Fixed prometheus service exit without starting

main/src/main/java/com/ongres/pgio/main/Main.java

@@ -31,7 +31,6 @@ import com.ongres.pgio.main.stats.serializer.StatSerializer;
 import com.ongres.pgio.main.version.Version;
 
 import fi.iki.elonen.NanoHTTPD;
-
 import joptsimple.OptionException;
 import joptsimple.OptionParser;
 import joptsimple.OptionSet;
@@ -48,6 +47,7 @@ import java.time.Duration;
 import java.time.Instant;
 import java.util.Optional;
 import java.util.Scanner;
+import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
@@ -138,9 +138,12 @@ public class Main {
     return message;
   }
   
-  private static void runPrometheusService(Config config) throws IOException {
+  private static void runPrometheusService(Config config) throws Exception {
     PrometheusService service = new PrometheusService(config);
     service.start(NanoHTTPD.SOCKET_READ_TIMEOUT, false);
+    while (true) {
+      TimeUnit.MICROSECONDS.sleep(20);
+    }
   }
 
   private static void runCollector(Config config) throws Exception, InterruptedException {