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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Correct – there is no way to purge the pipe. It must be emptied by the reactor loop internally. So you must allow the loop to run. Note that the
logic to prevent more bytes from being written to the pipe when there should already be a notify in the pipe is defeated when you keep purging the notification queue.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">-Steve<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Jack Wong [mailto:pandawkx@163.com]
<br>
<b>Sent:</b> Monday, November 28, 2016 7:40 PM<br>
<b>To:</b> Steve Huston <shuston@riverace.com><br>
<b>Cc:</b> ace-bugs@list.isis.vanderbilt.edu<br>
<b>Subject:</b> Re:Re: [ace-bugs] [ACE]: [calling purge_pending_notifications() before notify() leads to dead-lock]<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">Steve:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">"let the reactor event loop run and read things from the notify pipe" may be not a good idea.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">Notify pipe has limited buffer . When put too much bytes to the write end,soon buffer will be full and write operation will be blocked.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">As checking the current implement codes, I found that the designer may intend to keep only one message in the pipe to avoid buffer becoming full and keep plenty of
messages in the queue.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">The problem is you can purge messages in the queue but you can not easily purge messages in the pipe.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">-Jack Wong<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">At 2016-11-29 00:43:07, "Steve Huston" <<a href="mailto:shuston@riverace.com">shuston@riverace.com</a>> wrote:<br>
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<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">Thank you for the problem info and research into it.
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">The easiest way to resolve this is to let the reactor event loop run and read things from the notify pipe.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">-Steve<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">On Nov 28, 2016, at 3:12 AM, Jack Wong <<a href="mailto:pandawkx@163.com">pandawkx@163.com</a>> wrote:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">ACE VERSION: 6.3.0<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">(this bug still exists in version 6.4.0)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">Our test codes looks like this:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">1:while (true)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">2:{<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">3: reactor()->purge_pending_notifications(xxx);<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">4: reactor()->notify(xxx);<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">5:}<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">after a while , we found dead-lock occurs at line 4.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="ZH-CN" style="font-size:10.5pt;color:black">−−−−−−−−−−−−−−−−−−−−−−−−−</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">I check the code and found that :<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">purge_pending_notifications can only purge message in notify queue<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">messages in pipe can not be purged<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">so calling notify() after purge_pending_notifications() can always leads one message be write to pipe<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">So when I keep calling like this , soon buffer of pipe will full and notify() will be blocked , then dead-lock occurs<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="ZH-CN" style="font-size:10.5pt;color:black">−−−−−−−−−−−−−−−−−−−−−−−−−</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">we are using this two interfaces building important functions of our application<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">we will appreciate it if this bug being fixed soon<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="ZH-CN" style="font-size:10.5pt;color:black">−−−−−−−−−−−−−−−−−−−−−−−−−</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">poor English, sorry!<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black">_______________________________________________<br>
ace-bugs mailing list<br>
<a href="mailto:ace-bugs@list.isis.vanderbilt.edu">ace-bugs@list.isis.vanderbilt.edu</a><br>
<a href="http://list.isis.vanderbilt.edu/cgi-bin/mailman/listinfo/ace-bugs">http://list.isis.vanderbilt.edu/cgi-bin/mailman/listinfo/ace-bugs</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
<p> <o:p></o:p></p>
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