Avoid program exit when input / output error

Question

I have a Python script using shutil.copy2. Since I use it to copy files over the network, I get input / output errors too frequent, which leads to an abortion of my program execution:

Traceback (most recent call last):
  File "run_model.py", line 46, in <module>
    main()
  File "run_model.py", line 41, in main
    tracerconfigfile=OPT.tracerconfig)
  File "ModelRun.py", line 517, in run
    self.copy_data()
  File "ModelRun.py", line 604, in copy_ecmwf_data
    shutil.copy2(remotefilename, localfilename)
  File "/usr/lib64/python2.6/shutil.py", line 99, in copy2
    copyfile(src, dst)
  File "/usr/lib64/python2.6/shutil.py", line 54, in copyfile
    copyfileobj(fsrc, fdst)
  File "/usr/lib64/python2.6/shutil.py", line 27, in copyfileobj
    buf = fsrc.read(length)
IOError: [Errno 5] Input/output error

How can I avoid abortions of my program execution and retry the copy process?

The code I'm using already checks if the file is really fully copied by checking the file size:

def check_file(file, size=0):
    if not os.path.exists(file):
        return False
    if (size != 0 and os.path.getsize(file) != size):
        return False
    return True

while (check_file(rempdg,self._ndays*130160640) is False):
    shutil.copy2(locpdg, rempdg)

Answer 1

Which block gives an error? Just wrap try / except around it:

def check_file(file, size=0):
    try:
        if not os.path.exists(file):
            return False
        if (size != 0 and os.path.getsize(file) != size):
            return False
        return True
    except IOError:
        return False # or True, whatever your default is

while (check_file(rempdg,self._ndays*130160640) is False):
    try:
        shutil.copy2(locpdg, rempdg)
    except IOError:
        pass # ignore the IOError and keep going

Answer 2

you can use

try:
    ...
except IOError as err:
    ...

to catch errors and handle them

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