Hi I recently read an article how KDevelop handles threading and that got me thinking. As far as I understand Pier currently uses a global lock for all write operations (where #isView returns false). All good an fine so far. But shouldn't this be a a read-write lock? Imagine the following scenario: - a view command is executed, is starts to read some objects, iterates over some objects - the current process is unscheduled - a new process is with a write command is scheduled, it executes to completion - the original view command is scheduled a again but it has inconsistent information, eg the parent of an already read structure has changed A read-write lock should not affect performance because it allows multiple concurrent readers. Cheers Philippe