Worker thread(BeginGetRequestStream,BeginGetResponse) both sync

Worker thread(BeginGetRequestStream,BeginGetResponse) both sync

06-16-2008 9:28 AM |

Following code hangs forever,without visible reason,docs says HttpWebRequest utilize "worker thread" to do it's work,but it seems block UI thread anyway:

AutoResetEvent re = new AutoResetEvent(false);
IAsyncResult a_r= null;
a_r = r.BeginGetRequestStream(x => re.Set(), null);
re.WaitOne();//OK

using (var rs = r.EndGetRequestStream(a_r))
{
    rs.Write(...);
    a_r= r.BeginGetResponse(x => re.Set(), null);
}
re.WaitOne();//hangs forever

Thanks.

Re: Worker thread(BeginGetRequestStream,BeginGetResponse) both sync

06-18-2008 4:14 AM |

See http://silverlight.net/forums/t/18336.aspx

Re: Worker thread(BeginGetRequestStream,BeginGetResponse) both sync

06-18-2008 5:11 AM |

XASD:

What could be wrong?

Your call to BeginGetResponse is queued after the completion of your method, so it is never made due to the WaitOne. You're clearly trying to block until the web service call completes, so I'll save you a bunch of time, give up. Can't be done.

Re: Worker thread(BeginGetRequestStream,BeginGetResponse) both sync

06-18-2008 11:16 AM |

Please,clarify a little what does it means EndGetRequestStream()-«something needs to be done on the UI thread.»

Thanks a lot.

Re: Re: Worker thread(BeginGetRequestStream,BeginGetResponse) both sync

06-19-2008 7:08 AM |

Well, have a look at the code of EndGetResponse from Reflector:

AsyncHelper.BeginOnUI(delegate (object sendState) {
response = this.InternalEndGetResponse(asyncResult);
}, null);

As you can see, EndGetResponse will delegate the work to UI. If the UI thread is blocked by your "re", of course the browser will hang forever. So you must call re.Set before EndGetResponse.

Re: Re: Worker thread(BeginGetRequestStream,BeginGetResponse) both sync

06-19-2008 8:40 AM |

I'm talking about BeginGetResponse not EndGetResponse,why code above does not work? BeginGetResponse not have a chance to execute re.Set() in delegate.Why similar combination BeginGetRequestStream(x=>re.Set());re.WaitOne() work just fine and free UI thread for EndGetRequestStream(),but BeginGetResponse(x=>re.Set());re.WaitOne(); just hangs forever? EndGetResponse() will follow re.Wait(); and must have no problems with UI thread in my case.

...
re.WaitOne();//hangs forever
using (var rs = r.EndGetResponse(a_r))//must be executed just fine in my case,if previous line would not block "something"
{
}

Best wishes.

Re: Re: Re: Worker thread(BeginGetRequestStream,BeginGetResponse) both sync

06-20-2008 3:55 PM |

Thanks a lot,I see:-)