Re: Using fcntl.flock with gevent

[vitaly]

On Thursday, February 7, 2013 1:17:43 AM UTC-8, Sebastien Estienne wrote:

How to make fcntl.flock to cooperate with gevent?

One way is to leverage a thread-pool in a similar way to how gevent 1.x uses a thread pools for some blocking I/O operations.

[Damien Churchill]

On 7 February 2013 09:17, Sebastien Estienne

<sebastien...@gmail.com> wrote:
> How to make fcntl.flock to cooperate with gevent?

You could use fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB) which
would raise an exception. You could then wrap this in a while loop if
you wanted to replicate the blocking behaviour using something along
the lines of:

while True:
try:
fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
except OSError:
gevent.sleep(0.1) # arbitrary number

[Sebastien Estienne]

Thanx Damien, that's the solution that i implemented.

[Sebastien Estienne]

Hi Vitaly,

Could you elaborate or give an example?

[vitaly]

On Monday, February 11, 2013 4:20:03 PM UTC-8, Sebastien Estienne wrote:

Hi Vitaly,

Could you elaborate or give an example?

Hi Sebastien, I was thinking of using a gevent-friendly/compatible threadpool just like the os.py module does (https://github.com/SiteSupport/gevent/blob/master/gevent/os.py) - e.g., tp_read, tp_write. I haven't tried this myself, but it seemed like using a gevent-compatible threadpool might solve the blocking issue, and would also avoid the latency that you might get from the other proposed solution that was based on polling.