Java socket timeout during read

Question

What happens if a client connected through a Socket has a bad lag ? Let's say i call socket.read() from the TCP server, and the client writes some stuff on the network pipe, but his connection is laging for 1 or 2 minutes. What will happen ? Will the read fail ? Or will it wait ?

I'm not sure if it's even possible, but i'm playing online chess on FICS server and sometimes it seems to happen from my point of view (I'm only a user of this chess server).

I'm asking this because i'm working on an online game and i'd like to handle such cases one way or another. But first I need to know if:

it can happen
it can be detected

Thanks

Adamski · Accepted Answer · 2011-07-11 22:48:16Z

2

I'd advise not relying solely on setting the SO_TIMEOUT variable but rather add application-level heartbeats between your client and server. If either the client or server does not receive a heartbeat message within a specified time (e.g. within twice the heartbeat frequency) it should sever the connection, and in the client's case attempt a reconnect.

Using a heartbeat mechanism also allows you to measure the lag by monitoring the delay in receiving heartbeat messages on each end.

answered Jul 11, 2011 at 22:48

Adamski

54.8k15 gold badges121 silver badges153 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Joel Over a year ago

i'm just thinking... it's too bad it was not included in plain TCP

Adamski Over a year ago

Yes it is frustrating but I can understand why it's not part of the protocol, as different applications have different requirements.

Lukas Knuth · Accepted Answer · 2011-07-11 21:19:49Z

1

The read()-method will block. But there is the setSoTimeout()-method which can be used to set a timeout that can be handled.

answered Jul 11, 2011 at 21:19

Lukas Knuth

25.8k16 gold badges87 silver badges114 bronze badges

2 Comments

Joel Over a year ago

I'm aware of this option but how can it help distinguishing a lag from an absence of activity ?

Lukas Knuth Over a year ago

I don't think you can. You can buffer a lag using the Timeout and if there is no response, you'll need to assume there isn't anything coming in from the client.

berni · Accepted Answer · 2012-07-19 10:53:32Z

0

Actually, using setSoTimeout() might be a bit misleading. When you use it in such manner:

Socket sock = new Socket(host, port);
sock.setSoTimeout(3000); // 3 seconds timeout

The constructor initiates the connect(), while timeout haven't been set. Instead of expected 3 second timeout you get the default one. To get the desired timeout you can do it following way:

SocketAddress sockaddr = new InetSocketAddress(host, port);
Socket sock = new Socket();
sock.connect(sockaddr, 3000); // 3 seconds timeout

answered Jul 19, 2012 at 10:53

berni

1,9751 gold badge19 silver badges16 bronze badges

Collectives™ on Stack Overflow

Java socket timeout during read

3 Answers 3

2 Comments

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related