On Wed, Dec 29, 2021 at 11:31 AM Andres Freund <and...@anarazel.de> wrote:
> Hi, > > On 2021-12-27 16:40:28 -0800, SATYANARAYANA NARLAPURAM wrote: > > > Yet another problem is that if we are in XlogInsert() that means we are > > > holding the buffer locks on all the pages we have modified, so if we > add a > > > hook at that level which can make it wait then we would also block any > of > > > the read operations needed to read from those buffers. I haven't > thought > > > what could be better way to do this but this is certainly not good. > > > > > > > Yes, this is a problem. The other approach is adding a hook at > > XLogWrite/XLogFlush? > > That's pretty much the same - XLogInsert() can trigger an > XLogWrite()/Flush(). > > I think it's a complete no-go to add throttling to these places. It's quite > possible that it'd cause new deadlocks, and it's almost guaranteed to have > unintended consequences (e.g. replication falling back further because > XLogFlush() is being throttled). > > I also don't think it's a sane thing to add hooks to these places. It's > complicated enough as-is, adding the chance for random other things to > happen > during such crucial operations will make it even harder to maintain. > Andres, thanks for the comments. Agreed on this based on the previous discussions on this thread. Could you please share your thoughts on adding it after SyncRepWaitForLSN()? > > Greetings, > > Andres Freund >
