Hi Carlos,
I looked in the source code for pylibpcap, and it does not release the GIL, hence my problem.
I found a solution though, the pcap object has a fileno member so I could use select to wait for a packet, then call loop without blocking. Problem solved! :)
And since it is only a thin wrapper over the pcap library it (seems to be) ok to open multiple instances of pcap, at least so long the different istances does select a separate interface. At least it works for me now!
And thank you for the link to http://libdnet.sourceforge.net it solved my next problem to send raw packets from python.
/Örjan Gustavsson
Carlos Ribeiro wrote:
On Mon, 24 Jan 2005 15:18:39 +0100, Örjan Gustavsson <[EMAIL PROTECTED]> wrote:
Hi All!
Sorry if this is not the correct forum for this kind of question (I did not find any pylibpcap related lists).
I am trying to use pylibpcap to capture network traffic from several ethernet devices at the same time, each nic having a separate thread assigned to it.
My problem is that when one thread is blocking inside pcap.loop() for instance, it seems to have acquired the GIL, so that no other threads can run.
Does anyone know a way to do this with threads, or is the only way to have separate processes for each NIC?
From the top of my head, and without any test. I did use libpcap forsome stuff recently. loop() is the primitive that keeps reading and calls the callback, right? I believe that it should release the GIL in the C wrapper code, right before calling the libpcap loop implementation, and re-acquire it before calling the callback. There is a standard way to do it, that is used before blocking calls are issued (file writing, for example). If it fails to release the GIL it will block.
I'm also not sure if the libpcap itself is supposed to be used this way - with multiple instances - but I assume that it should work (I never tried to open several instances of tcpdump at the same time).
Also, check these links also, as they may be helpful to you:
http://libdnet.sourceforge.net/ http://oss.coresecurity.com/projects/pcapy.html
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