fix: make shutdown more graceful (#97)

* fix: make shutdown more graceful

* chore: move health shutdown first

* chore: also for http

Author: aaron-steinfeld

platform-grpc-service-framework/src/main/java/org/hypertrace/core/serviceframework/grpc/GrpcPlatformServiceContainer.java

@@ -1,6 +1,7 @@
 package org.hypertrace.core.serviceframework.grpc;
 
 import static io.grpc.Deadline.after;
+import static java.util.Objects.nonNull;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.concurrent.TimeUnit.SECONDS;
 
@@ -46,7 +47,7 @@
 @Slf4j
 abstract class GrpcPlatformServiceContainer extends PlatformService {
 
-  private List<ConstructedServer> servers;
+  private List<ConstructedServer> servers = Collections.emptyList();
   private final List<PlatformPeriodicTaskDefinition> taskDefinitions = new LinkedList<>();
   private final List<ScheduledFuture<?>> scheduledFutures = new LinkedList<>();
   private ScheduledExecutorService periodicTaskExecutor;
@@ -187,13 +188,15 @@ private void awaitServerTermination(ConstructedServer constructedServer) {
 
   @Override
   protected void doStop() {
-    this.scheduledFutures.forEach(future -> future.cancel(true));
     healthStatusManager.enterTerminalState();
-    grpcChannelRegistry.shutdown(after(10, SECONDS));
+    this.scheduledFutures.forEach(future -> future.cancel(true));
     this.servers.forEach(
         constructedServer ->
             ServerManagementUtil.shutdownServer(
                 constructedServer.getServer(), constructedServer.getName(), after(30, SECONDS)));
+    if (nonNull(grpcChannelRegistry)) {
+      grpcChannelRegistry.shutdown(after(10, SECONDS));
+    }
   }
 
   @Override

platform-http-service-framework/src/main/java/org/hypertrace/core/serviceframework/http/StandAloneHttpPlatformServiceContainer.java

@@ -48,8 +48,8 @@ protected void doStart() {
   @Override
   protected void doStop() {
     log.info("Stopping service {}", this.getServiceName());
-    grpcChannelRegistry.shutdown(after(10, SECONDS));
     this.container.stop();
+    grpcChannelRegistry.shutdown(after(10, SECONDS));
   }
 
   @Override