I have already asked a similar question here: WCF Service calling an external web service results in timeouts in heavy load environment but I've got a better idea now as to what's happening so posting a new question.
This is what is happening:
.NET client sends multiple requests at the same time to a WCF service (if it helps - I'm replicating this scneario by using Visual Studio Load Tests)
The client has got a "sendTimeout" set to 5 seconds
The WCF service receives it and start processing it. The processing involves sending a request to an external service which could take about 1 second to come back with a response
This is where I think the problem is: the client has sent many requests to the service and since the service is still busy processing the concurrent requests, some of the reqeusts from the client are timing out after 5 seconds
I have tried the following:
Changed the InstanceContextMode to PerCall
Increased the values of maxConcurrentCalls & maxConcurrentInstances
Increased the value of connectionManagement.maxconnection in machine.config
But none of that seems to be making any difference. Does anyone has any idea how can I ensure that I don't run into this timeout issue?
OK, you say WCF and that is not enough. What binding are you using and where are you hosting it? If you are using IIS, the could be different underlying problem than self-hosting.
The likely reason is the small number of ThreadPool size. You can use ThreadPool.SetMaxThreads() to change this but beware this is a sensitive value. Have a look here.
Check out the following link:
http://weblogs.asp.net/paolopia/archive/2008/03/23/wcf-configuration-default-limits-concurrency-and-scalability.aspx
I'm not sure what you're trying to achieve. Since the WCF service is doing a time consuming operation, you can't overload it and expect it to function. You can do the following (check the link about to set the following):
Increase the receiving capacity of the wcf service
Increase the send timeout of the service
Increase the send timeout of the client
Increase the receive timeout of the client
Limit the outgoing connections to the wcf service
The best and most robust option would be to configure and use MSMQ with the WCF service.
Related
I have a WCF SOAP service that receives too many synchronous requests from other systems
I am having problem when too many request comes at that time IIS Queue will not provide proper result and server memory and CPU usage is gone high and discard request or time out
I did a normal Load test (100 requests with 100 concurrent user) and the IIS started to discard the requests after the maximum queue length reach as well as all the request coming delays to provide the response and Other requests coming in are delayed until the first one either times out, or responds.
Below is server configuration
WCF application code is tested with Resharper tool and there is no object or memory dispose issue
Is there any settings for setup application pool or worker process to manage queue ?
Can i apply web garden in Application ?
Please help me to solve this issue
Thanks in Advance
We observed the following behavior on one of the servers hosting a WCF service on IIS 6.0:
The IIS log shows a high value for time-taken (> 100000)
The HTTP status code is 200
sc-win32-status code shows a value of 64
I found out that sc-win32-status code of 64 indicates "The specified network is no longer available"
Initially I suspected that it could be because of limits set on MinFileBytesPerSecond, which sets the minimum throughput rate that HTTP.sys enforces when sending data from the client to the server, and back from the server to the client.
But the value for sc-bytes and cs-bytes indicate that the amount of data is sent is within the range generally observed for the service.
Also note that the WCF service is hosted on four boxes and is load-balanced, but the problem occurs only one of the servers. (but not essentially on the same server). The problem is also intermittent.
Has anybody else encountered this error? Any clues about what could be wrong?
Update
Note: Observation on IIS 7.5 (IIS version does not really matter)
I was able to replicate the issue. The issue occurs if:
1. The WCF service takes a long time to respond
2. The client proxy times out before it receives a response from the server. In this case it leads to TimeoutException on the client.
3. The server keeps waiting for TCP ACK for the client, which it would never receive.
Hence a long timeout (TCP socket timeout (default value: 4 minutes) and sc-win32-status of 64
So essentially it appears that WCF code is taking a long time to respond and the client is timing out, what I observe in IIS log is just a symptom and not a problem.
The behavior you are describing will also occur if you exceed a WCF service's max sessions, calls or instances (depending on how you have your service instancecontext mode configured). If you observe the System.ServiceModel performance counters for %max concurrent sessions and/or %max concurrent calls (again depending on your service's instance context), you may see a correlation with the IIS log entries.
Note that these maxes can be configured in the service throttling behavior.
https://msdn.microsoft.com/en-us/library/vstudio/system.servicemodel.description.servicethrottlingbehavior(v=vs.100).aspx
I saw your question again and wanted to point out that I found a solution for this. It turned out to be this piece of code in the web.config:
<pages smartNavigation="true">
After turning this off I stopped receiving the same time-out errors. See also the answer here
IIS put the services into sleep to save recources.
Copied from here (WCF REST Service goes to sleep after inactivity)
The application pool hosting your service defines Idle Time-out property (advanced settings of app pool in IIS management console) which defaults to 20 minutes. If no request is received by the app pool within idle timeout the worker processes serving the pool is terminated. After receiving a new request the IIS must start the process again, the process must load application domain and all related assemblies, compile .svc file, run the service host and process the request.The solution can be increasing idle time-out but the meaning of this time-out is correct handling of server resources. If the process is not needed it should be stopped. Another ugly workaround is using some ping process (for example cron job or scheduled task on the server) which will regularly ping call some method on the service or page in the same application.
We are seeing random timeout issue when trying to invoke WCF Service through Classic ASP(VBScript). I verified WCF trace but don't see any error or warning. What is best way to debug the issue? We are using JSON response format.
First check your configuration values to see what the timeout is supposed to be, and that the client and server timeouts match.
Then check the server side logs so that you see if the responses are taking as long as the timeout.
Try to find a pattern:
Time of day
After a recycling
Heavy load
Number of clients / connections.
90% of the time I see this problem it is due to the WCF clients not being closed. The problem is that by default there are 10 WCF connections, they are used untill they get closed. So the first 10 go fast, the 11th must wait for one of the others to be available. This will be when it is closed or timesout.
In a Silverlight 4 app, I would like to increase the timeout for a specific RIA service load operation (not for all loads, just in a specific case). At Configuring the timeout for a WCF RIA Services call from a Silverlight 3 client I followed a link to instructions that purportedly would allow me to set the timeout.
It appeared to work fine (no compiler error, warning, exception, etc) except that the load operation still timed out early. It appears that with or without the code that modifies the endpoint the load operation is timing out after 2 minutes. There is an Opening event on the ChannelFactory which I subscribed to, and my handler was called at the start of the load operation, so that seems to confirm that the ChannelFactory is being used. Also I set all 4 timeout values (Receive, Open, Close, Send) to 10 minutes just to be sure that I wasn't setting the wrong one.
Why I am unable to actually change the timeout for the RIA load?
I discovered the problem was that multiple timeouts were in play. I was using an EntityFramework domain service for RIA, and I was getting an EntityFramework timeout. I was misinterpreting the source of the timeout as being from the RIA load until I noticed in the stack trace that the timeout was server side. I extended the allotted EntityFramework command timeout to fit my desired load behavior. I was able to confirm that after getting a reference to the channel factory for the domain context I could set the RIA client-side timeout.
NOTE TO SELF: a good way to troubleshoot a timeout is to start by setting it really short to confirm it is working as intended
I have 2 wcf services, 1 which polls the other service at regular interval.The service2 is hosted in no. of machines with the same configuration.
My problem is that whenever the poller service gets restarted, even though the service2 on other machines runs fine, i am not getting the response from those services (basically it gets timed out - getting SYSTEM.TimeOutException ). If I try to access the same service (service2) from some temp application (without restarting the service2) it gives response.
If I restart the service2, than it works fine, the service1 (poller service) gets the responses from all hosted services (Service2).
Dont know what is causing problem.
Regards,
Chirag
Attach VS to your wcf service which hangs. And find out if your connection is successful.
Do it with both services, so that you can debug the services at runtime.
If you're using a sessionful binding (netTcpBinding, wsHttpBinding), it's more than likely that you're not explicitly closing your client channel when you're done with it. This would cause the behavior you see, because the session takes a minute or so to time out if you don't explicitly close it, and the default max number of sessions is low (10)- the server will let new sessions stack up until old ones close. You can also adjust the service throttle on the server side binding to increase the max number of open sessions allowed, but you really should make sure your clients are getting cleaned up properly first.