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Date: Thu, 6 Mar 2014 17:07:01 -0500
Subject: Re: script uses up all memory
From: Larry Martell <larry.martell@gmail.com>
To: "python-list@python.org" <python-list@python.org>
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On Thu, Mar 6, 2014 at 4:56 PM, Larry Martell <larry.martell@gmail.com> wrote:
> On Wed, Mar 5, 2014 at 5:27 PM, Larry Martell <larry.martell@gmail.com> wrote:
>> I have a script that forks off other processes and attempts to manage
>> them. Here is a stripped down version of the script:
>>
>>         self.sleepTime = 300
>>         self.procs = {}
>>         self.startTimes = {}
>>         self.cmd = ['python', '/usr/local/motor/motor/app/some_other_script.py']
>>
>>         while True:
>>             try:
>>                 self.tools = Tool.objects.filter(ip__isnull=False)
>>             except Exception, e:
>>                 print 'error from django call: ' + str(e)
>>                 sys.exit(1)
>>
>>             for tool in self.tools:
>>                 name = tool.name
>>                 if name in self.procs:
>>                     if self.procs[name].poll() is None:
>>                         if
>> (datetime.datetime.now()-self.startTimes[name]) >
>> datetime.timedelta(hours=12):
>>                             # it's been running too long - kill it
>>                             print 'killing script for ' + name + "
>> it's been running too long"
>>                             self.procs[name].kill()
>>                         else:
>>                             continue
>>
>>                     if self.procs[name].returncode:
>>                         print 'scrikpt failed for ' + name + ', error
>> = ' + str(self.procs[name].returncode)
>>
>>                     print 'starting script.py for ' + name + ' at ' +
>> str(datetime.datetime.now())
>>                     try:
>>                         self.procs[name] = subprocess.Popen(self.cmd)
>>                         self.startTimes[name] = datetime.datetime.now()
>>                     except Exception, e:
>>                         print 'error from Popen: ' + str(e)
>>                         sys.exit(1)
>>                 else:
>>                     print 'starting script.py for ' + name + ' at ' +
>> str(datetime.datetime.now())
>>                     try:
>>                         self.procs[name] = subprocess.Popen(self.cmd)
>>                         self.startTimes[name] = datetime.datetime.now()
>>                     except Exception, e:
>>                         print 'error from Popen: ' + str(e)
>>                         sys.exit(1)
>>
>>                 time.sleep(self.sleepTime)
>>
>>
>> The script does what it's intended to do, however after about 2 hours
>> it has used up all the memory available and the machine hangs. Can
>> anyone see something that I am doing here that would be using memory
>> like this? Perhaps some immutable object needs to be repeatedly
>> recreated?
>
> I figured out what is causing this. Each pass through the loop it does:
>
> self.tools = Tool.objects.filter(ip__isnull=False)
>
> And that is what is causing the memory consumption. If I move that
> outside the loop and just do that once the memory issue goes away. Now
> I need to figure out why this is happening and how to prevent it as
> they do want to query the db each pass through the loop in case it has
> been updated.

Apparently the object returned by that call is immutable as if I look
at id(self.tools) each pass through the loop, it is different. Is
there some way I can recover that memory?