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Receiving request timeout even though connect timeout and read timeout is set to default (infinite)?
I tried to connect to a web service and received a SocketTimeoutException after approximately 20 seconds. The Tomcat server hosting the web service is down so the Exception is expected. However, I did not set the value of my ConnectTimeout and ReadTimeout. According to the documentation, the default values of these two are infinite.
One possibility for this is that the server I tried connecting to has its own timeout. But when my friend tried to connect to it using iOS, his connection timed out after approximately 1 minute and 15 seconds. If the server is the one issuing the timeout, our connection should have timed out at almost the same time. Please note that he is also using the default time out of iOS.
Why did my socket timed out so early when my connect and read timeout are set to infinite?
Is socket timeout different to connect and read timeout? If so, how is it different?
How can I know the value of my socket timeout? I am using HttpURLConnection.
Is there a way to set the socket timeout? How?
Below is a snippet of my code:
httpURLConnection = (HttpURLConnection) ((new URL("http://www.website.com/webservice")).openConnection());
httpURLConnection.setDoInput(isDoInput);
httpURLConnection.setDoOutput(isDoOutput);
httpURLConnection.setRequestMethod(method);
try
{
OutputStreamWriter writer = new OutputStreamWriter(httpURLConnection.getOutputStream());
writer.write("param1=value1");
writer.flush;
}catch(Exception e)
{
}
Why did my socket timed out so early when my connect and read timeout are set to infinite?
Code please.
Is socket timeout different to connect and read timeout? If so, how is it different?
SocketTimeoutException is a read timeout.
How can I know the value of my socket timeout? I am using HttpURLConnection.
HttpURLConnection.getReadTimeout(); also HttpURLConnection.getConnectTimeout().
Is there a way to set the socket timeout? How?
HttpURLConnection.setReadTimeout().
You have already cited all these methods in your original post. Why are you asking about them here?
Finally, I found what causing my timeout! It turns out that it is indeed the server who is causing my timeout. I doubt on this one at first because I am receiving a different timeout when using iOS which is more than 1 minute.
So here it is:
The operating system holding my Tomcat server is Windows. Windows' default number of retries for unanswered connection is 2. So when your first attempt to connect fails, you still have 2 retries left. The retries are all done internally. I'm not sure how the time for each retry is calculated but basically it's 3 + 6 + 12 = 21 seconds.
1st retry = 3 seconds
2nd retry = 6 seconds
3rd retry = 12 seconds
After the 3rd retry, your connection will be cut-off. Also, by that time, you already waited for 21 seconds.
Related
I have to call a web service that takes 40 seconds to respond. I'm in JBoss-EAP 6.4 and I use this code:
IService svc = service.getBasicHttpBindingIService();
[...]
((BindingProvider) svc).getRequestContext().put("com.sun.xml.ws.connect.timeout",timeout)
[...]
svc.processMessage(req);
When the timeout is less then 20000 (20 seconds), I get the expected exception:
HTTP transport error: java.net.SocketTimeoutException: connect timed out
If the timeout is bigger than 20000, i get another exeption after 20 second:
HTTP transport error: java.net.ConnectException: Connection timed out: connect
So, I can't get the response from the server (40 seconds to respond), I always get the exception. What kind of timeout I have to increase?
Why do you want the timeout to be 40 seconds? There are two timeouts represented by "com.sun.xml.internal.ws.connect.timeout" and "com.sun.xml.internal.ws.request.timeout". You could have been connected to the server, but the request is taking long to process in which case, the latter setting would take effect. Note: I believe these settings are for JBoss (I could be wrong, cross check it).
I am trying to create a java http server using tcp sockets. HTTP 1.1 has a timeout value that will enable the connection to be persistent and wait for a short while for possible data from the client. I am trying to implement this timer in my program by using:clientSocket.setSoTimeout(). Even though this will help to leave the connection open for a certain amount of time, but it will wait for that exact amount of time before allowing the next request to be read.
For example:
If timeout is set to 5 seconds,
Request 1 is read. Then the socket hangs and wait until 5 seconds is over.
Request 2 is read. The socket waits until 5 seconds is up again.
This proves to be a problem if my timeout is set to big values. This should not be the case as the request should be processed once it is received and the timeout should only expire only if no data is received throughout the specified duration.
Can anyone advise me on how I could resolve this?
Edit:
For people who face a similar problem, here is my solution:
Since the client waits until the timeout before receiving all the data, I guessed that the client does not know that all the data from the server has been received. Hence, I added a content-length field to the HTTP response packet. Now, my client no longer hangs after receiving the data. The setSoTimeout does indeed work as stated!
Ok, when you receive a connection, then please start a new Thread like this:
class ClientService extends Thread {
private final Socket clientSocket;
public ClientService(Socket clientSocket) {
this.clientSocket=clientSocket;
}
public void run() {
// do your work with the Socket clientSocket here
}
}
this is how then your server code should look like:
while (true) {
Socket clientSocket = server.accept();
new ClientService(clientSocket).start();
}
It will allow you to process responses without waiting for one another till it timeouts.
HTTP 1.1 has a timeout value that will enable the connection to be persistent and wait for a short while for possible data from the client.
Not really. It has a connection: keep-alive setting, which is the default behaviour, and it allows endpoints to close connections that aren't in use after a period of idleness, but it doesn't have a timeout property itself.
I am trying to implement this timer in my program by using:clientSocket.setSoTimeout().
This has nothing whatsoever to do with HTTP. It is a socket read timeout.
Even though this will help to leave the connection open for a certain amount of time, but it will wait for that exact amount of time before allowing the next request to be read.
No it won't. It will cause read methods to throw SocketTimeoutException if no data arrives within the timeout period. Nothing else.
For example:
If timeout is set to 5 seconds,
Request 1 is read. Then the socket hangs and wait until 5 seconds is over.
No it doesn't.
Request 2 is read. The socket waits until 5 seconds is up again.
No it doesn't. You've made all this up. It is fantasy.
This proves to be a problem if my timeout is set to big values.
It isn't a problem with any timeout values whether large or small, because it simply does not happen.
This should not be the case as the request should be processed once it is received and the timeout should only expire only if no data is received throughout the specified duration.
That is exactly what Socket.setSoTimeout() already does.
Your question is founded on a fallacy.
I though Spymemcached does attempt to reestablish connection to the server when this connection get lost.
But I am seeing something different; wondering what I misunderstand or what I do wrong. Here is some sample code:
MemcachedClient c=new MemcachedClient(AddrUtil.getAddresses("server:11211"));
while(true)
try {
System.out.println(c.get("hatsts"));
Thread.sleep(10000);
} catch(Exception e) {
e.printStackTrace();
}
It runs initially without problem. Then I pull the network plug. Subsequently, the client detects a network failure and throws following exception:
net.spy.memcached.OperationTimeoutException: Timeout waiting for value
But then, when i re-establish the network, the client does not recover and continues throwing the exception; even after 5 min. I tried SpyMemcached 2.10.6 and 2.9.0.
What am I missing?
The problem here is that because you pulled the network cable the tcp socket on you client still thinks the connection is valid. The tcp keepalive varies from operating system to operating system and can be as high as 30 minutes. As a result the application (in this case Spymemcached) is not notified that the connection is no longer valid by the tcp layer and therefore Spymemcached doesn't try to reconnect.
The way Spymemcached detects this situation is by counting the amount of consecutive operation timeouts. The last time I checked the default value was 99. Once this many ops time out then Spymemcached will reconnect. You can change this value in the ConnectionFactory if you want to set it to some other value. There's a function called getContinuousTimeout() which is where the Spymemcached gets 99 from by default. You can construct your own ConnectionFactory with the ConnectionFactoryBuilder.
Hopefully this is enough information to answer your question and get you going in the right direction. If not let me know and I can add some more details.
In my Java application I need to get the ping of multiple connections at once, I have tried using a thread for each connection and measuring the response time but they don't all seem to be correct.
Is there a thread safe way to measure the ping/response time of a connection? I am currently using:
Thread thread = new Thread(new Runnable() {
public void run(){
long start = System.currentTimeMillis();
someInetAddress.isReachable(5000);
long timeTaken = System.currentTimeMillis() - start;
}
});
However timeTaken doesn't seem to be correct as users with 150 ping are getting 5000 (probably more because it seems to have timed out)
Help is appreciated!
Keir
Edit: Okay found out that its due to Port 7 being closed for some people, is there any other way to ping them without them having to have Port 7 closed?
The isReachable() method works by trying to connect to TCP port 7 (echo). It doens't actually care whether port 7 is closed or not. All it cares about is whether there is a response of any kind to the connect. A ConnectException rates as isReachable = true, and it should take about the same amount of time as a successful connection, maybe even quicker. A connect timeout, host not reachable, etc, rate as false.
The method is advertised to use ICMP in very limited circumstances: you aren't on Windows and you have root privilege. In practice this never applies.
I'm issuing a socket connection, using the following snippet
Socket socket = new Socket();
InetSocketAddress endPoint = new InetSocketAddress("localhost", 1234);
try
{
socket.connect(endPoint, 30000);
}
catch (IOException e)
{
e.printStackTrace();
// Logging
}
The endpoint it is trying to connect to is offline, what I want it to do is to attempt to connect, and using the 30000ms timeout, wait for that period of time before it concludes a result
Currently, that 30000 parameter doesn't seem to be applied, as from the timestamp on my logging it appears that it is determining within 1 second that a connection failed.
How can I force the connect to wait for a set amount of time before giving up?
13:13:57,685 6235 DEBUG [Thread-7] - Unable to connect to [localhost:1234]
13:13:58,685 7235 DEBUG [Thread-7] - Unable to connect to [localhost:1234]
13:13:59,695 8245 DEBUG [Thread-7] - Unable to connect to [localhost:1234]
13:14:00,695 9245 DEBUG [Thread-7] - Unable to connect to [localhost:1234]
EDIT : The API does state Connects this socket to the server with a specified timeout value. A timeout of zero is interpreted as an infinite timeout. The connection will then block until established or an error occurs. however it appears I'm not experiencing such behaviour, or am not catering to it, most likely the latter
What you're getting here is correct. connect won't sit on a socket waiting until it sees a server, it will attempt to connect and wait for a response. if there is nothing to connect to, it returns. if there is something to connect to, it will wait timeout seconds for a response and fail if none is received.
You need to distinguish among several possible exception conditions.
ConnectException with the text 'connection refused', which means the host was up and reachable and nothing was listening at the port. This happens very quickly and cannot be subjected to a timeout.
NoRouteToHostException: this indicates a connectivity issue. Again it happens immediately and cannot be subjected to a timeout.
UnknownHostException: the host names cannot be resolved via DNS. This happens immediately, or rather after a generally short DNS delay, and cannot be subjected to a timeout.
ConnectException with any other text: this can indicate a failure to respond by the target system. Usually happens when firewalls are present. Can be subjected to a timeout.
You are doing the correct thing by calling Socket.connect() with a timeout parameter. If you don't do this, or if you specify a zero timeout, the default system timeout is used, which is of the order of 60-75 seconds depending on the platform. This is contrary to the Javadoc's statement about an 'infinite timeout', which is not correct. Also you cannot increase the timeout beyond this limit via Socket.connect() witha a timeout parameter. Alternatively you can use java.nio socket channels in non-blocking mode with a select() to administer the timeout for you, but you still can't increase the timeout beyond the platform default via this or any other method.
When the timeout occurs, a SocketTimeoutException exception is thrown which you do not catch and log. The IOException is fired when "an error occurs during the connection". The timeout is never applied because there's an error beforehand.
Edit: Just to clarify: TCP/IP as a suite has many specifics that could prevent a packet from reaching it's desired outcome (a SYN/ACK packet). If a computer responds to your SYN packet by an informing your application that the port is closed (i.e. there's no application running/listening there), it would fire an exception telling you that it is impossible to connect to that port. If you wish to send and re-send SYN packets either way with the knowledge that an application will come online listening on that port, this is done on a different network layer (and, as far as I know, is not accessible with Java out-of-the-box).
Try scocket.setSoTimeout(timeout) before connecting.