How-to trace oracle sessions?

There are lots of methods to trace oracle sessions.

1. alter session set events ‘10046 trace name context forever,level 12′;

alter session set tracefile_identifier=’10046′;
alter session set timed_statistics = true;
alter session set statistics_level=all;
alter session set max_dump_file_size = unlimited;

Start trace:

alter session set events ‘10046 trace name context forever,level 12′;

Stop trace:

alter session set events ‘10046 trace [...]