Insert CHECK_FOR_INTERRUPTS in sleep

Author: knizhnik

multimaster.c

@@ -342,6 +342,7 @@ void MtmSleep(timestamp_t interval)
 
     while (nanosleep(&ts, &rem) < 0) { 
         Assert(errno == EINTR);
+		CHECK_FOR_INTERRUPTS();
         ts = rem;
     }
 }

pglogical_receiver.c

@@ -714,7 +714,9 @@ void MtmStartReceiver(int nodeId, bool dynamic)
 	worker.bgw_main_arg = Int32GetDatum(nodeId);
 	if (dynamic) { 
 		BackgroundWorkerHandle *handle;
-		RegisterDynamicBackgroundWorker(&worker, &handle);
+		if (!RegisterDynamicBackgroundWorker(&worker, &handle)) { 
+			elog(WARNING, "Failed to start background worker, please increase max_worker_processes configuration parameter (current value is %d)", max_worker_processes);
+		}
 	} else {
 		RegisterBackgroundWorker(&worker);
 	}