Here's what I found:
> In Java, a long is always 64 bits. In C and Objective-C, a long might be 64
> bits, or it might be 32 bits, or (in less common cases) it might be something
> else entirely; the C standard doesn't specify an exact bit width.
So we may need a configure test to map the Java "long" data type to the right
thing to get int64_t?
On Feb 20, 2013, at 7:41 AM, Jeff Squyres (jsquyres) <jsquy...@cisco.com> wrote:
> I guess the question is whether a java "long" is equivalent to a C "long",
> "long long", or "long int"...
>
> Do you know? (I'm not much of a Java guy)
>
>
> On Feb 19, 2013, at 7:22 PM, Steve Angelovich <sangelov...@lgc.com> wrote:
>
>> All,
>>
>> We ran into a problem using openmpi from java with a Java data type of long
>> when doing bcast and reduce operations.
>>
>> *** An error occurred in MPI_Allreduce: the reduction operation MPI_MIN is
>> not defined on the MPI_LONG_INT datatype
>> *** reported by process [211105480705,0]
>> *** on communicator MPI COMMUNICATOR 4 DUP FROM 0
>> *** MPI_ERR_OP: invalid reduce operation
>> *** MPI_ERRORS_ARE_FATAL (processes in this communicator will now abort,
>> *** and potentially your MPI job)
>> 3 more processes have sent help message help-mpi-errors.txt /
>> mpi_errors_are_fatal
>> Set MCA parameter "orte_base_help_aggregate" to 0 to see all help / error
>> messages
>>
>> Looking at ompi/mpi/java/c/mpi_Datatype.c it looks like an MPI_LONG_INT type
>> is being used. It seems this should be an MPI_LONG_LONG. If I change this
>> data type I'm able to do bcast and reduce operations via the java interface.
>> Does this look like a bug or am I missing something else?
>>
>>
>>
>> --- openmpi-1.7rc6/ompi/mpi/java/c/mpi_Datatype.c 2013-02-19
>> 15:44:13.299046000 -0600
>> +++ openmpi-1.9a1r28069/ompi/mpi/java/c/mpi_Datatype.c 2013-02-17
>> 20:00:14.000000000 -0600
>> @@ -60,7 +60,7 @@
>>
>> MPI_Datatype Dts[] = { MPI_DATATYPE_NULL, MPI_BYTE, MPI_SHORT,
>> MPI_SHORT, MPI_BYTE, MPI_INT,
>> - MPI_LONG_LONG, MPI_FLOAT, MPI_DOUBLE,
>> + MPI_LONG_INT, MPI_FLOAT, MPI_DOUBLE,
>> MPI_PACKED, MPI_LB, MPI_UB,
>> MPI_BYTE };
>>
>>
>> Thanks,
>> Steve
>>
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>
> --
> Jeff Squyres
> jsquy...@cisco.com
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