Re: Relation extension scalability

<div dir="ltr"><div class="gmail_extra"><br /><div class="gmail_quote">On Fri, Mar 11, 2016 at 12:04 AM, Petr Jelinek
<spandir="ltr"><<a href="mailto:petr@2ndquadrant.com" target="_blank">petr@2ndquadrant.com</a>></span>
wrote:</div><divclass="gmail_quote"><br /></div><div class="gmail_quote">Thanks for looking..</div><div
class="gmail_quote"><br/><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc
solid;padding-left:1ex">Thoselook good. The patch looks good in general now. I am bit scared by the lockWaiters * 20 as
itcan result in relatively big changes in rare corner cases when for example a lot of backends were waiting for lock on
relationand suddenly all try to extend it. I wonder if we should clamp it to something sane (although what's sane today
mightbe small in couple of years).</blockquote></div><div class="gmail_extra"><br /></div>But in such condition when
allare waiting on lock, then at a time only one waiter will get the lock and that will easily count the lock waiter and
extendin multiple of that. And we also have the check that if any waiter get the lock it will first check in FSM that
anybodyelse have added one block or not..</div><div class="gmail_extra"><br /></div><div class="gmail_extra">And other
waiterwill not get lock unless first waiter extend all blocks and release the locks.</div><div class="gmail_extra"><br
/></div><divclass="gmail_extra">One possible case is as soon as we extend the blocks new requester directly find in FSM
anddon't come for lock, and old waiter after getting lock don't find in FSM, But IMHO in such cases, also its good that
otherwaiter also extend more blocks (because this can happen when request flow is very high).</div><div
class="gmail_extra"><br/></div><div class="gmail_extra"><br /></div><div class="gmail_extra">-- <br /><div
class="gmail_signature"><divdir="ltr"><span style="color:rgb(80,0,80);font-size:12.8px">Regards,</span><br
style="color:rgb(80,0,80);font-size:12.8px"/><span style="color:rgb(80,0,80);font-size:12.8px">Dilip Kumar</span><br
style="color:rgb(80,0,80);font-size:12.8px"/><span style="color:rgb(80,0,80);font-size:12.8px">EnterpriseDB: </span><a
href="http://www.enterprisedb.com/"style="color:rgb(17,85,204);font-size:12.8px"
target="_blank">http://www.enterprisedb.com</a><br/></div></div></div></div>