How to handle exception?try ... finally ... don't working.

[MK2]

Some problem when an exception raise, example:

conn = somepool.get()
try:
    # do some operations
    yield conn.execute() # when here `conn.execute()` inside raise an
exception.
finally:
    somepool.put(conn) # this logic code wouldn't execute forever.

How to let `try ... finally ... ` work as normal?