XIOS3: xios_server.exe tries to call MPI routine before MPI initialisation

[acc]

Just trying a few tests with XIOS3. Struggled to get a simple test_client.exe set-up going in detached mode.
Seems that the CTimer call at line 63 of server.cpp is calling a MPI routine (MPI_Wtime?) before MPI_Init has been called. Commenting out the Ctimer call gets things going.

[ymipsl]

Replying to acc:

Just trying a few tests with XIOS3. Struggled to get a simple test_client.exe set-up going in detached mode.
Seems that the CTimer call at line 63 of server.cpp is calling a MPI routine (MPI_Wtime?) before MPI_Init has been called. Commenting out the Ctimer call gets things going.

Thanks for this, we have probably a more permissive MPI library in which one we can use MPI_WTIME without MPI_Init. We will correct this quickly.
Note that test_client.exe is obsolete and we encourage userto use the "generic_testcase" instead.
Yann

[acc]

Note that test_client.exe is obsolete and we encourage userto use the "generic_testcase" instead.

Fair enough but, from outside, it is always useful to start with something simple and familiar. Are there instructions for the generic test case anywhere?

​This page is still "encouraging" the use of test_client

[jderouillat]

We manifestly have to update this page ! Waiting for this update :

The idea of the generic_testcase is to be more versatile at runtime.
Many parameters are set in the iodef.xml : global quantities such as ni, nj, nlev, the way to distribute data on MPI process clients (the domain which can be "lmdz", "nemo"), the mask management on domains/axis.
The code is available in src/test/generic_testcase.f90, the input files in generic_testcase.

$ ls generic_testcase/
context_atm.xml  context_grid_dynamico.xml  context_oce.xml  dynamico_grid.nc  iodef.xml  param.def
$ ls bin/generic_testcase.exe 
bin/generic_testcase.exe

Some others parameters such as the number of clients used must be set in param.def (nb_proc_atm). To launch with servers, you need to specify more process than specified for clients in param.def, the difference will be used as servers.

In the configuration below, 1 client and 1 server will be executed :

$ cat param.def 
&params_run
duration='4ts'
nb_proc_atm=1
nb_proc_oce=0
/
$ mpirun -np 2 ../bin/generic_testcase.exe 

Fields and files to write are specified in context_atm.xml, by default a single file is written with fields which exists on a domain x an axis, a domain, many axis, axis x axis (x axis, for field_XYZ):

    <file id="atm_output" output_freq="1ts" type="one_file" enabled="true">
      <field field_ref="field3D"    enabled="true"/>
      <field field_ref="field2D"    enabled="true"/>
      <field field_ref="field_X"    enabled="true"/>
      <field field_ref="field_Y"    enabled="true"/>
      <field field_ref="field_XY"  enabled="true"/>
      <field field_ref="field_Z"    enabled="true"/>
      <field field_ref="field_XYZ"  enabled="true"/>
      <field field_ref="field_XZ"   enabled="true"/>
      <field field_ref="field_YZ"   enabled="true"/>
    </file>

You can find other examples of context_atm.xml, especially with transformations, in xios_test_suite/TEST_SUITE/test_*/context_atm.xml (used for non regression test).

[jderouillat]

The first call to MPI_Wtime has been moved after the MPI_Init on servers.