<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=us-ascii"> <meta name="Generator" content="Microsoft Exchange Server"> <style></style> </head> <body> <meta content="text/html; charset=UTF-8"> <style type="text/css" style="">  </style> <div dir="ltr"> <div id="x_divtagdefaultwrapper" dir="ltr" style="font-size:12pt; color:#000000; font-family:Calibri,Helvetica,sans-serif"> <p>I had my focus on the child (main daemon process), therefore the term went backward parent and grand-parent. Sorry, if that caused confusion, but let's go with your definitions.</p> <p><br> </p> <p>Thank you for the explanation and pointing out the steps! Especially 1. makes it much clearer than the list described here <a href="https://www.freedesktop.org/software/systemd/man/daemon.html" class="x_OWAAutoLink" id="LPlnk384058">https://www.freedesktop.org/software/systemd/man/daemon.html</a>, which only mention that P' shall call exit(). chrony is probably not making sure of 1., were P should wait until P' has exited. Now that you mentioned sysv semantics is old I come across an option in chrony which will not fork. I shall probably try using that instead.</p> <p><br> </p> <p>Best Regards,</p> <div id="x_Signature"> <div name="x_divtagdefaultwrapper" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:; margin:0"> Christopher Wong <div><br> </div> </div> </div> </div> <hr tabindex="-1" style="display:inline-block; width:98%"> <div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Lennart Poettering <lennart@poettering.net><br> <b>Sent:</b> Monday, October 31, 2022 11:43:17 AM<br> <b>To:</b> Christopher Wong<br> <b>Cc:</b> systemd-devel@lists.freedesktop.org<br> <b>Subject:</b> Re: [systemd-devel] Warning "Supervising process..." due to SIGCHLD from grand-parent</font> <div> </div> </div> </div> <font size="2"><span style="font-size:10pt;"> <div class="PlainText">On Mo, 31.10.22 11:40, Lennart Poettering (lennart@poettering.net) wrote:<br> <br> > This is almost certainly a bug in chrony. If you use Type=forking,<br> > then the process that systemd forks off (let's call it "P") should<br> > wait until all of the below holds:<br> ><br> > 1. The middle child P' has exited<br> > 2. The grandchild (and main daemon process) P'' is running<br> > 3. The PID file has been successfully written to contain the PID of P''.<br> <br> BTW, let me add an explanation, *why* this is needed: if they leave<br> P'' running for a bit longer, then there's a race: if for some reason<br> the deamon ends up failing shortly after starting up there is a race<br> if P' or P'' die first. If P'' dies first, then the service manager<br> will never see its SIGCHLD and cannot determine there was a<br> failure. If P' dies first then all is good, as the P'' SIGCHLD will be<br> properly collected by the service manager.<br> <br> But anyway, it's 2022, chrony being stuck in sysv semantics is<br> sad. Use sd_notify().<br> <br> Lennart<br> <br> --<br> Lennart Poettering, Berlin<br> </div> </span></font> </body> </html>