Multiple threads reading from same socket.

Hi,

Is it fine if i have a single server fd which is read by multiple threads ?
Like i will have a one-to-many server and the recv is called in multiple threads (since there is no connect/accept prob with one to many server). Also will a blocking and non-blocking fd make a difference in this case?

Actually I have randomly tried this which works ok, but I am extremely skeptical. If there is some mutex lock inside recv, then i might not achieve any gain at all.

Darshan.

Hi -

1. Yes, any arbitrary thread may read any open socket at any time.

2. Yes, any thread that reads a blocking socket will block until there is data to be read.

3. No, one thread blocking on a read will not affect any other thread; nor affect the socket.

4. If there are *multiple* threads blocking, waiting to read from the *same* socket ... that's bad

5. In TCP/IP sockets, you cannot absolutely guarantee that *any* single read will return all the data you expect in a single call. It might take multiple reads to get all the data. This might wreak havoc with your "multiple threads reading/writing to the same socket" scenario if you're not careful.

Hi,

Thanks a lot for the answer.

Further,

4. If there are *multiple* threads blocking, waiting to read from the *same* socket ... that's bad
Yes, you are right. But I have other threads to do the normal chores of the application. And so it should be fine.

5. In TCP/IP sockets, you cannot absolutely guarantee that *any* single read will return all the data you expect in a single call. It might take multiple reads to get all the data. This might wreak havoc with your "multiple threads reading/writing to the same socket" scenario if you're not careful.
Ok. I am currently using SCTP. So every read fetches me a full message.

Regards,
Darshan.