[IOS] Ch4 Multithreaded Programming

• A thread is a basic unit of CPU utilization

• Comprises
• a thread ID
• a program counter
• a register set
• a stack. 

• Shares with other threads belonging to the same process
• code section
• data section
• other operating-system resources(such as open files and signals)
  

• A traditional (or heavyweight) process has a single thread of control.

• If a process has multiple threads of control, it can perform more than one task at a time.

• multiprocess 的 overhead 比 multithreaded 大