使用mpi4py創建子數組數據類型

Question

我正在製作一個簡單的程序，我試圖使用mpi4py從8x8矩陣發送4 x 4矩陣子矩陣。我的方法是使用子數組數據類型，但我不斷收到分段錯誤。

我的代碼如下：

import numpy as np 
from mpi4py import MPI 

comm = MPI.COMM_WORLD 
rank = comm.Get_rank() 

sizes = (8,8) # Matrix dimensions 
subsizes = (4,4) # Sub-matrix dimensions 
displs = (0, 4, 32, 36) 

counts = (1, 1, 1, 1) 
starts = (0,0) 

mynum = counts[rank] 
glob = np.empty((8,8), dtype = 'f') 
local = np.empty((4,4), dtype = 'f') 

if rank == 0: # Fill each quadrant with 0-3 

    for row in range(0,4): 
     for col in range(0,4): 
      glob[row, col] = 0 
    for row in range(0,4): 
     for col in range(4,8): 
      glob[row, col] = 1 
    for row in range(4,8): 
     for col in range(0,4): 
      glob[row, col] = 2 
    for row in range(4,8): 
     for col in range(4,8): 
      glob[row, col] = 3 
    print glob 

submatrixType = MPI.DOUBLE.Create_subarray(sizes, subsizes, starts, order = MPI.ORDER_C) 
submatrixType.Commit() 

sendbuf = [glob, counts, displs, submatrixType] 
recvbuf = [local, 16, MPI.DOUBLE] 

comm.Scatterv(sendbuf, recvbuf, root = 0) 
# or use 
#comm.Scatterv(sendbuf, recvbuf, MPI.DOUBLE) 

print rank, " " ,local 

我的結果與4個進程運行時，如下：

Proc 0: [[0. 0. 0. 0.] 
[1. 1. 1. 1.] 
[0. 0. 0. 0.] 
[1. 1. 1. 1.]] 

Traceback (most recent call last): 
Traceback (most recent call last): 
    File "main.py", line 41, in <module> 
     File "main.py", line 41, in <module> 
    comm.Scatterv(sendbuf, local, root = 0) 
comm.Scatterv(sendbuf, local, root = 0) 
    File "Comm.pyx", line 454, in mpi4py.MPI.Comm.Scatterv (src/mpi4py.MPI.c:67458) 
    File "Comm.pyx", line 454, in mpi4py.MPI.Comm.Scatterv (src/mpi4py.MPI.c:67458) 
mpi4py.MPImpi4py.MPI.Exception: .Exception: MPI_ERR_TRUNCATE: message truncated 
MPI_ERR_TRUNCATE: message truncated 
Traceback (most recent call last): 
    File "main.py", line 41, in <module> 
    comm.Scatterv(sendbuf, local, root = 0) 
    File "Comm.pyx", line 454, in mpi4py.MPI.Comm.Scatterv (src/mpi4py.MPI.c:67458) 
mpi4py.MPI.Exception: MPI_ERR_TRUNCATE: message truncated 

我有關於Create_subarray錯誤的想法或有什麼可以否則會出錯？

Answer 1

問題在於你的「位移」。你已經正確地描述了一個具有'sizes'，'subsizes'和'starts'的子類型，但是當你取代這個類型時，你已經將類型描述從實際的2d數組的末尾移開了。

移居其他類型通常不是問題，但是對於子數組，您有這個「原始數組」的概念會給出問題。

我做了VECTOR的快速替換，但我仍然有內存損壞。