On Fri, Nov 21, 2025 at 9:17 AM Zhijie Hou (Fujitsu) <[email protected]> wrote: > > On Thursday, November 13, 2025 12:56 PM Zhijie Hou (Fujitsu) > <[email protected]> wrote: > > > > I have been thinking if there a way to avoid holding > ReplicationSlotControlLock > exclusively in ReplicationSlotsComputeRequiredXmin() because that could cause > lock contention when many slots exist and advancements occur frequently. > > Given that the bug arises from a race condition between slot creation and > concurrent slot xmin computation, I think another way is that, we acquire the > ReplicationSlotControlLock exclusively only during slot creation to do the > initial update of the slot xmin. In ReplicationSlotsComputeRequiredXmin(), we > still hold the ReplicationSlotControlLock in shared mode until the global slot > xmin is updated in ProcArraySetReplicationSlotXmin(). This approach prevents > concurrent computations and updates of new xmin horizons by other backends > during the initial slot xmin update process, while it still permits concurrent > calls to ReplicationSlotsComputeRequiredXmin(). >
Yeah, this seems to work. > Here is an update patch for this approach on HEAD. > Thanks for the patch. Sawada-San, are you planning to look into this? Otherwise, I can take care of it. -- With Regards, Amit Kapila.
