SELECT FOR UPDATE

Hi all,

I'm trying SELECT FOR UPDATE
but I have a problem with locks.

example:
I have two users accessing to the same records, say...

user1:
DELECT * FROM table WHERE field=value FOR UPDATE
---------------------------------------------------------------------------

user2:
DELECT * FROM table WHERE field=value FOR UPDATE
at this point user2 can't do nothing except waiting for user1 unlock recors.

My question is:

- Is it possible to know  in advance if the records of a given query are
locked, to prevent to be locked for ever?

Thank for any help,

Jose Soares