Andres Freund <and...@anarazel.de> writes: > I think it could exascerbate the issue. Parag reported ~7k connections on a > 128 core machine. The buffer replacement logic in < 16 tries to lock the old > and new lock partitions at once. That can lead to quite bad "chains" of > dependent lwlocks, occasionally putting all the pressure on a single lwlock. > With 7k waiters on a single spinlock, higher frequency of wakeups will make it > much more likely that the process holding the spinlock will be put to sleep. > This is greatly exacerbated by the issue fixed in a4adc31f690, once the > waitqueue is long, the spinlock will be held for an extended amount of time.
Yeah. So what's the conclusion? Leave it alone? Commit to HEAD only? regards, tom lane