PERF: delay rarely used imports in yt.utilities

yt/utilities/parallel_tools/parallel_analysis_interface.py

@@ -10,9 +10,7 @@
 import numpy as np
 from more_itertools import always_iterable
 
-import yt.utilities.logger
 from yt.config import ytcfg
-from yt.data_objects.image_array import ImageArray
 from yt.funcs import is_sequence
 from yt.units.unit_registry import UnitRegistry  # type: ignore
 from yt.units.yt_array import YTArray
@@ -63,7 +61,7 @@ def write_to_file(exc_type, exc, tb):
 def default_mpi_excepthook(exception_type, exception_value, tb):
     traceback.print_tb(tb)
     mylog.error("%s: %s", exception_type.__name__, exception_value)
-    comm = yt.communication_system.communicators[-1]
+    comm = communication_system.communicators[-1]
     if comm.size > 1:
         mylog.error("Error occurred on rank %d.", comm.rank)
     MPI.COMM_WORLD.Abort(1)
@@ -90,6 +88,8 @@ def enable_parallelism(suppress_logging: bool = False, communicator=None) -> boo
     parallel_capable: bool
         True if the call was successful. False otherwise.
     """
+    import yt.utilities.logger
+
     global parallel_capable, MPI
     try:
         from mpi4py import MPI as _MPI
@@ -828,6 +828,8 @@ def par_combine_object(self, data, op, datatype=None):
 
     @parallel_passthrough
     def mpi_bcast(self, data, root=0):
+        from yt.data_objects.image_array import ImageArray
+
         # The second check below makes sure that we know how to communicate
         # this type of array. Otherwise, we'll pickle it.
         if isinstance(data, np.ndarray) and get_mpi_type(data.dtype) is not None:
@@ -1076,6 +1078,8 @@ def merge_quadtree_buffers(self, qt, merge_style):
         return qt
 
     def send_array(self, arr, dest, tag=0):
+        from yt.data_objects.image_array import ImageArray
+
         if not isinstance(arr, np.ndarray):
             self.comm.send((None, None), dest=dest, tag=tag)
             self.comm.send(arr, dest=dest, tag=tag)
@@ -1095,6 +1099,8 @@ def send_array(self, arr, dest, tag=0):
         del tmp
 
     def recv_array(self, source, tag=0):
+        from yt.data_objects.image_array import ImageArray
+
         metadata = self.comm.recv(source=source, tag=tag)
         dt, ne = metadata[:2]
         if ne is None and dt is None:
@@ -1111,6 +1117,8 @@ def recv_array(self, source, tag=0):
         return arr
 
     def alltoallv_array(self, send, total_size, offsets, sizes):
+        from yt.data_objects.image_array import ImageArray
+
         if len(send.shape) > 1:
             recv = []
             for i in range(send.shape[0]):

yt/utilities/parameter_file_storage.py

@@ -1,4 +1,3 @@
-import csv
 import os.path
 from itertools import islice
 
@@ -170,6 +169,8 @@ def get_recent(self, n=10):
 
     @parallel_simple_proxy
     def _write_out(self):
+        import csv
+
         if self._read_only:
             return
         fn = self._get_db_name()
@@ -187,6 +188,8 @@ def _write_out(self):
     @parallel_simple_proxy
     def read_db(self):
         """This will read the storage device from disk."""
+        import csv
+
         f = open(self._get_db_name())
         vals = csv.DictReader(f, _field_names)
         db = {}