library cache pin & library cache lock

Once there was an error on one of our production database. I saw some process awaiting for "library cache lock". One process was in "library cache pin' state. This situation was expected during table partition movement operation.

As I understood it was a consequences of invalid package which became invalid due to "alter table XXX move partition". Session 388 was getting library cache pin when he or some system process had been tried to recompile invalid object during partition movement. The others were waiting for 388 process to get a lock. After partition had been moved successfully package was recompiled and the queue disappeared.