On Mon, 3 Apr 2017 11:40:29 +0200, Tom DalPozzo <t.dalpozzo@xxxxxxxxx> wrote: >I saw that postgresql implementation makes big use of spin locks. >I was wondering if I should be concerned about possible starvation problem >because I looked around and couldn't find an absolute answer about if linux >spinlocks guarantee protection about starvation or not. I'm using ubuntu >16.04. > >I've noticed no problem so far, I'm just wondering. No form of locking can guarantee progress - starvation avoidance requires use of a wait-free arbitration method. Note that "wait-free" is not the same as "lock-less". Lock-less methods guarantee only that *some* thread can make progress, not that all threads will make progress. Any particular thread may starve under lock-less arbitration. There are a number of lock-less algorithms to choose from, but truely wait-free algorithms are complex and difficult to implement correctly. Outside of hard real-time systems they are quite rare. http://www.cs.technion.ac.il/~erez/Papers/wfquque-ppopp.pdf Spin locking is the optimal *locking* technique to use when conflicts are expected to occur relatively often, but the period of locking is relatively short [wrt to the unlocked period and for some respective definitions of "relatively"]. YMMV, George -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
