tag:blogger.com,1999:blog-5309604992043123290.post829943955889023898..comments2024-03-24T11:22:17.354+01:00Comments on berxblog: who cares if a listener is dyingMartin Bergerhttp://www.blogger.com/profile/16504572924713610305noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-5309604992043123290.post-39918370225349649522012-05-08T11:01:01.302+02:002012-05-08T11:01:01.302+02:00Hi Martin,
I think sniffing network could be a goo...Hi Martin,<br />I think sniffing network could be a good start to see if survived host is trying to contact evicted host. tcpdump plus netstat should be good starting point.<br /><br />regards,<br />MarcinMarcin Przepiorowskihttps://www.blogger.com/profile/15133397892511680504noreply@blogger.comtag:blogger.com,1999:blog-5309604992043123290.post-12570893966103171172012-05-07T08:45:00.263+02:002012-05-07T08:45:00.263+02:00Yury,
yes, it sounds right.
I just don't know ...Yury,<br />yes, it sounds right.<br />I just don't know if PMONs 3 sec. interval can be changed;<br />I also don't know if LISTENER polls it's TCP connection from PMON (async) or catches it's failure and reacts immediately. <br />Both is something I would need a debugger and knowledge in these tasks. I'm just not trained in debug into that level.Martin Bergerhttps://www.blogger.com/profile/16504572924713610305noreply@blogger.comtag:blogger.com,1999:blog-5309604992043123290.post-33072081947535911752012-05-07T02:15:26.425+02:002012-05-07T02:15:26.425+02:00I think we are getting there. We now have a good r...I think we are getting there. We now have a good repeatable case. We see that after some time SCAN got updated up to the right status. Now it is time to confirm that our understanding of events is right:<br />- If Listener goes down. PMON verifies listeners on 3 secs bases (is it default time frame? is there any way we can change it?). If no listener found it notifies SCAN listeners. SCAN listeners clean up the info<br />- If local PMON and Listener goes down. "This is at least an indication SCAN LISTENER wipes out all the infos from a PMON when it loses it's TCP connection.". It looks like SCAN Listeners checks if connection to PMON is alive on regular basis (what is the time frame? can we change it?) and if it isn't alive it cleans up all the information provided before by the PMON <br /><br />Does it sound right?<br /><br />YuryYuryhttps://www.blogger.com/profile/14080741737423964389noreply@blogger.comtag:blogger.com,1999:blog-5309604992043123290.post-57104924549648694512012-05-06T20:39:21.212+02:002012-05-06T20:39:21.212+02:00Yury,
I tried the small testcase:
lsnrctl servic...Yury, <br />I tried the small testcase:<br /><i><br />lsnrctl service LISTENER_SCAN2 > /tmp/lsnr3.txt; kill -9 `pgrep -f ora_pmon_TTT041` ; lsnrctl service LISTENER_SCAN2 > /tmp/lsnr4.txt</i><br />in <i>/tmp/lsnr3.txt</i> I found (as expected)<br /><i>Service "TTT04_SITE1" has 2 instance(s).<br /><b> Instance "TTT041", status READY, has 1 handler(s) for this service...<br /> Handler(s):<br /> "DEDICATED" established:0 refused:0 state:ready<br /> REMOTE SERVER<br /> (ADDRESS=(PROTOCOL=TCP)(HOST=<host1>-vip)(PORT=1521))</b><br /> Instance "TTT042", status READY, has 1 handler(s) for this service...<br /> Handler(s):<br /> "DEDICATED" established:0 refused:0 state:ready<br /> REMOTE SERVER<br /> (ADDRESS=(PROTOCOL=TCP)(HOST=<host2>-vip)(PORT=1521))</i><br /><br />and in <i>/tmp/lsnr4.txt</i>:<br /><i>Service "TTT04_SITE1" has 1 instance(s).<br /> Instance "TTT042", status READY, has 1 handler(s) for this service...<br /> Handler(s):<br /> "DEDICATED" established:0 refused:0 state:ready<br /> REMOTE SERVER<br /> (ADDRESS=(PROTOCOL=TCP)(HOST=<host2>-vip)(PORT=1521))</i><br /><br />You can see, <b>directly</b> after I killed PMON, LISTENER_SCAN2 did not mention it's instance <b>TTT041</b> anymore. This is at least an indication PMON wipes out all the infos from a PMON when it loses it's TCP connection. <br /><br />So here I did not have any gap at all.Martin Bergerhttps://www.blogger.com/profile/16504572924713610305noreply@blogger.comtag:blogger.com,1999:blog-5309604992043123290.post-32996707135553423702012-05-06T12:14:29.229+02:002012-05-06T12:14:29.229+02:00What happens is a node goes down? There is no PMON...What happens is a node goes down? There is no PMON process to inform SCAN that a local listener disappeared?<br /><br />YuryYuryhttps://www.blogger.com/profile/14080741737423964389noreply@blogger.com