Fiber refactorings

java/algorithm/src/test/java/org/apache/arrow/algorithm/search/TestParallelSearcher.java

@@ -79,7 +79,7 @@ public void shutdown() {
   @MethodSource("getComparatorName")
   public void testParallelIntSearch(ComparatorType comparatorType, int threadCount)
       throws ExecutionException, InterruptedException {
-    threadPool = Executors.newFixedThreadPool(threadCount);
+    threadPool = Executors.newVirtualThreadPerTaskExecutor();
     try (IntVector targetVector = new IntVector("targetVector", allocator);
         IntVector keyVector = new IntVector("keyVector", allocator)) {
       targetVector.allocateNew(VECTOR_LENGTH);
@@ -118,7 +118,7 @@ public void testParallelIntSearch(ComparatorType comparatorType, int threadCount
   @MethodSource("getComparatorName")
   public void testParallelStringSearch(ComparatorType comparatorType, int threadCount)
       throws ExecutionException, InterruptedException {
-    threadPool = Executors.newFixedThreadPool(threadCount);
+    threadPool = Executors.newVirtualThreadPerTaskExecutor();
     try (VarCharVector targetVector = new VarCharVector("targetVector", allocator);
         VarCharVector keyVector = new VarCharVector("keyVector", allocator)) {
       targetVector.allocateNew(VECTOR_LENGTH);

java/flight/flight-core/src/main/java/org/apache/arrow/flight/FlightServer.java

@@ -312,11 +312,9 @@ public FlightServer build() {
         grpcExecutor = null;
       } else {
         exec =
-            Executors.newCachedThreadPool(
-                // Name threads for better debuggability
-                new ThreadFactoryBuilder()
-                    .setNameFormat("flight-server-default-executor-%d")
-                    .build());
+            Executors.newThreadPerTaskExecutor(Thread.ofVirtual()
+            					     .name("flight-server-default-executor-", 0)
+            					     .factory());
         grpcExecutor = exec;
       }
 

java/flight/flight-core/src/test/java/org/apache/arrow/flight/TestFlightGrpcUtils.java

@@ -52,7 +52,7 @@ public void setup() throws IOException {
     allocator = new RootAllocator(Integer.MAX_VALUE);
     final NoOpFlightProducer producer = new NoOpFlightProducer();
     final ServerAuthHandler authHandler = ServerAuthHandler.NO_OP;
-    final ExecutorService exec = Executors.newCachedThreadPool();
+    final ExecutorService exec = Executors.newVirtualThreadPerTaskExecutor();
     final BindableService flightBindingService =
         FlightGrpcUtils.createFlightService(allocator, producer, authHandler, exec);
 

java/flight/flight-core/src/test/java/org/apache/arrow/flight/perf/TestPerf.java

@@ -85,7 +85,7 @@ public static void main(String[] args) throws Exception {
   public void throughput() throws Exception {
     final int numRuns = 10;
     ListeningExecutorService pool =
-        MoreExecutors.listeningDecorator(Executors.newFixedThreadPool(4));
+        MoreExecutors.listeningDecorator(Executors.newVirtualThreadPerTaskExecutor());
     double[] throughPuts = new double[numRuns];
 
     for (int i = 0; i < numRuns; i++) {

java/flight/flight-integration-tests/src/test/java/org/apache/arrow/flight/integration/tests/IntegrationTest.java

@@ -103,10 +103,9 @@ void testScenario(String scenarioName) throws Exception {
     TestBufferAllocationListener listener = new TestBufferAllocationListener();
     try (final BufferAllocator allocator = new RootAllocator(listener, Long.MAX_VALUE)) {
       final ExecutorService exec =
-          Executors.newCachedThreadPool(
-              new ThreadFactoryBuilder()
-                  .setNameFormat("integration-test-flight-server-executor-%d")
-                  .build());
+      	  Executors.newThreadPerTaskExecutor(Thread.ofVirtual()
+            					     .name("integration-test-flight-server-executor-", 0)
+            					     .factory());
       final FlightServer.Builder builder =
           FlightServer.builder()
               .executor(exec)

java/flight/flight-sql-jdbc-core/src/main/java/org/apache/arrow/driver/jdbc/ArrowFlightConnection.java

@@ -158,6 +158,7 @@ ArrowFlightSqlClientHandler getClientHandler() {
   synchronized ExecutorService getExecutorService() {
     return executorService =
         executorService == null
+        // Refactoring this would require defining a new custom thread factory class
             ? Executors.newFixedThreadPool(
                 config.threadPoolSize(), new DefaultThreadFactory(getClass().getSimpleName()))
             : executorService;

java/flight/flight-sql/src/test/java/org/apache/arrow/flight/sql/example/FlightSqlExample.java

@@ -165,7 +165,7 @@ public class FlightSqlExample implements FlightSqlProducer, AutoCloseable {
   public static final String DB_NAME = "derbyDB";
   private final String databaseUri;
   // ARROW-15315: Use ExecutorService to simulate an async scenario
-  private final ExecutorService executorService = Executors.newFixedThreadPool(10);
+  private final ExecutorService executorService = Executors.newVirtualThreadPerTaskExecutor();
   private final Location location;
   protected final PoolingDataSource<PoolableConnection> dataSource;
   protected final BufferAllocator rootAllocator = new RootAllocator();

java/gandiva/src/test/java/org/apache/arrow/gandiva/evaluator/ProjectorTest.java

@@ -126,7 +126,7 @@ private void testMakeProjectorParallel(ConfigurationBuilder.ConfigOptions config
     // build projectors in parallel choosing schema at random
     // this should hit the same cache entry thus exposing
     // any threading issues.
-    ExecutorService executors = Executors.newFixedThreadPool(16);
+    ExecutorService executors = Executors.newVirtualThreadPerTaskExecutor();
 
     IntStream.range(0, 1000)
         .forEach(
@@ -348,7 +348,7 @@ public void testDivZeroParallel() throws GandivaException, InterruptedException
     ExpressionTree expr = TreeBuilder.makeExpression("divide", args, c);
     List<ExpressionTree> exprs = Lists.newArrayList(expr);
 
-    ExecutorService executors = Executors.newFixedThreadPool(16);
+    ExecutorService executors = Executors.newVirtualThreadPerTaskExecutor();
 
     AtomicInteger errorCount = new AtomicInteger(0);
     AtomicInteger errorCountExp = new AtomicInteger(0);

java/memory/memory-core/src/test/java/org/apache/arrow/memory/TestAccountant.java

@@ -46,21 +46,16 @@ public void multiThread() throws InterruptedException {
     Thread[] threads = new Thread[numberOfThreads];
 
     for (int i = 0; i < numberOfThreads; i++) {
-      Thread t =
-          new Thread() {
-
-            @Override
-            public void run() {
-              try {
-                for (int i = 0; i < loops; i++) {
-                  ensureAccurateReservations(parent);
-                }
-              } catch (Exception ex) {
-                ex.printStackTrace();
-                fail(ex.getMessage());
-              }
-            }
-          };
+      Thread t = Thread.ofVirtual(() -> {
+        try {
+          for (int i = 0; i < loops; i++) {
+            ensureAccurateReservations(parent);
+          }
+        } catch (Exception ex) {
+          ex.printStackTrace();
+          fail(ex.getMessage());
+        }
+      });
       threads[i] = t;
       t.start();
     }

java/performance/src/main/java/org/apache/arrow/algorithm/search/ParallelSearcherBenchmarks.java

@@ -67,7 +67,7 @@ public void prepare() {
       targetVector.allocateNew(VECTOR_LENGTH);
       keyVector = new IntVector("key vector", allocator);
       keyVector.allocateNew(1);
-      threadPool = Executors.newFixedThreadPool(numThreads);
+      threadPool = Executors.newVirtualThreadPerTaskExecutor();
 
       for (int i = 0; i < VECTOR_LENGTH; i++) {
         targetVector.set(i, i);