[Boost-bugs] [Boost C++ Libraries] #6698: WSASend synchronous send/close failure with latency

Subject: [Boost-bugs] [Boost C++ Libraries] #6698: WSASend synchronous send/close failure with latency
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-03-17 15:26:49

#6698: WSASend synchronous send/close failure with latency
-----------------------------------------+----------------------------------
 Reporter:  thrawy@…                     |       Owner:  chris_kohlhoff
     Type:  Bugs                         |      Status:  new           
Milestone:  To Be Determined             |   Component:  asio          
  Version:  Boost 1.47.0                 |    Severity:  Problem       
 Keywords:  syncrhonous WSASend latency  |  
-----------------------------------------+----------------------------------
 After making a synchronous socket call (send(), write() or close()) that
 returns success, if the calling thread exits quickly, on connections with
 ~500 ms latency, the operation doesn't actually take place. (With little
 latency the problem does not occur.)

 With the following code snippet, send() returns the correct size for the
 buffer and ec.value() remains 0. However, using wireshark at the remote,
 the data never arrives.

 {{{
 boost::system::error_code ec;
 size_t nWritten = m_sock->send( <some data>, ec );
 assert( nWritten == <data size> );
 assert( !ec.value() );
 m_sock->close( ec );
 assert( !ec.value() );

 m_io_service->stop();
 m_thread->join();
 }}}
 This occurs both with linger on and off. I was able to verify this on
 several different systems running 32 and 64 bit windows 7.  By putting an
 assert in socket_ops.ipp immediately after its call to WSASend() I was
 able to verify that it returned success and WSAGetLastError() returned 0.

 If I add a brief ::Sleep(100) call immediately after the socket calls
 fixes the problem and the data is transmitted and received at the other
 end.

 My thought is that this is a Windows error - when a socket is created
 using WSASocket() with WSA_FLAG_OVERLAPPED set (as asio does), a call to
 WSASend() with the overlapped arguments set to 0 isn't truly performed
 synchronously.

 I couldn't find this bug previously reported anywhere, if it is I
 apologize.

 Thanks
 Hugh

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6698>
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