Matplotlib 和 mpi4py：Tclerror：没有显示名称，也没有 $DISPLAY

Question

根据 ngoldbaum 的建议，我在此处发布了以前 Python 脚本的可运行示例。最后，我想让 root 执行一个绘图（来自调用 matplotlib 的包 scitools），但它遇到错误并且不产生任何输出。

import matplotlib
matplotlib.use('Agg')
import sys
import numpy as np
import yt
from scitools.all import *
from scitools.std import *
from matplotlib import rc
from mpi4py import MPI

yt.enable_parallelism()


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

print "rank, nprocs", rank, nprocs

# 
out_tmax = []
out_zmax = []
n_el = np.zeros(nprocs, dtype=int)

xmin = 0.
xmax = 2.2
deltax = (xmax - xmin)/nprocs

xmin_loc = xmin + rank*deltax
xmax_loc = xmin_loc + deltax

n_el[rank] = 10*(1 + rank)
if rank == 0:
    out_tmax = np.linspace(xmin_loc,xmax_loc,n_el[rank])
    out_zmax = sin(out_tmax)
    print "ok", out_tmax, out_zmax

# Plot
if yt.is_root():
#if rank == 0:
    rc('font',**{'family':'serif','serif':['Times']})
## for Palatino and other serif fonts use:
#    rc('font',**{'family':'serif','serif':['Palatino']})
    rc('text', usetex=True)
    rc('legend',fontsize=12)
    rc('axes',labelsize=14, titlesize=18)
    rc('xtick', labelsize=14)
    rc('ytick', labelsize=14)
    plot(out_tmax, out_zmax, 'b', fontname='Times new Roman', xlabel=(r'Time (Myr)'), ylabel=(r'\mathrm{z_{HS}}'), hardcopy='fig1.png')

看起来根进程没有继承开始时所做的“use: Agg”选择（我没有得到 plot() 中指定的任何 *png 输出。我使用 s 脚本将其提交给 PBS 批处理系统：

#!/bin/bash
## Name of the job
#PBS -N test_mpi4py_matlib

#PBS -l select=1:ncpus=4:mpiprocs=4:mem=24gb
#PBS -l place=scatter

#PBS -e test_gatherv_print.err
#PBS -o test_gatherv_print.out
#PBS -l walltime=00:20:00
....
mpirun python2.7 test_gatherv_print.py

此脚本的前两行应防止 plot（基于 matplotlib）查找 DISPLAY 环境变量。

此脚本失败并出现以下错误：

  File "test_gatherv_print.py", line 49, in <module>
    plot(out_tmax, out_zmax, 'b', fontname='Times new Roman', xlabel=(r'Time (Myr)'), ylabel=(r'\mathrm{z_{H
S}}'), hardcopy='fig1.png')
  File "/home/van/software/python/scitools/lib/python2.7/site-packages/scitools/easyviz/common.py", line 313
9, in plot
    self.setp(**kwargs)
  File "/home/van/software/python/scitools/lib/python2.7/site-packages/scitools/easyviz/common.py", line 194
1, in setp
    self.hardcopy(kwargs['hardcopy'])
  File "/home/van/software/python/scitools/lib/python2.7/site-packages/scitools/easyviz/matplotlib_.py", lin
e 1065, in hardcopy
    self._replot()
  File "/home/van/software/python/scitools/lib/python2.7/site-packages/scitools/easyviz/matplotlib_.py", lin
e 944, in _replot
    self._g.figure(self.getp('curfig'))
  File "/opt/Python-2.7.9/lib/python2.7/site-packages/matplotlib/pyplot.py", line 533, in figure
    **kwargs)
  File "/opt/Python-2.7.9/lib/python2.7/site-packages/matplotlib/backend_bases.py", line 161, in new_figure_
manager
    return cls.new_figure_manager_given_figure(num, fig)
  File "/opt/Python-2.7.9/lib/python2.7/site-packages/matplotlib/backends/_backend_tk.py", line 1046, in new
_figure_manager_given_figure
    window = Tk.Tk(className="matplotlib")
  File "/opt/Python-2.7.9/lib/python2.7/lib-tk/Tkinter.py", line 1810, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
P000 yt : [ERROR    ] 2020-05-13 16:28:32,964 TclError: no display name and no $DISPLAY environment variable
P000 yt : [ERROR    ] 2020-05-13 16:28:32,965 Error occured on rank 0.

虽然我在上面的 matplotlib.use() 中指定了“Agg”输出。

Answer 1

感谢您的建议。我已经尝试了您的所有建议：1）在本地目录和.config下都配置了matplotlibrc（后端：Agg）； 2) 使用 matplotlib 命令而不是 scitools 中的“绘图”。关于后者，它是由 P. Langtangen 开发的实用程序包；特别是我在这里使用了 easyviz 子包（参见：https://hplgit.github.io/scitools/doc/api/html/easyviz.html）。但是，即使我不使用 scitools.easyviz 而是直接使用 matplotlib，我也无法从 MPI 生成的根进程中生成 .png 输出。我在最后替换了以下几行：

...
    plt.plot(out_tmax, out_zmax)
    plt.savefig('fig1.png')

现在我收到以下错误：

P000 yt : [ERROR    ] 2020-05-14 10:32:14,200 OSError: [Errno 2] No such file or directory: 'latex'
P000 yt : [ERROR    ] 2020-05-14 10:32:14,200 Error occured on rank 0.

请注意，当我以交互方式运行脚本时，它会正确生成 fig1.png 输出。 如您所见，问题现在已经转移：root 不读取某些环境变量。请注意，我将作业提交给 PBS 批处理系统。最后一个脚本是这样的：

#!/bin/tcsh
## Name of the job
#PBS -N test_mpi4py_matlib

## Number of nodes (in this case I require 8 nodes with 1 CPU each)
## The total number of nodes passed to mpirun will be nodes*ppn 
##PBS -l nodes=5:ppn=16
##PBS -l nodes=2:ppn=8
#PBS -l select=1:ncpus=4:mpiprocs=4:mem=24gb
#PBS -l place=scatter
#PBS -V 
# inherits all environment variables, including DISPLAY

#! Name of output files for std output and error;
#! if non specified defaults are <job-name>.o<job number> and <job-name>.e<job-number>
#
#PBS -e test_gatherv_print.err
#PBS -o test_gatherv_print.out
#PBS -l walltime=00:20:00
##PBS -q high


#comandi
#printenv LD_LIBRARY_PATH
printenv DISPLAY

cd /home/van/projects/jet_ism/turbulence/python

date
#echo 'Hello world'
/opt/openmpi_icc/bin/mpirun python2.7 test_gatherv_print.py

这里我使用 tcsh，但在我使用 ksh 之前。