1. Threading Issues
A user presses a button on a web browser that stops a web page from loading any further:
The thread accepting the user stop button press
Wants the thread loading the page to be cancelled.

2. Signals, Messages
Signals are used in UNIX systems to notify a process that a particular event has occurred
A signal handler is used to process signals
Signal is generated by particular event
Signal is delivered to a process
Signal is handled
Every signal may be handled by one of two possible handlers:
1. A default signal handler
2. A user-defined signal handler

3. Signals generation, handling
Unix
Sending signals - kill(pid, SIGNAL) – send signal to other process (pid)
Handling signals - signal(SIGNAL, handling_function);
Windows WinAPI
Sending signals – InvalidateRect(x,y,x1,y1) – send signal to repaint the part of window.
Handling signals – case WM_PAINT {. . .}; or WM_... messages.

4. PThreads

5. Pthreads example

6. WinAPI Threads

7. Semantics of fork() and exec()
Does fork() duplicate only the calling thread or all threads in multithreaded environment ? (Unix)
There are two types of fork in different unix type systems:
fork() – that duplicates the whole context
fork() – that duplicates only a thread called the fork()
exec() – works as before replacing the whole space by the new program.
If exec is called immediately after forking, then duplicating all threads is unnecessary.

8. Threads
Linux Threads