Socket and multi-threading

  • Thread starter Thread starter Mahesh Devjibhai Dhola [MVP]
  • Start date Start date
M

Mahesh Devjibhai Dhola [MVP]

Hi,

Socket class documentation says that it is not thread safe. We understand
that if do simultaneous sends on ONE socket then it will be a problem (or
simultaneous receive). Can we create TWO threads on OUR OWN such that one
will do SEND and one will do RECEIVE using the SAME socket reference? This
means that two threads WILL BE in the same SOCKET object - one doing receive
and one doing send. We know we can use asynchronous calls on the socket to
achieve this but whether we can do this using our own threads. Any pointers
to official documentation that shows that this is permissible?

Thanks in advance,
Regards,
Mahesh
 
[Removing cross-posts]

TCP/IP sockets are full duplex - which means you can send and receive at the
same time.

-vj
 
Mahesh said:
Hi,

Socket class documentation says that it is not thread safe. We understand
that if do simultaneous sends on ONE socket then it will be a problem (or
simultaneous receive). Can we create TWO threads on OUR OWN such that one
will do SEND and one will do RECEIVE using the SAME socket reference? This
means that two threads WILL BE in the same SOCKET object - one doing receive
and one doing send. We know we can use asynchronous calls on the socket to
achieve this but whether we can do this using our own threads. Any pointers
to official documentation that shows that this is permissible?
Click to expand...


If you perform synchronized use of the socket by using thread locks (that is perform a
sending operation with one thread, after the other thread has finished reading), then I
suppose it is OK. However why are you using the Socket class itself for this?


In a book I am currently reading about .NET networking, stream socket communication is
performed in the style:

(get the connection Socket)
get a NetworkStream/create a NetworkStream with the Socket object
create a BinaryWriter and a BinaryReader with the NetworkStream

use the BinaryReader and BinaryWriter for network I/O

Call methods Close() of BinaryReader, BinaryWriter, NetworkStream, (Socket) in turn.
 
In your example the two threads will be executing different functions on the
same socket instance; they wlll use two different buffers (send and receive),
they will never block each other, hence you can use it.

As a side note, creating 2 threads to manage a socket is a sure way to kill
your application performance when n context of reasonably high number of
users. I'd recommend looking into async IO. IOCP is far more efficient way of
dealing with a problem.
 
You should be able to use a Monitor to lock one thread (Monitor.Enter(Me) and
Monitor.Wait(Me)) to ensure the second thread is finished (use
Monitor.Enter(Me) and Monitor.Pulse(Me) and Monitor.Exit(Me) in the second
class.
 
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