Lockfile hanling

[Christian Gollwitzer]

Am 31.03.15 um 21:17 schrieb Ian Kelly:
> On Tue, Mar 31, 2015 at 12:58 PM, Christian Gollwitzer <auriocus at gmx.de> wrote:
>> Am 31.03.15 um 16:50 schrieb Ervin Hegedüs:
>>>
>>> there is an app, written in Python, which stores few bytes of
>>> datas in a single file. The application uses threads. Every
>>> thread can modify the file, but only one at a time. I'm using a
>>> lock file to prevent the multiple access.
>>>
>>> Here is the lock method:
>>>
>>> [...]
>>> This works as well for me - about 3-4 weeks. After some weeks, I
>>> got this error:
>>>
>>> OSError: [Errno 24] Too many open files: '/var/spool/myapp/queue.lock'
>>>
>>
>> Can you try if fcntl.flock() does what you want? Should be better than
>> inventing your own locking mechanism.
>
> flock locks are per-process; they won't help for synchronizing access
> between competing threads in the same process.
>

Ok. But if it is really all in one process, then a classical mutex would 
do, wouldn't it? I'm not experienced with threading in Python, but it 
seems from the documentation, that threading.Lock() works like a mutex.

	Christian