web service slowdown

Question

I have a web service slowdown. My (web) service is in gsoap & managed C++. It's not IIS/apache hosted, but speaks xml. My client is in .NET The service computation time is light (<0.1s to prepare reply). I expect the service to be smooth, fast and have good availability. I have about 100 clients, response time is 1s mandatory. Clients have about 1 request per minute. Clients are checking web service presence by tcp open port test. So, to avoid possible congestion, I turned gSoap KeepAlive to false. Until there everything runs fine : I bearly see connections in TCPView (sysinternals)

New special synchronisation program now calls the service in a loop. It's higher load but everything is processed in less 30 seconds. With sysinternals TCPView, I see that about 1 thousands connections are in TIME_WAIT. They slowdown the service and It takes seconds for the service to reply, now.

Could it be that I need to reset the SoapHttpClientProtocol connection ? Someone has TIME_WAIT ghosts with a web service call in a loop ?

Answer 1

Sounds like you aren't closing the connection after the call and opening new connections on each request. Either close the connection or reuse the open connections.

Answer 2

Be very careful with the implementations mentioned above. There are serious problems with them.

1. The implementation described in yakkowarner.blogspot.com/2008/11/calling-web-service-in-loop.html (COMMENT ABOVE):

   PROBLEM: All your work will be be wiped out the next time you regenerate the web service using wsdl.exe and you are going to forget what you did not to mention that this fix is rather hacky relying on a message string to take action.

2. The implementation described in forums.asp.net/t/1003135.aspx (COMMENT ABOVE):

   PROBLEM: You are selecting an endpoint between 5000 and 65535 so on the surface this looks like a good idea. If you think about it there is no way (at least none I can think of) that you could reserve ports to be used later. How can you guarantee that the next port on your list is not currently used? You are sequentially picking up ports to use and if some other application picks a port that is next on your list then you are hosed. Or what if some other application running on your client machine starts using random ports for its connections - you would be hosed at UNPREDICTABLE points in time. You would RANDOMLY get an error message like "remote host can't be reached or is unavailable" - even harder to troubleshoot.

Although I can't give you the right solution to this problem, some things you can do are:

1. Try to minimize the number of web service requests or spread them out more over a longer period of time
2. For your type of app maybe web services wasn't the correct architecture - for something with 1ms response time you should be using a messaging system - not a web service
3. Set your OS's number of connections allowed to 65K using the registry as in Windows
4. Set you OS's time that sockets remain in TIME_WAIT to some lower number (this presents its own list of problems)