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Hi Hirak<o:p></o:p>,<br>
<br>
In your scenario, the hanging on the client side is not a bug (but
yes, it is not user-friendly).<br>
<br>
Here is the description about MPI_Comm_connect in the MPI 3.0
standard.<br>
<blockquote type="cite">
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<p><span style="font-size: 11.000000pt; font-family:
'CMR10'">If the named port does not exist (or has been
closed), </span><span style="font-size: 11.000000pt;
font-family: 'CMSS10'">MPI</span><span style="font-size:
11.000000pt; font-family: 'CMTT10'">_</span><span style="font-size: 11.000000pt; font-family: 'CMSS10'">COMM</span><span style="font-size: 11.000000pt; font-family: 'CMTT10'">_</span><span style="font-size: 11.000000pt; font-family: 'CMSS10'">CONNECT
</span><span style="font-size: 11.000000pt; font-family:
'CMR10'">raises
an error of class </span><span style="font-size:
10.000000pt; font-family: 'CMSS10'">MPI</span><span style="font-size: 10.000000pt; font-family: 'CMTT10'">_</span><span style="font-size: 10.000000pt; font-family: 'CMSS10'">ERR</span><span style="font-size: 10.000000pt; font-family: 'CMTT10'">_</span><span style="font-size: 10.000000pt; font-family: 'CMSS10'">PORT</span><span style="font-size: 11.000000pt; font-family: 'CMR10'">.
</span></p>
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> run_good in your example.<br>
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<p><span style="font-size: 11.000000pt; font-family:
'CMR10'">If the port exists, but does not have a pending
</span><span style="font-size: 11.000000pt; font-family:
'CMSS10'">MPI</span><span style="font-size: 11.000000pt;
font-family: 'CMTT10'">_</span><span style="font-size:
11.000000pt; font-family: 'CMSS10'">COMM</span><span style="font-size: 11.000000pt; font-family: 'CMTT10'">_</span><span style="font-size: 11.000000pt; font-family: 'CMSS10'">ACCEPT</span><span style="font-size: 11.000000pt; font-family: 'CMR10'">,
the connection
attempt will eventually time out after an
implementation-defined time, or succeed when
the server calls </span><span style="font-size:
11.000000pt; font-family: 'CMSS10'">MPI</span><span style="font-size: 11.000000pt; font-family: 'CMTT10'">_</span><span style="font-size: 11.000000pt; font-family: 'CMSS10'">COMM</span><span style="font-size: 11.000000pt; font-family: 'CMTT10'">_</span><span style="font-size: 11.000000pt; font-family: 'CMSS10'">ACCEPT</span><span style="font-size: 11.000000pt; font-family: 'CMR10'">.
In the case of a time out, </span><span style="font-size: 11.000000pt; font-family: 'CMSS10'">MPI</span><span style="font-size: 11.000000pt; font-family: 'CMTT10'">_</span><span style="font-size: 11.000000pt; font-family: 'CMSS10'">COMM</span><span style="font-size: 11.000000pt; font-family: 'CMTT10'">_</span><span style="font-size: 11.000000pt; font-family: 'CMSS10'">CONNECT
</span><span style="font-size: 11.000000pt; font-family:
'CMR10'">raises an error of class </span><span style="font-size: 10.000000pt; font-family: 'CMSS10'">MPI</span><span style="font-size: 10.000000pt; font-family: 'CMTT10'">_</span><span style="font-size: 10.000000pt; font-family: 'CMSS10'">ERR</span><span style="font-size: 10.000000pt; font-family: 'CMTT10'">_</span><span style="font-size: 10.000000pt; font-family: 'CMSS10'">PORT</span><span style="font-size: 11.000000pt; font-family: 'CMR10'">.
</span></p>
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<title>MPI: A Message-Passing Interface Stand</title>
> This is the run_bad case, the "<span style="font-size:
11.000000pt; font-family: 'CMR10'">eventually time out</span>" is
implementation dependent
<title>: A Message-Passing Interface Standard</title>
. However, I just glanced over the code, it seems MPICH currently
does not handle user-specified timeout through the info argument. I
will look into code and keep you updated.<br>
<br>
Min<br>
<br>
<div class="moz-cite-prefix">On 5/11/16 11:39 PM, Roy, Hirak wrote:<br>
</div>
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<div class="WordSection1">
<p class="MsoNormal">Hi mpich team,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am using MPICH 3.0.4 sock with dynamic
connection (accept/connect).<o:p></o:p></p>
<p class="MsoNormal">I am facing issues with the following
scenario, when there is a race condition in MPI_Comm_connect.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here is the case <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo1"><!--[if !supportLists]--><span style="mso-list:Ignore">1><span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]-->Server opens a port, writes the
port info in a file, calls MPI_Comm_accept<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo1"><!--[if !supportLists]--><span style="mso-list:Ignore">2><span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]-->Client1 & Client2 reads the
port information from file and each client calls
MPI_Comm_connect<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo1"><!--[if !supportLists]--><span style="mso-list:Ignore">3><span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]-->Server accepts one client,
disconnects, closes the port, exit<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo1"><!--[if !supportLists]--><span style="mso-list:Ignore">4><span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]-->One of the client successfully
connects, disconnects, exit<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l1 level1 lfo1"><!--[if !supportLists]--><span style="mso-list:Ignore">5><span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]-->The other client hangs in
MPI_Comm_connect<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">If you do the following steps, you can
reproduce the issue<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span style="mso-list:Ignore">1><span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]-->Please set compiler and
installation path of MPICH in makefile<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span style="mso-list:Ignore">2><span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]-->make : compiles<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><!--[if !supportLists]--><span style="mso-list:Ignore">3><span style="font:7.0pt
"Times New Roman"">
</span></span><!--[endif]-->make run_bad<o:p></o:p></p>
<p class="MsoListParagraph"><o:p> </o:p></p>
<p class="MsoNormal">I have noticed that in case client calls
MPI_Comm_connect after the port is closed, the connect calls
successfully terminates with error (make run_good).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Please let me know whether it is a bug or
not.<o:p></o:p></p>
<p class="MsoNormal">Please also let me know if the connect call
can be configured with a timeout or not.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Hirak<o:p></o:p></p>
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