various workarounds for this,  
>>> such as
>>> an LD_PRELOADed setvbuf call:
>>> http://lists.gnu.org/archive/html/bug-coreutils/2008-11/ 
>>> msg00164.html
>>
>> This does not change the behavior.
>>
>> I am still stumped as to why there is no delay when using persistent
>> (launch-mode=2) versus a delay with no proxies (launch-mode=1).
>>
>> Scott