client: register before restoring

Registration and restoring allocs don't share state or depend on each
other in any way (syncing allocs with servers is done outside of
registration).

Since restoring is synchronous, start the registration goroutine first.

For nodes with lots of allocs to restore or close to their heartbeat
deadline, this could be the difference between becoming "lost" or not.

client/client.go

@@ -442,6 +442,9 @@ func NewClient(cfg *config.Config, consulCatalog consul.CatalogAPI, consulServic
 		logger.Warn("batch fingerprint operation timed out; proceeding to register with fingerprinted plugins so far")
 	}
 
+	// Register and then start heartbeating to the servers.
+	c.shutdownGroup.Go(c.registerAndHeartbeat)
+
 	// Restore the state
 	if err := c.restoreState(); err != nil {
 		logger.Error("failed to restore state", "error", err)
@@ -456,9 +459,6 @@ func NewClient(cfg *config.Config, consulCatalog consul.CatalogAPI, consulServic
 		return nil, fmt.Errorf("failed to restore state")
 	}
 
-	// Register and then start heartbeating to the servers.
-	c.shutdownGroup.Go(c.registerAndHeartbeat)
-
 	// Begin periodic snapshotting of state.
 	c.shutdownGroup.Go(c.periodicSnapshot)