Some fixes

Signed-off-by: Igoshev, Iaroslav <[email protected]>

docs/troubleshooting.rst

@@ -200,14 +200,15 @@ to start the number of workers exceeding the number of physical cores.
 
 To get more information about the flags refer to `Open MPI's mpiexec`_ command documentation.
 
-.. _`Open MPI's mpiexec`: https://www.open-mpi.org/doc/v3.1/man1/mpiexec.1.php
-.. _`issue`: https://github.com/modin-project/unidist/issues
+Shared object store for MPI backend is not supported in C/W model for MPICH version less than 4.2.0
+---------------------------------------------------------------------------------------------------
 
-
-Shared object store is not supported in C/W model if the using MPICH version is less than the 4.2.0 version.
-------------------------------------------------------------------------------------------------------------
-Unfortunately, this version of MPICH has a problem with shared memory in the Controller/Worker model.
+MPICH versions less than 4.2.0 have an issue related to shared memory feature in Controller/Worker model.
 
 **Solution**
-You can run your script using the SPMD model, or use other MPI implementations 
-such as Open MPI, Intel MPI, or MPICH above version 4.2.0.
+
+You can run your script using MPICH in SPMD model, or use other MPI implementations 
+such as Open MPI, Intel MPI, or MPICH above 4.2.0.
+
+.. _`Open MPI's mpiexec`: https://www.open-mpi.org/doc/v3.1/man1/mpiexec.1.php
+.. _`issue`: https://github.com/modin-project/unidist/issues

unidist/core/backends/mpi/core/common.py

@@ -464,14 +464,16 @@ def versiontuple(v):
     return versiontuple(mpich_version) >= versiontuple(target_version)
 
 
-def is_shared_memory_supported(send_warning=False):
+def is_shared_memory_supported(raise_warning=False):
     """
     Check if the unidist on MPI supports shared memory.
 
     Parameters
     ----------
-    send_warning: bool, default: False
-        The need for warning as a flag.
+    raise_warning: bool, default: False
+        Whether to raise a warning or not.
+        ``True`` is passed only for root process
+        to have the only warning.
 
     Returns
     -------
@@ -486,9 +488,11 @@ def is_shared_memory_supported(send_warning=False):
         return False
 
     if MPI.VERSION < 3:
-        warnings.warn(
-            "The too old version of MPI is used. Shared object store can not be used."
-        )
+        if raise_warning:
+            warnings.warn(
+                f"Shared object store for MPI backend is not supported for MPI version {MPI.VERSION} "
+                "since it doesn't support shared memory feature."
+            )
         return False
 
     # Mpich shared memory does not work with spawned processes prior to version 4.2.0.
@@ -497,10 +501,11 @@ def is_shared_memory_supported(send_warning=False):
         and MpiSpawn.get()
         and not check_mpich_version("4.2.0")
     ):
-        warnings.warn(
-            "Shared object store is not supported in C/W model if the using MPICH version is less than the 4.2.0 version."
-            + "Please read more about this problem in the `Troubleshooting` chapter of the Unidist documentation."
-        )
+        if raise_warning:
+            warnings.warn(
+                "Shared object store for MPI backend is not supported in C/W model for MPICH version less than 4.2.0. "
+                + "Read more about this issue in the `troubleshooting` page of the unidist documentation."
+            )
         return False
 
     return True

unidist/core/backends/mpi/core/shared_object_store.py

@@ -107,9 +107,8 @@ def __init__(self):
         self.service_info_max_count = None
 
         mpi_state = communication.MPIState.get_instance()
-
         # Initialize all properties above
-        if common.is_shared_memory_supported(send_warning=mpi_state.is_root_process()):
+        if common.is_shared_memory_supported(raise_warning=mpi_state.is_root_process()):
             self._allocate_shared_memory()
 
         # Logger will be initialized after `communicator.MPIState`