Log Message: ----------- Handle impending sinval queue overflow by means of a separate signal (SIGUSR1, which we have not been using recently) instead of piggybacking on SIGUSR2-driven NOTIFY processing. This has several good results: the processing needed to drain the sinval queue is a lot less than the processing needed to answer a NOTIFY; there's less contention since we don't have a bunch of backends all trying to acquire exclusive lock on pg_listener; backends that are sitting inside a transaction block can still drain the queue, whereas NOTIFY processing can't run if there's an open transaction block. (This last is a fairly serious issue that I don't think we ever recognized before --- with clients like JDBC that tend to sit with open transaction blocks, the sinval queue draining mechanism never really worked as intended, probably resulting in a lot of useless cache-reset overhead.) This is the last of several proposed changes in response to Philip Warner's recent report of sinval-induced performance problems. Modified Files: -------------- pgsql-server/src/backend/commands: async.c (r1.110 -> r1.111) (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/async.c.diff?r1=1.110&r2=1.111) pgsql-server/src/backend/postmaster: postmaster.c (r1.393 -> r1.394) (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/postmaster/postmaster.c.diff?r1=1.393&r2=1.394) pgsql-server/src/backend/storage/ipc: sinval.c (r1.62 -> r1.63) (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/storage/ipc/sinval.c.diff?r1=1.62&r2=1.63) sinvaladt.c (r1.54 -> r1.55) (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/storage/ipc/sinvaladt.c.diff?r1=1.54&r2=1.55) pgsql-server/src/backend/tcop: postgres.c (r1.413 -> r1.414) (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/tcop/postgres.c.diff?r1=1.413&r2=1.414) pgsql-server/src/include/commands: async.h (r1.23 -> r1.24) (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/commands/async.h.diff?r1=1.23&r2=1.24) pgsql-server/src/include/storage: pmsignal.h (r1.6 -> r1.7) (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/storage/pmsignal.h.diff?r1=1.6&r2=1.7) sinval.h (r1.33 -> r1.34) (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/storage/sinval.h.diff?r1=1.33&r2=1.34)
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