Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
On Mon, Sep 2, 2013 at 3:28 PM, anntzer@gmail.com wrote: On Sunday, September 1, 2013 2:03:56 PM UTC-7, Chris Angelico wrote: I tried using netifaces (https://pypi.python.org/pypi/netifaces) which seems to rely on getifaddrs (according to the doc, I didn't check the source). Again, it returns nearly instantaneously the correct IP address. Perfect! ChrisA Not really for my use case -- it isn't that *I* want to know my public IP address, but rather that IPython wants to know it. Of course I could patch IPython's source to use netifaces but that sounds like an overkill. As it happens I found a better way: just add the proper entry to /etc/hosts. Ah, I see what you mean. If it were possible with core Python, I would recommend raising a bug with IPython, as the current method is susceptible to external issues. But to just get your problem solved, yes, a host file entry sounds like it's the best way to go. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
In article 00843d58-db21-4cf0-9430-85362a1dd...@googlegroups.com, anntzer@gmail.com wrote: As it happens I found a better way: just add the proper entry to /etc/hosts. You have not found a better way. You still have a network (or more specifically, DNS) configuration that's broken. What you have found is a pragmatic way to solve your immediate problem and get some work done. That is certainly useful (and I've done it plenty of times), but you need to understand that what you've done is hidden the problem, not solved it. -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
On Monday, September 2, 2013 5:45:26 AM UTC-7, Roy Smith wrote: In article 00843d58-db21-4cf0-9430-85362a1dd...@googlegroups.com, anntzer@gmail.com wrote: As it happens I found a better way: just add the proper entry to /etc/hosts. You have not found a better way. You still have a network (or more specifically, DNS) configuration that's broken. What you have found is a pragmatic way to solve your immediate problem and get some work done. That is certainly useful (and I've done it plenty of times), but you need to understand that what you've done is hidden the problem, not solved it. To be honest, knowing nothing about DNS configuration, I don't even know if adding the entry to /etc/hosts is the proper fix or if the issue should be fixed somewhere else (or perhaps didn't know, as you seem to imply that that is not the correct way). -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
On Tue, Sep 3, 2013 at 3:52 AM, anntzer@gmail.com wrote: To be honest, knowing nothing about DNS configuration, I don't even know if adding the entry to /etc/hosts is the proper fix or if the issue should be fixed somewhere else (or perhaps didn't know, as you seem to imply that that is not the correct way). Since you can't change the code, it's almost certainly the best solution available to you. It's more-or-less equivalent to speeding up your DNS lookups massively. The main downside is that if something changes, you need to change it in DNS and in your hosts file; as Roy says, it's a pragmatic solution rather than a perfect one. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
In article 48c8f8ca-d8c1-4a60-ba7f-8e8b00993...@googlegroups.com, anntzer@gmail.com wrote: It is the call to gethostbyname_ex that is very slow. The call to gethostname is quick (and returns the same string as /usr/bin/hostname). First, please stop posting with Google Groups. It makes a total mess of the quoted text. Next, what happens when you use the command-line tools (nslookup or dig) to translate your hostname to an IP address, and what happens if you then try to reverse translate that IP address back to a name? This issue is independent of IPython: $ time python -c 'import socket; print(socket.gethostbyname_ex(socket.gethostname())[2])' ['192.168.0.102'] python -c 0.07s user 0.02s system 0% cpu 28.190 total The real point is not that it's independent of IPython, it has nothing to do with Python at all. What you've got here is a network configuration issue. You would do better to recreate this problem with the native OS command line tools and then ask about it on a forum dedicated to your operating system. -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
On Sun, Sep 1, 2013 at 10:03 AM, anntzer@gmail.com wrote: At startup, IPython (qtconsole) calls socket.gethostbyname_ex(socket.gethostname())[2] to find a list of IP addresses that point to the machine. On a Linux server that I manage this call is extremely slow (20s)... which I have trouble understanding as ip addr show seems to give the same information nearly instantaneously. Is there anything I can do to make this faster? Can this be a network configuration issue (I am behind a router)? Yes, it most definitely CAN be a network config issue. The C function you want to be calling is getifaddrs(), and I don't think there's a way to call that from core Python. But a Google search for 'python getifaddrs' shows up a few third-party modules that might be of use to you; that'd be a lot quicker and more reliable than trying to look up your own hostname and depending on the results. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
On Saturday, August 31, 2013 10:06:43 PM UTC-7, Michael Torrie wrote: On 08/31/2013 10:51 PM, anntzer@gmail.com wrote: It is the call to gethostbyname_ex that is very slow. The call to gethostname is quick (and returns the same string as /usr/bin/hostname). What gethostbyname_ex and /usr/bin/hostname do are very different things. gethostbyname_ex does a DNS lookup against a server. /usr/bin/hostname just checks a local computer setting. I don't see why you are comparing the two. /usr/bin/hostname is not going to help you find a list of IP addresses that point to a machine. I was just replying to the previous comment name = socket.gethostname() see how long that takes and what it returns. Then, assuming it returns a string containing your hostname (massive handwave about what that actually means), saying that gethostname resolves my own hostname instantaneously. -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
On Sunday, September 1, 2013 4:37:34 AM UTC-7, Chris Angelico wrote: Yes, it most definitely CAN be a network config issue. The C function you want to be calling is getifaddrs(), and I don't think there's a way to call that from core Python. But a Google search for 'python getifaddrs' shows up a few third-party modules that might be of use to you; that'd be a lot quicker and more reliable than trying to look up your own hostname and depending on the results. ChrisA I tried using netifaces (https://pypi.python.org/pypi/netifaces) which seems to rely on getifaddrs (according to the doc, I didn't check the source). Again, it returns nearly instantaneously the correct IP address. -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
On Mon, Sep 2, 2013 at 6:37 AM, anntzer@gmail.com wrote: On Sunday, September 1, 2013 4:37:34 AM UTC-7, Chris Angelico wrote: Yes, it most definitely CAN be a network config issue. The C function you want to be calling is getifaddrs(), and I don't think there's a way to call that from core Python. But a Google search for 'python getifaddrs' shows up a few third-party modules that might be of use to you; that'd be a lot quicker and more reliable than trying to look up your own hostname and depending on the results. ChrisA I tried using netifaces (https://pypi.python.org/pypi/netifaces) which seems to rely on getifaddrs (according to the doc, I didn't check the source). Again, it returns nearly instantaneously the correct IP address. Perfect! ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
On Sunday, September 1, 2013 2:03:56 PM UTC-7, Chris Angelico wrote: I tried using netifaces (https://pypi.python.org/pypi/netifaces) which seems to rely on getifaddrs (according to the doc, I didn't check the source). Again, it returns nearly instantaneously the correct IP address. Perfect! ChrisA Not really for my use case -- it isn't that *I* want to know my public IP address, but rather that IPython wants to know it. Of course I could patch IPython's source to use netifaces but that sounds like an overkill. As it happens I found a better way: just add the proper entry to /etc/hosts. Still, thanks for the suggestions. Antony -- http://mail.python.org/mailman/listinfo/python-list
gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
Hi, At startup, IPython (qtconsole) calls socket.gethostbyname_ex(socket.gethostname())[2] to find a list of IP addresses that point to the machine. On a Linux server that I manage this call is extremely slow (20s)... which I have trouble understanding as ip addr show seems to give the same information nearly instantaneously. Is there anything I can do to make this faster? Can this be a network configuration issue (I am behind a router)? This issue is independent of IPython: $ time python -c 'import socket; print(socket.gethostbyname_ex(socket.gethostname())[2])' ['192.168.0.102'] python -c 0.07s user 0.02s system 0% cpu 28.190 total Thanks. Antony -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
In article b9f77b6f-3a65-407a-aff5-5677be2ba...@googlegroups.com, anntzer@gmail.com wrote: Hi, At startup, IPython (qtconsole) calls socket.gethostbyname_ex(socket.gethostname())[2] to find a list of IP addresses that point to the machine. On a Linux server that I manage this call is extremely slow (20s)... which I have trouble understanding as ip addr show seems to give the same information nearly instantaneously. Is there anything I can do to make this faster? Can this be a network configuration issue (I am behind a router)? It's almost certainly some sort of configuration issue which is causing some DNS query to timeout. The first step, is to figure out which part is taking so long. Open up a python shell and run: name = socket.gethostname() see how long that takes and what it returns. Then, assuming it returns a string containing your hostname (massive handwave about what that actually means), try socket.gethostbyname_ex(name) and see how long that takes and what it returns. At least at that point you'll have cut the problem in half. If I had to guess, you've got a missing PTR record, because that's what most people screw up. -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
It is the call to gethostbyname_ex that is very slow. The call to gethostname is quick (and returns the same string as /usr/bin/hostname). On Saturday, August 31, 2013 6:01:00 PM UTC-7, Roy Smith wrote: In article b9f77b6f-3a65-407a-aff5-5677be2ba...@googlegroups.com, anntzer@gmail.com wrote: Hi, At startup, IPython (qtconsole) calls socket.gethostbyname_ex(socket.gethostname())[2] to find a list of IP addresses that point to the machine. On a Linux server that I manage this call is extremely slow (20s)... which I have trouble understanding as ip addr show seems to give the same information nearly instantaneously. Is there anything I can do to make this faster? Can this be a network configuration issue (I am behind a router)? It's almost certainly some sort of configuration issue which is causing some DNS query to timeout. The first step, is to figure out which part is taking so long. Open up a python shell and run: name = socket.gethostname() see how long that takes and what it returns. Then, assuming it returns a string containing your hostname (massive handwave about what that actually means), try socket.gethostbyname_ex(name) and see how long that takes and what it returns. At least at that point you'll have cut the problem in half. If I had to guess, you've got a missing PTR record, because that's what most people screw up. -- http://mail.python.org/mailman/listinfo/python-list
Re: gethostbyname_ex(hostname) extremely slow (crossposted from stackoverflow)
On 08/31/2013 10:51 PM, anntzer@gmail.com wrote: It is the call to gethostbyname_ex that is very slow. The call to gethostname is quick (and returns the same string as /usr/bin/hostname). What gethostbyname_ex and /usr/bin/hostname do are very different things. gethostbyname_ex does a DNS lookup against a server. /usr/bin/hostname just checks a local computer setting. I don't see why you are comparing the two. /usr/bin/hostname is not going to help you find a list of IP addresses that point to a machine. -- http://mail.python.org/mailman/listinfo/python-list
