On Sun, 2010-05-16 at 16:53 +0100, Simon Riggs wrote: > > > > Attached patch rearranges the walsender loops slightly to fix the above. > > XLogSend() now only sends up to MAX_SEND_SIZE bytes (== XLOG_SEG_SIZE / > > 2) in one round and returns to the main loop after that even if there's > > unsent WAL, and the main loop no longer sleeps if there's unsent WAL. > > That way the main loop gets to respond to signals quickly, and we also > > get to update the shared memory status and PS display more often when > > there's a lot of catching up to do. > > > > Comments > > 8MB at a time still seems like a large batch to me. > > libpq is going to send it in smaller chunks anyway, so I don't see the > importance of trying to keep the batch too large. It just introduces > delay into the sending process. We should be sending chunks that matches > libpq better.
More to the point the logic will fail if XLOG_BLCKSZ > PQ_BUFFER_SIZE because it will send partial pages. Having MAX_SEND_SIZE > PQ_BUFFER_SIZE is pointless, as libpq currently stands. -- Simon Riggs www.2ndQuadrant.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
