来自文件的Python ElementTree.parse（）不会关闭该文件

Question

I have a xml file - kind of template to fill within the parameters and make a request (create some data).

I open this file with

tree = ET.parse(path_to_file)

and I make loop to get the xml from file, fill with the parameters and send a request. But after 2555 requests I get an error message:

IOError: [Errno 24] Too many open files: 'resources/cmr/skeletons/man/CreateLiveEvent.xml'

Is there a way to close file after ET.parse() opens it?

Thanks

Answer 1

Upgrade your 2.7 installation. This supposedly was fixed in issue #7334 , and was included in 2.7.3. It does look like there is a bug in the way the cElementTree implementation closes files however (eg it doesn't close them).

The alternative is to open the file yourself:

with open(path_to_file, 'rb') as xml_file:
    tree = ET.parse(xml_file)

and leave it to the with statement to close the file object. Open the file as binary ; it is the job of the XML parser to handle line endings and encodings.

Answer 2

You could open the file yourself and close it:

source = open(path_to_file)
tree = ET.parse(source)
... do your work ...
source.close()

Answer 3

This is not an answer but a possible solution or work-around.

I was working on a large xml file, 240 Meg, just parsing and searching with no other file activity just to measure the time to search the data. The script did not even print any info. I had just one print('Done.') as the last statement at the end. When my script was done Python printed the "Done." and then hung for awhile while Python took care GC cleanup. I then saw a noticeable Python exit speed-improvement when I did:

def search(elem):
    """Recursive"""
    # check for lots of elements

tree = ET.parse(source)
root = tree.getroot() # a large and deep element
search(root) # time it

print('Deleting tree')
del tree

# root still usable after del tree.
# You can still process the in-memory root
# at this point but I suspect not tree.write().
process(root)

print('Deleting root')
del root  # not necessary but seemed to improve exit
print('Done')

Perhaps del tree closes the file. I do not know if this is true. I used cPython. I do not know if this is implementation independent.