我不太熟悉在 Python 中创建守护进程的方式，因此当我尝试安装和运行第三方开源 TeX Python Wrapper 时，我被一个我不理解的错误所困扰。
我添加了一些打印来帮助调试。
错误的称为 texdp.py
当我运行调用 texdp 服务器启动的 mathrand 时，出现以下错误
output_fds {8: 'dvi', 5: 'log', 6: 'logfile', 7: 'err'}
input_fds 3
readable, writable [] [3] outflds, inputflds: [8, 5, 6, 7] [3]
pointer len_str: 0 63
folder fd: 7
readable, writable [5] [] outflds, inputflds: [8, 5, 6, 7] []
pointer len_str: 63 63
folder fd: 7
readable, writable [5] [] outflds, inputflds: [8, 5, 6, 7] []
pointer len_str: 63 63
folder fd: 5
readable, writable [] [] outflds, inputflds: [8, 5, 6, 7] []
pointer len_str: 63 63
folder fd: 5
SUB IO ERROR: readable [] pointer == len_str: 63 , 63
Traceback (most recent call last):
File "/usr/local/bin/mathtrand", line 18, in <module>
server.start()
File "/usr/local/lib/python2.6/dist-packages/mathtran/server.py", line 71, in start
self.secplain.start()
File "/usr/local/lib/python2.6/dist-packages/tex/texdp.py", line 159, in start
self.process(self._params.start)
File "/usr/local/lib/python2.6/dist-packages/tex/texdp.py", line 175, in process
value = self._process(str + self._params.done, self._params.done_str)
File "/usr/local/lib/python2.6/dist-packages/tex/texdp.py", line 210, in _process
raise SubprocessError, 'subprocess I/O timed out'
负责的代码部分附加并位于方法def _process中的第 200 行附近。
我不知道从哪里开始寻找，以及这个错误的真正含义。任何帮助都非常受欢迎。
https://texd.svn.sourceforge.net/svnroot/texd/trunk/py/tex/texdp.py
# Copyright: (c) 2007 The Open University, Milton Keynes, UK
# License: GPL version 2 or (at your option) any later version.
# Author: Jonathan Fine <jfine@pytex.org>, <J.Fine@open.ac.uk>
"""Wrapper around TeX process, to handle input and output.
Further comments to go here.
"""
__version__ = '$Revision: 116 $'[11:-2]
# $Source$
# TODO: Move interface instances to elsewhere.
# TODO: error recovery, e.g. undefined control sequence.
# TODO: Abnormal exit is leaving orphaned processes.
# TODO: Refactor _process into tex.util, share with metapostdp.
import os # Create directories and fifos
from select import select # Helps handle i/o to TeX process
from tex.util import make_nonblocking # For non-blocking file descriptor
from tex.util import DaemonSubprocess
from tex.dviopcode import FNT_DEF1, FNT_DEF4
import signal
class SubprocessError(EnvironmentError):
pass
# TODO: This belongs elsewhere.
class Interface(object):
"""Stores useful, but format specific, constants."""
def __init__(self, **kwargs):
# TODO: Be more specific about the parameters.
self.__dict__ = kwargs
# TeX knows about these fonts, but Python does not yet know.
# This list created by command: $tex --ini '&plain' \\dump
preloaded_fonts = ( 'cmr10', 'cmr9', 'cmr8', 'cmr7', 'cmr6', 'cmr5',
'cmmi10', 'cmmi9', 'cmmi8', 'cmmi7', 'cmmi6',
'cmmi5', 'cmsy10', 'cmsy9', 'cmsy8', 'cmsy7',
'cmsy6', 'cmsy5', 'cmex10', 'cmss10', 'cmssq8',
'cmssi10', 'cmssqi8', 'cmbx10', 'cmbx9', 'cmbx8',
'cmbx7', 'cmbx6', 'cmbx5', 'cmtt10', 'cmtt9',
'cmtt8', 'cmsltt10', 'cmsl10', 'cmsl9', 'cmsl8',
'cmti10', 'cmti9', 'cmti8', 'cmti7', 'cmu10',
'cmmib10', 'cmbsy10', 'cmcsc10', 'cmssbx10',
'cmdunh10', 'cmr7 scaled 2074',
'cmtt10 scaled 1440', 'cmssbx10 scaled 1440',
'manfnt', )
# Ship out a page that starts with a font def.
load_font_template = \
r'''%%
\begingroup
\hoffset 0sp
\voffset 0sp
\setbox0\hbox{\font\tmp %s\relax\tmp M}%%
\ht0 0sp
\shipout\box 0
\endgroup
'''
secplain_load_font_template = \
r'''%%
\_begingroup
\_hoffset 0sp
\_voffset 0sp
\_setbox0\_hbox{\_font\_tmp %s\_relax\_tmp M}%%
\_ht0 0sp
\_shipout\_box 0
\_endgroup
'''
plain = Interface(format='plain',
start = r'\shipout\hbox{}' '\n',
done = '\n' r'\immediate\write16{DONE}\read-1to\temp ' '\n',
done_str = 'DONE\n',
stop = '\end' '\n',
preloaded_fonts = preloaded_fonts,
load_font_template = load_font_template,
)
secplain = Interface(format='secplain',
start = r'\_shipout\_hbox{}' '\n',
done = '\n' r'\_immediate\_write16{DONE}\_read-1to\_temp ' '\n',
done_str = 'DONE\n',
stop = '\_end' '\n',
preloaded_fonts = preloaded_fonts,
load_font_template = secplain_load_font_template,
)
class Texdp(DaemonSubprocess):
"""Wrapper around TeX process that handles input and output.
More comments go here.
"""
_fifos = ('texput.tex', 'texput.log', 'texput.dvi')
def _make_args(self):
# Don Knuth created plain.fmt, renamed by some to tex.fmt.
fmt = self._params.format
if fmt == 'plain' or fmt == 'tex':
fmt = ''
else:
fmt = '--fmt=' + fmt
# Build up the arguments list.
args = ('tex', '--ipc',)
args += ('--output-comment=""',) # Don't record time of run.
if fmt:
args += (fmt,)
args += ('texput.tex',)
return args
def start(self):
super(Texdp, self).start() # Start the TeX process.
# We will now initialise TeX, and conprocessnect to file descriptors.
# We need to do some low-level input/output, in order to
# manage long input strings. Therefore, we use file
# descriptors rather than file objects.
# We map output fds to what will be a dictionary key.
ofd = self._output_fd_dict = {}
cwd = self._cwd # Shorthand.
child = self._child
# For us, stdin and stdout are special.
self._stdin = child.stdin.fileno()
self._stdout = child.stdout.fileno()
# Read stdout and stderr to 'log' and 'err' respectively.
ofd[self._stdout] = 'log'
ofd[child.stderr.fileno()] = 'err'
# Open 'texput.tex', and block until it is available, which is
# when TeX has started. Then make 'texput.tex' non-blocking,
# in case of a long write.
self._texin = os.open(os.path.join(cwd, 'texput.tex'), os.O_WRONLY)
make_nonblocking(self._texin)
# Read 'texput.log' and 'texput.dvi' to 'logfile' and 'dvi'.
for src, tgt in (('texput.log', 'logfile'), ('texput.dvi', 'dvi')):
fd = os.open(os.path.join(cwd, src),
os.O_RDONLY|os.O_NONBLOCK)
ofd[fd] = tgt
# Ship out blank page, and initialise preloaded fonts.
self.process(self._params.start)
self._fontdefs = []
for font_spec in self._params.preloaded_fonts:
self.load_new_font(font_spec)
def process(self, str):
"Return dictionary with log, dvi, logfile and err entries."
# TeX will read the data, following by the 'done' command.
# The 'done' command will cause TeX to write the 'done_str',
# which signals the end of the process. It will also pause
# TeX for input.
# TODO: I do not know why the pause is required, but it is.
# Remove it here and in the _params, and the program hangs.
value = self._process(str + self._params.done, self._params.done_str)
self._child.stdin.write('\n') # TeX is paused for input.
return value
def _process(self, str, done_str):
# Write str, and read output, until we are done. Then gather
# up the accumulated output, and return as a dictionary. The
# input string might be long. Later, we might allow writing to
# stdin, in response to errors.
# Initialisation.
print "output_fds ", self._output_fd_dict
output_fds = self._output_fd_dict.keys()
print "input_fds ", self._texin
input_fds = [self._texin]
accumulator = {}
for fd in output_fds:
accumulator[fd] = []
pointer, len_str = 0, len(str)
# The main input/ouput loop.
# TOD0: magic number, timeout.
done = False
while not done:
readable, writable = select(output_fds, input_fds, [], 0.1)[0:2]
print "readable, writable", readable, writable, " outflds, inputflds: ", output_fds, input_fds
print "pointer len_str: ", pointer, len_str
print "folder fd: ", fd
if not readable and pointer == len_str:
print "SUB IO ERROR: readable", readable, " pointer == len_str:", pointer, ",", len_str
os.kill(self._child.pid, signal.SIGKILL)
self._child.wait()
raise SubprocessError, 'subprocess I/O timed out'
if pointer != len_str and writable:
written = os.write(self._texin, str[pointer:pointer+4096])
pointer += written
if pointer == len_str:
input_fds = []
for fd in readable:
if self._child.poll() is not None:
raise SubprocessError, 'read from terminated subprocess'
tmp = os.read(fd, 4096)
if fd == self._stdout:
if tmp.endswith(done_str):
tmp = tmp[:-len(done_str)]
done = True
accumulator[fd].append(tmp)
if pointer != len_str:
raise SystemError, "TeX said 'done' before end of input."
# Join accumulated output, create and return ouput dictionary.
value = {}
for fd, name in self._output_fd_dict.items():
value[name] = ''.join(accumulator[fd])
return value
def load_new_font(self, font_spec):
"""Tell both TeX and Python about a new font.
Raises an exception if the font is not new.
"""
# Ask TeX to load font, and ship out page that uses it.
command mathtran= self._params.load_font_template % font_spec
dvi = self.process(command)['dvi']
bytes = dvi[45:-1] # Page body.
opcode = ord(bytes[0]) # First opcode.
# The first opcode should be a fontdef, which we extract.
if FNT_DEF1 <= opcode <= FNT_DEF4:
body_len = (2 + (opcode - FNT_DEF1)
+ 12 # Checksum, scale, design size.
+ 2) # Length of 'area' and font name.
name_len = ord(bytes[body_len - 2]) \
+ ord(bytes[body_len - 1])
fontdef = bytes[:body_len + name_len]
self._fontdefs.append(fontdef)
return
else:
raise ValueError, "font '%s' not new or not found" % font_spec