提供以下功能：
- automatic notification of new threads
- ‘thread threadno’, a command to switch among threads
- ‘info threads’, a command to inquire about existing threads
- ‘thread apply [threadno] [all] args’, a command to apply a command to a list of threads
- thread-specific breakpoints
- ‘set print thread-events’, which controls printing of messages on thread start and exit.
- ‘set libthread-db-search-path path’, which lets the user specify which libthread_db to use if the default choice isn't compatible with the program.