How to solve ORA-00031: session marked for kill?

Find out thread id that needed to be killed from OS level
[code] select vs.sid, vs.username, vs.osuser, vs.process fg_pid, vp.spid bg_pid from v$session vs, v$process vp where vs.paddr = vp.addr; [/code]
If you know the user detail you can filter the query.
[code] select vs.sid,vs.username,vs.osuser, vs.process,vp.spid from v$session vs, v$process vp where vs.paddr = vp.addr and vs.username='TEST_DAVID' and vs.osuser='TEST_DAVID'; Output: SID USERNAME OSUSER PROCESS SPID ---- --------------- ---------- --------- --------- 10 TEST_DAVID TEST_DAVID 2046:6845 8245 [/code]
Kill the session from OS level

Unix: Run in UNIX as the oracle/root user kill –9 spid

Example from the above output:

[code] kill -9 8245 [/code]