Is Indy TIdTCPClient suitable for local TCP/IP connections?

Question

I need to connect to a device on the local network, using a TCP/IP connection. When I use a TIdTCPClient, all works well, except one thing:

If the connection is not available, it takes about 18-20 seconds before I get a timeout. The property ConnectTimeout has no effect, no matter what values I set. It always takes the same amount of time before a timeout.

This answer mentions long delay times for a timeout, and I am wondering if that's related to the Indy components?

I have to find out if the connection cannot be established very quickly, let's say within 1 second at most.

Is there a way to do this using Indy, or do I need to use different components / a different approach?

(I'm using the Indy 10 version that shipped with Delphi 2009)

EDIT:
I followed the instructions to upgrade Indy to the latest version in this post.

Still the same, it now consistently takes 22 seconds until TCPClient.Connect returns when there is no connection. ConnectTimeout and/or ReadTimeout seem to have no influence on this.

Answer 1

I had the same exact problem. Check out this StackOverflow post.

In short, because Indy threads are blocking, you will need to make a threaded process. Then in the primary application create a timer which will terminate the thread if it has not done what it is supposed to do in the time given.

After I implemented this is worked great.

Answer 2

ConnectTimeout works correctly for 2010 and XE. Perhaps you can update your Indy version to the latest (its free). I have a function that does 'quick check' connects, just to check availability of the device and those timeouts are 5 seconds without problems (in both 2010 and XE).

Answer 3

With a default TCP client connect timeout (not specifically set) and a read timeout of 1 second, using Delphi 2010 and the latest Indy version, a local connection (using localhost as the host name) times out in 1 second. So this is definitely not a Delphi/Indy issue. BTW, this gives me an EIdSocketError ("socket error # 10061 connection refused").