python script keeps using 120% CPU

Question

I'm having an issue with my websocket script. Over time it consumes more and more CPU. One remedy I've discovered is to clear the associated logfile. This resolves the problem for a little while, but the CPU usuage builds up to 120% in little over a day or so. (using the top command on the linux server)

The part of the script that does the file write looks a bit odd to me. Here is the code:

 f = open(file, 'a')
 f.write(line+"\n")
 os.fsync(f.fileno())
 f.flush()
 f.close

I'm not a Python expert, but for starters, the last three things do rather the same in my opinion. The python manual states http://docs.python.org/2/library/os.html#os.fsync that f.flush and os.fsync should be in reverse order...

Can I just use:

 f = open(file, 'a')
 f.write(line+"\n")
 f.close

and should it not be: f.close()??

Any ideas?

You are never closing your file, yes it should be f.close() — jamylak
– jamylak, Commented May 2, 2013 at 12:20
You're right in that a close() implies a flush(), and I've no idea what fsync() is meant to accomplish if you're already working on a file object and not on the raw handles. — millimoose
– millimoose, Commented May 2, 2013 at 12:25

eumiro · Accepted Answer · 2013-05-02 12:21:29Z

4

Use this to open (and automatically close) your files:

with open(filename, 'a') as f:
    f.write(line+"\n")

answered May 2, 2013 at 12:21

eumiro

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1 Comment

Jeroen Over a year ago

Even with this modification, the script still eats CPU like mad. It is the correct answer, so I'll accept it.

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