Bugs item #583975, was opened at 2002-07-19 14:41 Message generated for change (Comment added) made by akuchling You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=583975&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Python Library Group: None Status: Open Resolution: None Priority: 5 Private: No Submitted By: Jason R. Mastaler (jasonrm) Assigned to: Nobody/Anonymous (nobody) Summary: gethostbyaddr lag Initial Comment: For more info, also see http://mail.python.org/pipermail/python-list/2002-July/113706.html Perl's gethostbyaddr doesn't seem to have this problem as shown below. Should I report this in the bug tracker? $ time perl -MSocket -lwe 'print +(gethostbyaddr inet_aton("datavortex.net"), AF_INET)[0]' datavortex.net real 0m0.063s user 0m0.050s sys 0m0.010s $ time python2 -c 'from socket import * ; print gethostbyaddr("datavortex.net")[0]' datavortex.net real 0m20.176s user 0m0.070s sys 0m0.020s ---------------------------------------------------------------------- >Comment By: A.M. Kuchling (akuchling) Date: 2006-12-22 08:11 Message: Logged In: YES user_id=11375 Originator: NO Was the cause of this bug ever diagnosed? Should this report remain open, or be closed? ---------------------------------------------------------------------- Comment By: Jason R. Mastaler (jasonrm) Date: 2003-07-24 23:03 Message: Logged In: YES user_id=85984 This problem has cropped up again for another TMDA user, so we still have this bug in Python. In short, just as with the previous report, this user sees a 20 second delay with socket.gethostbyaddr() on a hostname which all other tools (nslookup, host, mail progs, etc) look up instantaneously. In other words, Python is the only app on his system with this problem. I had him try Python 2.3c1 to no avail. As with the previous user, he is running Linux (Redhat): Linux sparge 2.4.20-18.7 #1 Thu May 29 06:51:53 EDT 2003 i686 unknown glibc-2.2.5-43 Any other information I should provide or any diagnostics I can have the user run? ---------------------------------------------------------------------- Comment By: Jason R. Mastaler (jasonrm) Date: 2002-11-02 23:40 Message: Logged In: YES user_id=85984 The problem was under Python 2.2. Though now the user reports that he can no longer reproduce the problem, despite not having done any Python upgrades or system configuration changes. We might just have to chuck this one up to FM (Funny Magic). ---------------------------------------------------------------------- Comment By: Neal Norwitz (nnorwitz) Date: 2002-11-02 16:14 Message: Logged In: YES user_id=33168 Jason, still with us? What version of python were you having the problem with? 2.1.x? 2.2.x? Do you have the problem with 2.2? Have you looked at patch #604210 (http://python.org/604210)? Can you test that? ---------------------------------------------------------------------- Comment By: Jason R. Mastaler (jasonrm) Date: 2002-09-06 20:20 Message: Logged In: YES user_id=85984 Still having the problem, but I'm unsure how to proceed. nslookup and host both return instantly when querying datavortex.net. Only Python seems to exhibit this problem, but it still could be a system misconfiguration. This is the only time I've ever seen/heard of this behavior. ---------------------------------------------------------------------- Comment By: Neal Norwitz (nnorwitz) Date: 2002-09-06 18:23 Message: Logged In: YES user_id=33168 Jason, are you still having this problem? Do you have anything to report? ---------------------------------------------------------------------- Comment By: Neal Norwitz (nnorwitz) Date: 2002-07-22 18:37 Message: Logged In: YES user_id=33168 Looking at the output, the problem is definitely in gethostbyaddr_r(). This is what python calls from Modules/socketmodule.c socket_gethostbyaddr(). Notice: the first attempt to send to the first DNS server "207.69.188.185" looks like it fails after 5 seconds. DNS #2 is attempted "207.69.188.186", this send also takes 5 seconds, back to #1 ... The poll is being done in gethostbyaddr_r() (ie, libc). If you want to break in a debugger, gethost...() should be around line 2216 in python 2.2. You can also put prints in. As for why perl doesn't have the same problem, it could be that perl doesn't use the same library call (gethostbyaddr_r), or attempts to read from /etc/hosts before contacting the DNS server. I'm just guessing. In order to debug this further, you will probably need the python sources. What happens if you do host datavortex.net (you could also try nslookup)? Does that return immediately or wait? ---------------------------------------------------------------------- Comment By: Data Vortex (datavortex) Date: 2002-07-22 15:15 Message: Logged In: YES user_id=141979 Running strace python2 -c 'from socket import * ; print getfqdn()', I can see a pause of several seconds during the output of: socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3 connect(3, {sin_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("207.69.188.185")}}, 28) = 0 send(3, ")\351\1\0\0\1\0\0\0\0\0\0\ndatavortex\3net\0\0\34\0\1", 32, 0) = 32 gettimeofday({1027364850, 154497}, NULL) = 0 poll([{fd=3, events=POLLIN, revents=POLLIN}], 1, 5000) = 1 recvfrom(3, ")\351\201\200\0\1\0\0\0\1\0\0\ndatavortex\3net\0\0\34\0"..., 1024, 0, {sin_family=AF_INET, sin_p ort=htons(53), sin_addr=inet_addr("207.69.188.185")}}, [16]) = 95 close(3) = 0 socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3 connect(3, {sin_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("207.69.188.185")}}, 28) = 0 send(3, ")\352\1\0\0\1\0\0\0\0\0\0\ndatavortex\3net\3net\0"..., 36, 0) = 36 gettimeofday({1027364850, 169212}, NULL) = 0 poll([{fd=3, events=POLLIN}], 1, 5000) = 0 socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 4 connect(4, {sin_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("207.69.188.186")}}, 28) = 0 send(4, ")\352\1\0\0\1\0\0\0\0\0\0\ndatavortex\3net\3net\0"..., 36, 0) = 36 gettimeofday({1027364855, 172955}, NULL) = 0 poll([{fd=4, events=POLLIN}], 1, 5000) = 0 send(3, ")\352\1\0\0\1\0\0\0\0\0\0\ndatavortex\3net\3net\0"..., 36, 0) = 36 gettimeofday({1027364860, 182024}, NULL) = 0 poll([{fd=3, events=POLLIN, revents=POLLIN}], 1, 5000) = 1 recvfrom(3, "<\310\201\202\0\1\0\0\0\0\0\0\ndatavortex\3net\3net\0"..., 1024, 0, {sin_family=AF_INET, sin_por t=htons(53), sin_addr=inet_addr("207.69.188.185")}}, [16]) = 36 poll([{fd=3, events=POLLIN}], 1, 5000) = 0 send(4, ")\352\1\0\0\1\0\0\0\0\0\0\ndatavortex\3net\3net\0"..., 36, 0) = 36 gettimeofday({1027364865, 191273}, NULL) = 0 The full output of this command is availible here: http://datavortex.net/out.txt ---------------------------------------------------------------------- Comment By: Neal Norwitz (nnorwitz) Date: 2002-07-20 17:09 Message: Logged In: YES user_id=33168 That's a good idea Jack. On Linux, you can use strace. On Solaris, I believe the program is called truss. $ strace python ... ---------------------------------------------------------------------- Comment By: Jack Jansen (jackjansen) Date: 2002-07-20 17:03 Message: Logged In: YES user_id=45365 Here's a few ideas on debugging this: - Easiest would be if you have a system call tracer. Attach it to the process and see during what system call the 20 second wait occurs. Then look at it's parameters and see whether there's anything fishy. Or whether you can recreate the problem in C. - If you don't have a tracer first split the program in two steps: the implicit gethostbyname() step and the gethostbyaddr() step. see which one is the problem. Run this step under the debugger and see where the delay is. Again, try to recreate the problem. ---------------------------------------------------------------------- Comment By: Neal Norwitz (nnorwitz) Date: 2002-07-20 12:02 Message: Logged In: YES user_id=33168 Does this happen consistently (every run) or only the first time? Works fine for me (Linux). What OS are you on? ---------------------------------------------------------------------- Comment By: Jason R. Mastaler (jasonrm) Date: 2002-07-19 17:46 Message: Logged In: YES user_id=85984 I'm not ruling it out that it could be a local configuration problem, it's just that Python is the only application experiencing this delay. We've gone through the network configuration and everything seems sound, so I'm not sure what more to do. /etc/resolv.conf is fine -- all entries are operational nameservers. ---------------------------------------------------------------------- Comment By: Jack Jansen (jackjansen) Date: 2002-07-19 17:42 Message: Logged In: YES user_id=45365 This smells like a local configuration bug on your system, on my system it works fine (0.220u 0.110s 0:01.85 17.8% 0+0k 84+10io 0pf+0w). Look in your /etc/resolv.conf (or similar file for your platform) to see that there aren't any non-existing hosts listed there. Although, of course, that doesn't explain why perl has no delay... ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=583975&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
