How to set timeout on client socket connection?

Question

I am trying to set the timeout of a connection on the client socket in Java. I have set the connection timeout to 2000 milliseconds, i.e:

this.socket.connect(this.socketAdd, timeOut);

This I am trying on a web application. When a user makes a request, I am passing values to socket server, but if I don't receive any response in 5 secs the socket should disconnect.

But in my case the whole request is getting submitted once again. Can any one please tell me where am I going wrong?

I want to cut the socket connection, if I don't get any response in 5 secs. How can I set it? Any sample code would help.

score 63 · Answer 1 · edited Jul 26 '22 at 03:43

63

You can try the follwoing:

Socket client = new Socket();   
client.connect(new InetSocketAddress(hostip, port_num), connection_time_out);

edited Jul 26 '22 at 03:43

informatik01

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answered Jan 27 '12 at 05:27

xyz

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This helped me for a timeout when the server doesn't exist, or is refusing connection. – anisbet Jun 06 '13 at 16:00
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btw, `connection_time_out` is in milliseconds – lightswitch05 Nov 08 '17 at 15:50

score 37 · Answer 2 · answered Jun 06 '13 at 16:23

37

To put the whole thing together:

Socket socket = new Socket();
// This limits the time allowed to establish a connection in the case
// that the connection is refused or server doesn't exist.
socket.connect(new InetSocketAddress(host, port), timeout);
// This stops the request from dragging on after connection succeeds.
socket.setSoTimeout(timeout);

answered Jun 06 '13 at 16:23

anisbet

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Shouldn't the SoTimeout be set before you enter the blocking operation ? – Lukas Hanacek Sep 21 '21 at 07:10

score 20 · Answer 3 · edited Feb 27 '13 at 19:09

20

What you show is a timeout for the connection, this will timeout if it cannot connect within a certain time.

Your question implies you want a timeout for when you are already connected and send a request, you want to timeout if there is no response within a certain amount of time.

Presuming you mean the latter, then you need to timeout the socket.read() which can be done by setting SO_TIMEOUT with the Socket.setSoTimeout(int timeout) method. This will throw an exception if the read takes longer than the number of milliseconds specified. For example:

this.socket.setSoTimeout(timeOut);

An alternative method is to do the read in a thread, and then wait on the thread with a timeout and close the socket if it timesout.

edited Feb 27 '13 at 19:09

Gray

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answered Apr 12 '11 at 08:57

Jim Morris

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Does "soTimeout" consider TCP acks? Let's say I send some data at time 't' and receive an acknowledgement from server at time 't' + 10. Nothing is received from the server after this ack. If "soTimeout" was set to 20 on my client , then will TCP layer consider the connection as closed at 't'+20 or at 't'+30. – kunjbhai Jun 19 '19 at 13:07
In case TCP will consider the connection closed at 't'+20 then yes setting "soTimeout" is same as reading on separate thread and timing out the thread otherwise it's not. This distinction is important as in case of TCP keep-alive acks are sent by server periodically to keep the connection alive. read from socket will never return because of keep-alive ack packets and so a tcp connection might break despite connection being active with server. – kunjbhai Jun 19 '19 at 13:17

How to set timeout on client socket connection?

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