Reduce Raft threshold to 2048

This can now go lower, since Raft snapshotting is more efficient. The
upside is that few logs will need be replayed when a node restarts,
which will result in shorter startup times. We may be able to go even
lower -- Consul defaults to 1024.

The downside is more Snapshotting, which pauses the system during that
time. But the pause times should be very short.

cmd/rqlited/flags.go

@@ -457,7 +457,7 @@ func ParseFlags(name, desc string, build *BuildInfo) (*Config, error) {
 	flag.DurationVar(&config.RaftHeartbeatTimeout, "raft-timeout", time.Second, "Raft heartbeat timeout")
 	flag.DurationVar(&config.RaftElectionTimeout, "raft-election-timeout", time.Second, "Raft election timeout")
 	flag.DurationVar(&config.RaftApplyTimeout, "raft-apply-timeout", 10*time.Second, "Raft apply timeout")
-	flag.Uint64Var(&config.RaftSnapThreshold, "raft-snap", 8192, "Number of outstanding log entries that trigger snapshot and Raft log compaction")
+	flag.Uint64Var(&config.RaftSnapThreshold, "raft-snap", 2048, "Number of outstanding log entries that trigger snapshot and Raft log compaction")
 	flag.DurationVar(&config.RaftSnapInterval, "raft-snap-int", 30*time.Second, "Snapshot threshold check interval")
 	flag.DurationVar(&config.RaftLeaderLeaseTimeout, "raft-leader-lease-timeout", 0, "Raft leader lease timeout. Use 0s for Raft default")
 	flag.BoolVar(&config.RaftStepdownOnShutdown, "raft-shutdown-stepdown", true, "If leader, stepdown before shutting down. Enabled by default")