Updated multiple modules to utilize gevent for concurrency, ensuring compatibility with gevent-based WSGI servers. This includes replacing threading.Thread and threading.Event with gevent.spawn and gevent.event.Event, respectively, to prevent blocking and improve performance during I/O operations.
- Refactored SandboxBuilder, Sandbox, CommandFuture, and DockerDemuxer to use gevent.
- Added detailed docstrings explaining the changes and benefits of using gevent primitives.
This change enhances the responsiveness and efficiency of the application in a gevent environment.