Re: Possible DNS problem (truss)

Posted in 2011

Fernando Nunes — Mon, 13 Jun 2011 16:09:20 — source: IIUG Forums & Mailing Lists

There are a few things I don't understand in this output. First, you're assuming that certain "sockets()" are for talking to the DNS. I don't see any evidences about that. Unfortunately I don't know how to convince "truss" on AIX to give us the hostnames and ports... Then, there is a message: truss: 0915-023 Cannot control process #602984 which I don't understand. What is PID 602984 and 680782? What options did you use on truss? If you want to "truss" a dbaccess why don't you just call "truss -o output.txt <your truss options> dbaccess your_database ? Then, if you're having slow DNS, you'll have slow connects (maybe your 30s are just the time the engine takes to reverse dns you client IP) Regards. On Mon, Jun 13, 2011 at 11:37 AM, Dirk Cornel.... <moolma_dc@mtn.co.za>wrote: > AIX 5 > IDS 10 > > Ok, this is what I did: > > 1. I opened 2 telnet sessions > > 2. On the 1st I connected to the database (using a tcp connection and > dbaccess) - "dbaccess <databasename>" > > 3. On the 2nd, I got the PID for the 1st session, and did a truss on that > PID, > and below is what I found. > > truss: 0915-023 Cannot control process #602984. > 680782: _poll(0x0000000000000000, 0, 0) (sleeping...) > 680782: _poll(0x0000000000000000, 0, 0) = 0 > 680782: close(7) = 0 > 680782: socket(2, 2, 0) = 7 > 680782: sendto(7, 0x0FFFFFFFFFFF9190, 24, 0, 0x09001000A0015AB8, 16) = 24 > 680782: _poll(0x0FFFFFFFFFFF8330, 1, 5000) (sleeping...) > 680782: _poll(0x0FFFFFFFFFFF8330, 1, 5000) = 0 > 680782: close(7) = 0 > 680782: socket(2, 2, 0) = 7 > 680782: sendto(7, 0x0FFFFFFFFFFF9190, 24, 0, 0x09001000A0015AB8, 16) = 24 > 680782: _poll(0x0FFFFFFFFFFF8330, 1, 10000) (sleeping...) > 680782: _poll(0x0FFFFFFFFFFF8330, 1, 10000) = 0 > 680782: close(7) = 0 > 680782: socket(2, 2, 0) = 7 > 680782: sendto(7, 0x0FFFFFFFFFFF9190, 24, 0, 0x09001000A0015AB8, 16) = 24 > 680782: _poll(0x0FFFFFFFFFFF8330, 1, 20000) (sleeping...) > 680782: _poll(0x0FFFFFFFFFFF8330, 1, 20000) = 0 > 680782: close(7) = 0 > 680782: close(6) = 0 > > The truss runs up to here, and then hangs for 30 seconds. And then > suddenly, > when the 1st session connects, it continues as follows: > > 680782: open("/etc/hosts", O_RDONLY) = 6 > 680782: kioctl(6, 22528, 0x0000000000000000, 0x0000000000000000) = -1 > 680782: kfcntl(6, F_SETFD, 0x0000000000000001) = 0 > 680782: kioctl(6, 22528, 0x0000000000000000, 0x0000000000000000) = -1 > 680782: kread(6, " # I n t e r n e t A".., 4096) = 640 > 680782: kread(6, " # I n t e r n e t A".., 4096) = 0 > 680782: close(6) = 0 > 680782: socket(24, 1, 0) = 6 > 680782: kfcntl(6, F_GETFL, 0x0000000000000000) = 2 > 680782: kioctl(6, -2147195266, 0x0FFFFFFFFFFFC300, 0x0000000000000000) = 0 > 680782: kioctl(6, -2147195267, 0x0FFFFFFFFFFFC300, 0x0000000000000000) = 0 > 680782: kfcntl(6, F_SETFL, 0x0000000000008002) = 0 > 680782: getsockopt(6, 65535, 4104, 0x0FFFFFFFFFFFC434, 0x0FFFFFFFFFFFC430) > = 0 > 680782: connext(6, 0x00000001100D0C90, 28) = 0 > 680782: kioctl(6, -2147195266, 0x0FFFFFFFFFFFC300, 0x0000000000000000) = 0 > 680782: kioctl(6, -2147195267, 0x0FFFFFFFFFFFC300, 0x0000000000000000) = 0 > 680782: kfcntl(6, F_SETFL, 0x0000000000000012) = 0 > 680782: setsockopt(6, 65535, 4, 0x0FFFFFFFFFFFC410, 4) = 0 > 680782: setsockopt(6, 65535, 8, 0x0FFFFFFFFFFFC410, 4) = 0 > 680782: setsockopt(6, 65535, 128, 0x0FFFFFFFFFFFC418, 8) = 0 > 680782: setsockopt(6, 6, 1, 0x0FFFFFFFFFFFC410, 4) = 0 > 680782: send(6, 0x00000001100E9430, 391, 0) = 391 > 680782: recv(6, 0x00000001100ED450, 16384, 0) = 271 > 680782: send(6, 0x00000001100E9430, 14, 0) = 14 > 680782: recv(6, 0x00000001100ED450, 16384, 0) = 14 > 680782: send(6, 0x00000001100E9430, 442, 0) = 442 > 680782: recv(6, 0x00000001100ED450, 16384, 0) = 2 > 680782: send(6, 0x00000001100E9430, 28, 0) = 28 > 680782: recv(6, 0x00000001100ED450, 16384, 0) = 46 > 680782: kwrite(1, "1B [ ? 1 h1B [ H1B [ 2 J".., 38) = 38 > 680782: send(6, 0x00000001100E9430, 8, 0) = 8 > 680782: recv(6, 0x00000001100ED450, 16384, 0) = 28 > 680782: access("eppix.dbs", 0) = -1 > 680782: access("./eppix.dbs", 0) = -1 > 680782: access("/usr/informix/msg/en_us/0333/sql.iem", 04) = 0 > 680782: close(3) = 0 > 680782: open("/usr/informix/msg/en_us/0333/sql.iem", O_RDONLY|O_LARGEFILE) > = 3 > 680782: kread(3, " þ h068C", 4) = 4 > 680782: klseek(3, 6700, 0, 0x0FFFFFFFFFFFD580) = 0 > 680782: kread(3, " ý F\\\\0 H\\\\0\\\\088 × ý G\\\\0 #".., 64) = 64 > 680782: klseek(3, 10084, 0, 0x0FFFFFFFFFFFD580) = 0 > 680782: kread(3, " þ õ\\\\0 <\\\\0\\\\0 ? · þ ö\\\\0 2".., 64) = 64 > 680782: klseek(3, 11772, 0, 0x0FFFFFFFFFFFD580) = 0 > 680782: kread(3, "03 \\\\011\\\\0\\\\0 ¸ q03 ¡\\\\00F".., 64) = 64 > 680782: klseek(3, 10956, 0, 0x0FFFFFFFFFFFD580) = 0 > 680782: kread(3, "03 6\\\\00F\\\\0\\\\0 ° h03 9\\\\00F".., 64) = 64 > 680782: klseek(3, 10548, 0, 0x0FFFFFFFFFFFD580) = 0 > 680782: kread(3, " ÿ /\\\\01E\\\\0\\\\0 6 K ÿ 0\\\\0 2".., 64) = 64 > 680782: klseek(3, 10780, 0, 0x0FFFFFFFFFFFD580) = 0 > 680782: kread(3, "031D\\\\014\\\\0\\\\0 ® ½031E\\\\012".., 64) = 64 > 680782: klseek(3, 44789, 0, 0x0FFFFFFFFFFFD4D0) = 0 > 680782: kread(3, " D a t a b a s e s e l".., 19) = 19 > 680782: kwrite(1, "1B [ 2 4 ; 2 H D a t a b".., 25) = 25 > 680782: sigprocmask(0, 0x0000000000000000, 0x0000000110059340) = 0 > 680782: kwrite(1, "1B [ H1B [ 2 J D B A C C".., 252) = 252 > 680782: kread(0, "\\\\0", 1) (sleeping...) > > The problem is, I spoke to the Unix Admin, and he says that we resolve in > /etc/hosts (locally) first, and then only on DNS, whereas I thought it is > working the other way around. > > My netsvc.conf file contains: > hosts=local, bind4, bind6 > > This confirms what the Unix Admin says, but if I read the truss output, > then > it is not happening this way. What I read from the truss output (if I > understand it correctly), is that it tries to resolve the hostname > (PS. We are using a hostname in the sqlhosts file, and not an IP address). > So, after 30 seconds of trying to resolve the hostname, it opens the > /etc/hosts file, gets the IP, and connect. I am correct when I say this ? > > Dirk > > ________________________________ > NOTE: This e-mail message is subject to the MTN Group disclaimer see > http://www.mtn.co.za/SUPPORT/LEGAL/Pages/EmailDisclaimer.aspx > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > -- Fernando Nunes Portugal http://informix-technology.blogspot.com My email works... but I don't check it frequently... --001636c5bd697b647504a59a224c