Re: TODO : Allow parallel cores to be used by vacuumdb [ WIP ] - Mailing list pgsql-hackers

<div class="WordSection1"><p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">On</span><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"></span><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">28October 2014 09:18, Amit Kapila Wrote,</span><p
class="MsoNormal"><spanstyle="font-size:10.0pt;font-family:"Tahoma","sans-serif""> </span><p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>Iam worried about the case if after setting
theinAbort flag,</span><p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>PQCancel()fails (returns error).</span><p
class="MsoNormal"><spanstyle="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">> </span><p
class="MsoNormal"><spanstyle="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>> If select(maxFd
+1, workerset, NULL, NULL, &tv); come out, we can know whether it came out because of cancel query and handle it
accordingly.</span><pclass="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>> </span><pclass="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">> </span><pclass="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>Yeah,it is fine for the case when
PQCancel()is successful, what</span><p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>ifit fails?</span><p
class="MsoNormal"><spanstyle="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>I think even if
selectcomes out due to any other reason, it will behave</span><p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>asif it came out due to Cancel, even though
actuallyCancel is failed,</span><p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">>howare planning to handle that
case?</span><pclass="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><pclass="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Ithink If PQcancel fails then also there is no
problem,because we are setting inAbort flag in handle_sigint handler, it means user have tried to terminate.</span><p
class="MsoNormal"><spanstyle="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><p
class="MsoNormal"><spanstyle="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">So in this case as well
wewill find that <b>inAbort </b>is set so we return error, and in error case we finally call <b>DisconnectDatabase</b>,
andin this function we will send the <b>PQcancel</b> for all active connection and then only we disconnect.</span><p
class="MsoNormal"><spanstyle="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> </span><p
class="MsoNormal"><spanstyle="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">Regards,</span><p
class="MsoNormal"><spanstyle="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">DIlip</span></div>