问题
I have a single non-blocking socket sending udp packets to multiple targets and receiving responses from all of them on the same socket. I'm reading in a dedicated thread but writes (sendto) can come from several different threads.
Is this a safe without any additional synchronization? Do I need to write while holding a mutex? Or, do writes need to come from the same thread and I need a queue?
回答1:
The kernel will synchronize access to underlying file descriptor for you, so you don't need a separate mutex. There would be a problem with this approach if you were using TCP, but since we are talking about UDP this should be safe, though not necessarily best way.
回答2:
You can write to the socket from a single or multiple threads. If you write to a socket from multiple threads, they should be synchronized with a mutex. If instead your threads place their messages in a queue and a single thread pulls from the queue to do the writes, reads and writes to/from the queue should be protected by a mutex.
Reading and writing to the same socket from different threads won't interfere with each other.
来源：https://stackoverflow.com/questions/11212390/linux-socket-using-multiple-threads-to-send