On Tue, May 11, 2021 at 6:48 PM Dilip Kumar <dilipbal...@gmail.com> wrote: > > On Tue, May 11, 2021 at 4:50 PM Amul Sul <sula...@gmail.com> wrote: > > > > On Tue, May 11, 2021 at 4:13 PM Dilip Kumar <dilipbal...@gmail.com> wrote: > > > I might be missing something, but assume the behavior should be like this > > > > > > 1. If the state is getting changed from WALPROHIBIT_STATE_READ_WRITE > > > -> WALPROHIBIT_STATE_READ_ONLY, then as soon as the backend process > > > the barrier, we can immediately abort any read-write transaction(and > > > stop allowing WAL writing), because once we ensure that all session > > > has responded that now they have no read-write transaction then we can > > > safely change the state from WALPROHIBIT_STATE_GOING_READ_ONLY to > > > WALPROHIBIT_STATE_READ_ONLY. > > > > > > > Yes, that's what the current patch is doing from the first patch version. > > > > > 2. OTOH, if we are changing from WALPROHIBIT_STATE_READ_ONLY -> > > > WALPROHIBIT_STATE_READ_WRITE, then we don't need to allow the backend > > > to consider the system as read-write, instead, we should wait until > > > the shared state is changed to WALPROHIBIT_STATE_READ_WRITE. > > > > > > > I am sure that only not enough will have the same issue where > > LocalXLogInsertAllowed gets set the same as the read-only as described in > > my previous reply. > > Okay, but while browsing the code I do not see any direct if condition > based on the "LocalXLogInsertAllowed" variable, can you point me to > some references? > I only see one if check on this variable and that is in > XLogInsertAllowed() function, but now in XLogInsertAllowed() function, > you are already checking IsWALProhibited. No? >
I am not sure I understood this. Where am I checking IsWALProhibited()? IsWALProhibited() is called by XLogInsertAllowed() once when LocalXLogInsertAllowed is in a reset state, and that result will be cached in LocalXLogInsertAllowed and will be used in the subsequent XLogInsertAllowed() call. Regards, Amul
