[GitHub] [tinkerpop] divijvaidya commented on a change in pull request #1418: TINKERPOP-2550 Fixed bug in java Client initialization

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divijvaidya commented on a change in pull request #1418:
URL: https://github.com/apache/tinkerpop/pull/1418#discussion_r617508796



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File path: gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/Client.java
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@@ -511,19 +515,24 @@ protected Connection chooseConnection(final RequestMessage msg) throws TimeoutEx
          */
         @Override
         protected void initializeImplementation() {
+            // use a special executor here to initialize the Host instances as the worker thread pool may be
+            // insufficiently sized for this task and the parallel initialization of the ConnectionPool. if too small
+            // tasks may be schedule in such a way as to produce a deadlock: TINKERPOP-2550
+            //
+            // the cost of this single threaded executor here should be fairly small because it is only used once at
+            // initialization and shutdown. since users will typically construct a Client once for the life of their
+            // application there shouldn't be tons of thread pools being created and destroyed.
+            final BasicThreadFactory threadFactory = new BasicThreadFactory.Builder().namingPattern("gremlin-driver-init-%d").build();
+            final ExecutorService hostExecutor = Executors.newSingleThreadExecutor(threadFactory);

Review comment:
       starting and shutting down executor is an expensive operation which will impact the client start up/shut down time which will impact use cases when customers have short running clients such as in AWS Lambda. Is there an alternative approach that can avoid this?




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