Concurrent writes to the same file
Neal Becker
ndbecker2 at gmail.com
Thu Jul 11 11:58:57 EDT 2013
Dave Angel wrote:
> On 07/11/2013 12:57 AM, Jason Friedman wrote:
>> Other than using a database, what are my options for allowing two processes
>> to edit the same file at the same time? When I say same time, I can accept
>> delays. I considered lock files, but I cannot conceive of how I avoid race
>> conditions.
>>
>
> In general, no. That's what a database is for.
>
> Now, you presumably have some reason to avoid database, but in its stead
> you have to specify some other limitations. To start with, what do you
> mean by "the same time"? If each process can modify the entire file,
> then there's no point in one process reading the file at all until it
> has the lock. So the mechanism would be
> 1) wait till you can acquire the lock
> 2) open the file, read it, modify it, flush and close
> 3) release the lock
>
> To come up with an appropriate lock, it'd be nice to start by specifying
> the entire environment. Which Python, which OS? Are the two processes
> on the same CPU, what's the file system, and is it locally mounted?
>
>
>
>
You can use a seperate server process to do file I/O, taking multiple inputs
from clients. Like syslogd.
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