Multithreading and other

Multithreading refers to POSIX.
Thread library. Pthread_create creates a thread, and pthread_join waits for the end of the thread. Mpcreatesemaphore create Signal
Volume, mpsignalsemaphore sends semaphores, mpwaitonsemaphore waits for a semaphores to continue, mpdeletesemaphore
Destroy semaphores.

You can create a release pool for the NSAID utoreleasepool management thread in a separate thread, and even a separate operation can be in a separate release pool.

Nstalog does not know why it is not useful in modal dialog.

Notification will be executed by the post thread, instead of registering the observe thread. To notify another thread to execute a function, use the mongomselecdomainmainthread or the cocoa port and conection mechanism.

The sheet function does not use modal, so its parent window will not be blocked, but the mouse and keyboard messages cannot be received on the parent window.