Description
Describe the bug
SSC will not always read scalar string variables correctly, often returning an empty string instead. Furthermore, if only writing scalar (string?) variables in a step, the SSC engine will crash.
To Reproduce
This example writes three variables from rank 0 and reads them on rank 1. firststring and secondstring are scalar strings, someothertype is an int array.
#include <adios2.h>
#include <iostream>
#include <mpi.h>
#include <string>
#include <vector>
int
main( int argsc, char ** argsv )
{
MPI_Init( &argsc, &argsv );
int global_mpi_rank, global_mpi_size;
MPI_Comm_rank( MPI_COMM_WORLD, &global_mpi_rank );
MPI_Comm_size( MPI_COMM_WORLD, &global_mpi_size );
int local_mpi_rank, local_mpi_size;
int color = global_mpi_rank < 2 ? global_mpi_rank : MPI_UNDEFINED;
MPI_Comm local_comm;
MPI_Comm_split( MPI_COMM_WORLD, color, local_mpi_rank, &local_comm );
MPI_Comm_rank( local_comm, &local_mpi_rank );
MPI_Comm_size( local_comm, &local_mpi_size );
std::string engine_type = "ssc";
adios2::ADIOS adios{ local_comm };
adios2::IO IO = adios.DeclareIO( "IO" );
IO.SetEngine( engine_type );
#define PUT_INT true
switch( color )
{
case 0:
{
// write
adios2::Engine engine = IO.Open( "stream", adios2::Mode::Write );
engine.BeginStep();
#if PUT_INT
auto othervariable = IO.DefineVariable< int >(
"someothertype", { 10 }, { 0 }, { 10 } );
std::vector< int > v( 10, 1234 );
engine.Put( othervariable, v.data() );
#endif
auto var1 = IO.DefineVariable< std::string >( "firststring" );
auto var2 = IO.DefineVariable< std::string >( "secondstring" );
std::string firststring = "firststring";
std::string secondstring = "secondstring";
engine.Put( var1, firststring );
engine.Put( var2, secondstring );
engine.EndStep();
engine.Close();
}
break;
case 1:
{
// read
adios2::Engine engine = IO.Open( "stream", adios2::Mode::Read );
engine.BeginStep();
auto var1 = IO.InquireVariable< std::string >( "firststring" );
auto var2 = IO.InquireVariable< std::string >( "secondstring" );
std::string firststring;
std::string secondstring;
engine.Get( var1, firststring );
engine.Get( var2, secondstring );
#if PUT_INT
auto othervariable = IO.InquireVariable< int >( "someothertype" );
std::vector< int > v( 10 );
engine.Get( othervariable, v.data() );
#endif
engine.EndStep();
std::cout << " First Variable:\t" << firststring
<< "\nSecond Variable:\t" << secondstring << std::endl;
#if PUT_INT
std::cout << "Int variable:\t" << v[ 0 ] << std::endl;
#endif
engine.Close();
}
break;
case MPI_UNDEFINED:
break;
}
MPI_Finalize();
}Output:
First Variable:
Second Variable:
Int variable: 1234
Output if setting #define PUT_INT false:
First Variable:
Second Variable:
terminate called after throwing an instance of 'nlohmann::detail::type_error'
what(): [json.exception.type_error.305] cannot use operator[] with a string argument with number
Expected behavior
Setting the engine to sst gives the expected output:
First Variable: firststring
Second Variable: secondstring
Int variable: 1234
Desktop (please complete the following information):
- OS/Platform: Ubuntu 20.10
- Build
c++ (Ubuntu 10.2.0-13ubuntu1) 10.2.0, currentmaster(commit hash7854b5fcb34d1fe7a346261a291460fe47e2987e)
Additional context
Scalar string variables will not always fail to read values correctly in SSC. When I tried SSC for openPMD, one scalar string variable was read incorrectly (the first one, to be precise). All subsequent ones were read correctly. In this example however, both scalar strings seem to behave wrongly.
Following up
Was the issue fixed? Please report back.
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