Although the PGA_AGGREGATE_LIMIT is set and Oracle decided to kill the process/session that was using so much, it sometimes still exceeds and grows and eventually exhausting all the memory.
SQL> show parameter pga_aggregate_limit NAME TYPE VALUE ------------------------------- ----------- ------------------------------ pga_aggregate_limit big integer 14G SQL> select round(pga_used_mem/1024/1024) PGA_USED_MEM from v$process p join v$session s on p.addr = s.paddr where s.sid = 259; PGA_USED_MEM ------------ 14928 SQL> / PGA_USED_MEM ------------ 15015
From the alert log:
KILL SESSION for sid=(259, 29568): Reason = alter system kill session Mode = KILL HARD SAFE -/-/- Requestor = USER (orapid = 25, ospid = 4952, inst = 1) Owner = Process: USER (orapid = 148, ospid = 5628) Result = ORA-31
The culprit here is the ORA-31 error. This is the ‘marked for kill’ message. So the process is not killed, but only marked for kill:
select sid, serial#, status from v$session where sid = 259; sid serial# status --- ------- ------ 259 29568 KILLED
This means it will wait until the process/session is done with it’s uninterruptible work, before it’s really killed. If this takes long, it will keep eating up memory until your host has no memory left.
ORA-00031: session marked for kill
00031. 00000 - "session marked for kill"
*Cause: The session specified in an ALTER SYSTEM KILL SESSION command
cannot be killed immediately (because it is rolling back or blocked
on a network operation), but it has been marked for kill. This
means it will be killed as soon as possible after its current
uninterruptable operation is done
Action: No action is required for the session to be killed, but further
executions of the ALTER SYSTEM KILL SESSION command on this session
may cause the session to be killed sooner.
For Windows there is an other ‘official’ way to get rid of this, and that;s using the `orakill` command:
select p.spid from v$process p join v$session s on p.addr = s.paddr where s.sid = 259 and s.serial# = 29568; spid ---- 5628 > orakill <SID> 5628
It will take a few minutes, but then the process/session is gone and memory is freed!