Sorry for the late reply, peter_foelsche@agilent.com wrote:
I think this (synchronization) is overkill. Most people want memory mapped io to write/read from files. Synchronization is not necessary. Of course creating new elements in a readonly file would fail.
I've added read-only managed classes to my to-do list. The idea would be to create both shared_memory_object/file_mapping/mapped_regions with read-only attributes and avoid internal locking. I'm afraid this will require some important refactoring because I'll need to avoid internal locking calls in the segment manager placed in shared memory, without storing a read-only bit in the segment manager (because it can be later opened for read-write). I can't say when it would be ready, though.
in a sparse file (the default on UNIXs) diskspace is only allocated when needed.
I'll also add this to my to-do list. Thanks for your suggestions. If you have more, please let me know. Regards, Ion