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discuss in more detail MPI support in PyLammps. Some small improvements in MPI support

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MPI related changes are:
 - Raise exception in PyLammps.eval() if called from MPI rank
 - Print (some) informational and warning messages only from MPI rank 0
This commit is contained in:
Axel Kohlmeyer
2024-07-30 11:27:31 -04:00
parent a5a0620dca
commit 75b09ed143
3 changed files with 56 additions and 24 deletions
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23
python/lammps/pylammps.py
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@ -463,13 +463,19 @@ class PyLammps(object):
self.lmp = lammps(name=name,cmdargs=cmdargs,ptr=ptr,comm=comm)
else:
self.lmp = lammps(name=name,cmdargs=cmdargs,ptr=None,comm=comm)
print("LAMMPS output is captured by PyLammps wrapper")
self.comm_nprocs = self.lmp.extract_setting("world_size")
self.comm_me = self.lmp.extract_setting("world_rank")
if self.comm_me == 0:
print("LAMMPS output is captured by PyLammps wrapper")
if self.comm_nprocs > 1:
print("WARNING: Using PyLammps with multiple MPI ranks is experimental. Not all functionality is supported.")
self._cmd_history = []
self._enable_cmd_history = False
self.runs = []
if not self.lmp.has_package("PYTHON"):
print("WARNING: run thermo data not captured since PYTHON LAMMPS package is not enabled")
if self.comm_me == 0:
print("WARNING: run thermo data not captured since PYTHON LAMMPS package is not enabled")
def __enter__(self):
return self
@ -727,7 +733,15 @@ class PyLammps(object):
def eval(self, expr):
"""
Evaluate expression
Evaluate LAMMPS input file expression.
This is equivalent to using immediate variable expressions in the format "$(...)"
in the LAMMPS input and will return the result of that expression.
.. warning::
This function is only supported on MPI rank 0. Calling it from a different
MPI rank will raise an exception.
:param expr: the expression string that should be evaluated inside of LAMMPS
:type expr: string
@ -735,6 +749,9 @@ class PyLammps(object):
:return: the value of the evaluated expression
:rtype: float if numeric, string otherwise
"""
if self.comm_me > 0:
raise Exception("PyLammps.eval() may only be used on MPI rank 0")
value = self.lmp_print('"$(%s)"' % expr).strip()
try:
return float(value)