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Just curiosity. Is there a good reason why the class URLConnection needs to have two different timeouts?

The connectTimeout is the maximum time in milliseconds to wait while connecting. Connecting to a server will fail with a SocketTimeoutException if the timeout elapses before a connection is established.

The readTimeout is the maximum time to wait for an input stream read to complete before giving up. Reading will fail with a SocketTimeoutException if the timeout elapses before data becomes available.

Can you give me a good reason why these two values should be different? Why a call would need more time for performing the connection rather than receiving some data (or viceversa)?

I am asking this because I have to configure these values and my idea is to set the same value for both.

Massimo
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3 Answers3

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Let's say server is busy and is configured to accept 'N' connection and all the connections are long runner and all of sudden you send in request, What should happen? Should you wait indefinitely or should you time out? That's connectTimeout.

While let's say your server turns brain dead service just accepting connection and doing nothing with it (or say server synchronously goes to db and does some time taking activity and server ends up with deadlock for e.g.) and on the other hand client keeps on waiting for the response, in this case what should client do? Should it wait indefinitely for response or should it timeout? That's read timeout.

SMA
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The connection timeout is how long you're prepared to wait to get some sort of response from the server. It's not particularly related to what it is that you're trying to achieve.

But suppose you had a service that would allow you to give it a large number, and have it return its prime factors. The server might take quite a while to generate the answer and send it to you.

You might well have clear expectations that the server would quickly respond to the connection: maybe even a delay of 5 seconds here tells you that the server is likely to be down. But the read timeout might need to be much higher: it might be a few minutes before you get to be able to read the server's answer to your query.

chiastic-security
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The connect time-out is the time-out in which you want a (in normal situations TCP) connection to be established. The default time-outs as specified in the internet RFCs and implemented by the various OSes are normally in the minute(s) range. But we know that if a server is available and reachable, it will respond in a matter of milli-seconds and otherwise not at all. A normal value would be a couple of seconds at a maximum.

The read timeout is the time in which the server is expected to respond after it received the incoming request. Read time-outs therefore depend on time within you expect the server to deliver the result. These are depending on the type of the request you are making and should be larger if the processing requires some time or the server may be very busy in some situations. Especially if you do a retry after a read time-out, it is best to put the read time-outs not too low, normally a factor 3-4 times the expected time.

Arie van Wijngaarden
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