Subject: Query against V$SESSION hangs on 10g RAC systems 2007-11-01 - By Dean
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We recently had a locking/blocking problem on two different 10.2.0.3 RAC
systems. I ran a query similar to below to get more information:
select sid, serial#, program, module, action, username, osuser,
sql_hash_value, machine, event, blocking_session
from v$session
where status='ACTIVE';
About 1 out of 5 times this query hangs. When it hangs, it waits for
exactly 60 seconds on "DIAG idle wait" and then returns the result set. If
I remove the blocking_session column, this query runs fine and never hangs.
Has anyone run into this or have any ideas why this would happen?
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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>We recently had a locking/blocking problem on two different
10.2.0.3 RAC systems. I ran a query similar to below to get more
information:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New">
<span
style='font-size:10.0pt;font-family:"Courier New"'>select sid, serial#,
program, module, action, username, osuser,<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New">
<span
style='font-size:10.0pt;font-family:"Courier New"'>sql_hash_value, machine,
event,
blocking_session <o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New">
<span
style='font-size:10.0pt;font-family:"Courier New"'>from v$session <o:p></o:p><
/span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New">
<span
style='font-size:10.0pt;font-family:"Courier New"'>where status='ACTIVE';<o:p><
/o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face="Courier New">
<span
style='font-size:10.0pt;font-family:"Courier New"'><o:p> </o:p></span><
/font></p>
<p class=MsoNormal style='text-autospace:none'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>About 1 out of 5 times this query
hangs. When it hangs, it waits for exactly 60 seconds on “DIAG idle
wait” and then returns the result set. If I remove the
blocking_session column, this query runs fine and never hangs. Has anyone
run into this or have any ideas why this would happen?<o:p></o:p></span></font>
</p>
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