Re: file-locking and postmaster.pid

<blockquote type="CITE"><pre>
<font color="#000000">> > > You never need to reduce it to a shared lock.  On postmaster startup,</font>
<font color="#000000">> > > try to lock the sentinel byte (one byte past the end-of-file).  If you</font>
<font color="#000000">> > > can lock it, you know that no other postmaster has that byte locked.  If</font>
<font color="#000000">> > > you can't lock it, another postmaster is running. It is an atomic</font>
<font color="#000000">> > > operation. </font>
<font color="#000000">> > </font>
<font color="#000000">> > This doesn't work if the postmaster dies but a backend continues to run,</font>
<font color="#000000">> > which is arguably the most important case we need to protect against.</font>
<font color="#000000">> </font>
<font color="#000000">> I may be confused here, but I don't see the problem - byte-range locks</font>
<font color="#000000">> are not inherited across a fork.  A backend would never hold the lock, a</font>
<font color="#000000">> backend would never even look for the lock.</font>

<font color="#000000">Well, you are wrong here.  We _want_ every backend to hold a shared</font>
<font color="#000000">lock.  We need to stop a postmaster from starting if there is a backend</font>
<font color="#000000">running that was started by a no-longer-running postmaster.</font>
</pre></blockquote><pre>

</pre> Oh... didn't know that.  How is that accomplished now? There must be some code beside the pid file check.<br
/><br/>             -- Korry<br /><br />