code: def testBigMPI(self):
      comm = self.COMM
      size = comm.Get_size()
      rank = comm.Get_rank()
      dest = (rank + 1) % size
      source = (rank - 1) % size
      bigmpi = self.bigmpi
      blocksizes = (
          63,
          64,
          65,
          (1 << 12) - 1,
          (1 << 12),
          (1 << 12) + 1,
      )
      for blocksize in blocksizes:
          bigmpi.blocksize = blocksize
          a = numpy.empty(1024, dtype="i")
          b = numpy.empty(1024, dtype="i")
          c = numpy.empty(1024, dtype="i")
          a.fill(rank)
          b.fill(dest)
          c.fill(42)
          status = MPI.Status()
          smess = (a, b)
          rmess = comm.sendrecv(
              smess,
              dest,
              42,
              None,
              source,
              42,
              status,
          )
          self.assertTrue(numpy.all(rmess[0] == source))
          self.assertTrue(numpy.all(rmess[1] == rank))
          self.assertGreater(status.Get_elements(MPI.BYTE), 0)
          comm.barrier()
          status = MPI.Status()
          smess = (a, b)
          request = comm.issend(smess, dest, 123)
          rmess = comm.mprobe(source, 123).irecv().wait(status)
          self.assertTrue(numpy.all(rmess[0] == source))
          self.assertTrue(numpy.all(rmess[1] == rank))
          self.assertGreater(status.Get_elements(MPI.BYTE), 0)
          request.Free()
          comm.barrier()
          check = lambda x: numpy.all(x == 42)
          self.testBcastIntra([c, c], check)
          self.testBcastInter([c, c], check)
          check2 = lambda x: check(x[0]) and check(x[1])
          self.testBcastIntra([(c, c.copy())], check2)
          self.testBcastInter([(c, c.copy())], check2)
  
imports: from mpi4py import MPI
  from mpi4py.util import pkl5
  import sys, os
label_desc: Use image node_id 34 for calling the BaseTest obj's underlying member method code with example usage: obj.testBigMPI() without return types