MPI（mpi4py）的python问题，客户端无法连接

Question

我得到的错误是：

Traceback（最近一次调用最后一次）： 文件“client2.py”，第 14 行，在 端口 = MPI.Lookup_name（服务，信息） 文件“Comm.pyx”，第 1676 行，位于 mpi4py.MPI.Lookup_name (src/mpi4py.MPI.c:64562) mpi4py.MPI.Exception: MPI_ERR_NAME: 无效的名称参数

我正在尝试使用 mpi4py 实现客户端/服务器模型。服务器可以 Publish_name 并等待客户端。但是，客户端不能使用api中描述的必要方法，如下所示：

#! /usr/bin/env python

from mpi4py import MPI

rank = MPI.COMM_WORLD.Get_rank()

def log(msg, *args):
    if rank == 0:
        print msg % args

info = MPI.INFO_NULL
service = 'pyeval'
log("looking-up service '%s'", service)
port = MPI.Lookup_name(service, info) // PROBLEM HERE !
log("service located  at port '%s'", port)

root = 0
log('waiting for server connection...')
comm = MPI.COMM_WORLD.Connect(port, info, root)
log('server connected...')

while True:
    done = False
    if rank == root:
        try:
            message = raw_input('pyeval>>> ')
            if message == 'quit':
                message = None
                done = True
        except EOFError:
            message = None
            done = True
        comm.Send(message, dest=0, tag=0)
   else:
        message = None
    done = MPI.COMM_WORLD.Bcast(done, root)
    if done:
        break

log('disconnecting server...')
comm.Disconnect()

我还发布了服务器端代码，因为它可能会有所帮助：

#! /usr/bin/env python

from mpi4py import MPI

rank = MPI.COMM_WORLD.Get_rank()

def log(msg, *args):
    if rank == 0:
        print msg % args


log('')

info = MPI.INFO_NULL

port = MPI.Open_port(info)
log("opened port: '%s'", port)

service = 'pyeval'
MPI.Publish_name(service, info, port)
log("published service: '%s'", service)

root = 0
log('waiting for client connection...')
comm = MPI.COMM_WORLD.Accept(port, info, root)
log('client connected...')

while True:
    done = False
    if rank == root:
        message = comm.Recv(source=0, tag=0)
        if message is None:
            done = True
        else:
            try:
                print 'eval(%r) -> %r' % (message, eval(message))
            except StandardError:
                print "invalid expression: %s" % message
    done = MPI.COMM_WORLD.Bcast(done, root)
    if done:
        break

log('disconnecting client...')
comm.Disconnect()

log('upublishing service...')
MPI.Unpublish_name(service, info, port)

log('closing port...')
MPI.Close_port(port)

Answer 1

您希望服务器生成客户端以便它们可以通信。此外，您的 Send/Recv/Bcasts 应该是 send/recv/bcast ； mpi4py 支持 Send 和 send、Recv 和 recv 等，但大写版本采用“常规”C/C++/Fortran 参数，而小写版本则更 Pythonic。

因此，我成功运行了以下内容 - client.py：

#! /usr/bin/env python
from mpi4py import MPI

rank = MPI.COMM_WORLD.Get_rank()

def log(msg, *args):
    if rank == 0:
        print msg % args

info = MPI.INFO_NULL
service = "pyeval"
log("looking-up service '%s'", service)
port = MPI.Lookup_name(service)
log("service located  at port '%s'", port)

root = 0
log('waiting for server connection...')
comm = MPI.COMM_WORLD.Connect(port, info, root)
log('server connected...')

while True:
    done = False
    if rank == root:
        try:
            message = raw_input('pyeval>>> ')
            if message == 'quit':
                message = None
                done = True
        except EOFError:
            message = None
            done = True
        comm.send(message, dest=0, tag=0)
    else:
        message = None
    done = MPI.COMM_WORLD.bcast(done, root)
    if done:
        break

log('disconnecting server...')
comm.Disconnect()

和 server.py：

#! /usr/bin/env python

from mpi4py import MPI

rank = MPI.COMM_WORLD.Get_rank()

def log(msg, *args):
    if rank == 0:
        print msg % args

log('')

info = MPI.INFO_NULL

port = MPI.Open_port(info)
log("opened port: '%s'", port)

service = 'pyeval'
MPI.Publish_name(service, info, port)
log("published service: '%s'", service)

MPI.COMM_WORLD.Spawn("./client.py", maxprocs=1)

root = 0
log('waiting for client connection...')
comm = MPI.COMM_WORLD.Accept(port, info, root)
log('client connected...')

while True:
    done = False
    if rank == root:
        message = comm.recv(source=0, tag=0)
        if message is None:
            done = True
        else:
            try:
                print 'eval(%r) -> %r' % (message, eval(message))
            except StandardError:
                print "invalid expression: %s" % message
    done = MPI.COMM_WORLD.bcast(done, root)
    if done:
        break

log('disconnecting client...')
comm.Disconnect()

log('upublishing service...')
MPI.Unpublish_name(service, info, port)

log('closing port...')
MPI.Close_port(port)

但是在这里您还必须处理这样一个事实，即大多数 MPI 实现只会将标准输入设为 0，因此客户端没有从终端获取输入的好方法（一般来说，这将如何如果有多个客户，工作？）

Answer 2

我需要使用 ompi-server 进行名称发布和名称查找。以下执行服务器和客户端的步骤对我有用：

ompi-服务器

rm -f /tmp/ompi-server.txt
killall ompi-server
ompi-server -r /tmp/ompi-server.txt

服务器

mpiexec --ompi-server file:/tmp/ompi-server.txt -n 1 python server.py

客户

mpiexec --ompi-server file:/tmp/ompi-server.txt -n 1 python client.py