fix: use newFixedThreadPool

worker/src/main/scala/WorkerService.scala

@@ -71,7 +71,7 @@ class WorkerService(
     implicit val executionContext: ExecutionContextExecutor =
       scala.concurrent.ExecutionContext.fromExecutor(
         java.util.concurrent.Executors
-          .newCachedThreadPool()
+          .newFixedThreadPool(15)
       )
 
     def sorted(path: Path) = Future {
@@ -84,15 +84,19 @@ class WorkerService(
     Future {
       try {
         logger.info(s"[WorkerServer] Sort ($request)")
-
+        logger.info(
+          s"[WorkerServer] thread number in sort1 : ${java.lang.Thread.activeCount()}"
+        )
         Await.result(
           Future.traverse(inputFiles.toList)(sorted)(
             GenericBuildFrom[File, File],
             executionContext
           ),
           scala.concurrent.duration.Duration.Inf
         )
-
+        logger.info(
+          s"[WorkerServer] thread number in sort2 : ${java.lang.Thread.activeCount()}"
+        )
         logger.info("[WorkerServer] Sorted")
 
         promise.success(new SortReply())
@@ -114,7 +118,7 @@ class WorkerService(
     implicit val executionContext: ExecutionContextExecutor =
       scala.concurrent.ExecutionContext.fromExecutor(
         java.util.concurrent.Executors
-          .newCachedThreadPool()
+          .newFixedThreadPool(15)
       )
 
     val workers: Seq[WorkerMetadata] = request.workers
@@ -154,15 +158,19 @@ class WorkerService(
     Future {
       try {
         logger.info(s"[WorkerServer] Partition ($request)")
-
+        logger.info(
+          s"[WorkerServer] thread number in partition1 : ${java.lang.Thread.activeCount()}"
+        )
         Await.result(
           Future.traverse(inputFiles.toList)(partition)(
             GenericBuildFrom[File, Seq[File]],
             executionContext
           ),
           scala.concurrent.duration.Duration.Inf
         )
-
+        logger.info(
+          s"[WorkerServer] thread number in partition2 : ${java.lang.Thread.activeCount()}"
+        )
         logger.info("[WorkerServer] Partitioned")
 
         promise.success(new PartitionReply())
@@ -182,7 +190,7 @@ class WorkerService(
     implicit val executionContext: ExecutionContextExecutor =
       scala.concurrent.ExecutionContext.fromExecutor(
         java.util.concurrent.Executors
-          .newCachedThreadPool()
+          .newFixedThreadPool(15)
       )
 
     val workers: Seq[WorkerMetadata] = request.workers
@@ -210,14 +218,19 @@ class WorkerService(
               .map(_._2)
 
             logger.info(s"[WorkerServer] Sending $chunk to $targetClients")
-
+            logger.info(
+              s"[WorkerServer] thread number in exchange before : ${java.lang.Thread.activeCount()}"
+            )
             Await.result(
               Future.traverse(targetClients)(_.saveBlock(chunk))(
                 GenericBuildFrom[WorkerClient, SaveBlockReply],
                 executionContext
               ),
               scala.concurrent.duration.Duration.Inf
             )
+            logger.info(
+              s"[WorkerServer] thread number in exchange end : ${java.lang.Thread.activeCount()}"
+            )
           })
         })