On Thu, 23 Apr 2009 15:16:56 +0200, Piet van Oostrum <p...@cs.uu.nl> wrote:
marc wyburn <marc.wyb...@googlemail.com> (MW) wrote:
MW> Hi, I am writing an asynchronous ping app to check if 1000s of hosts
MW> are alive very quickly. Everything works extremely quickly unless the
MW> host name doesn't have a DNS record.
MW> when calling socket.gethostbyname if there is no record for the host
MW> the result seems to block all other threads. As an example I have 6
MW> threads running and if I pass the class below a Queue with about 30
MW> valid addresses with one invalid address in the middle the thread that
MW> the exception occurs in seems to block the others.
What you could do is have two Queues, one with host names, and one with
results from gethostbyname. And an additional thread which gets from the
first queue, calls gethostbyname and puts the results in the second queue.
The ping threads then should get from the second queue. The lookup
thread could even do caching of the results if you often have to repeat
the pings for thew same host.
You still end up limited to a single host lookup at a time with this
approach. Using a name lookup API which doesn't have this limitation
will probably produce significantly better results.
Jean-Paul
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