Reimplement finding open ports (#2629)

instrumentation/apache-camel-2.20/javaagent/src/test/groovy/io/opentelemetry/javaagent/instrumentation/apachecamel/RestCamelTest.groovy

@@ -33,7 +33,7 @@ class RestCamelTest extends AgentInstrumentationSpecification implements RetryOn
   }
 
   def setupSpecUnderRetry() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
     def app = new SpringApplication(RestConfig)
     app.setDefaultProperties(["restServer.port": port])
     server = app.run()

instrumentation/apache-camel-2.20/javaagent/src/test/groovy/io/opentelemetry/javaagent/instrumentation/apachecamel/SingleServiceCamelTest.groovy

@@ -38,7 +38,7 @@ class SingleServiceCamelTest extends AgentInstrumentationSpecification implement
   }
 
   def setupSpecUnderRetry() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
     address = new URI("http://localhost:$port/")
     def app = new SpringApplication(SingleServiceConfig)
     app.setDefaultProperties(["camelService.port": port])

instrumentation/apache-camel-2.20/javaagent/src/test/groovy/io/opentelemetry/javaagent/instrumentation/apachecamel/SqsCamelTest.groovy

@@ -46,7 +46,7 @@ class SqsCamelTest extends AgentInstrumentationSpecification {
      void initialize(AbstractApplicationContext applicationContext) {applicationContext.getBeanFactory().registerSingleton("localStack", sqs)}})
      server = app.run()**/
 
-    sqsPort = PortUtils.randomOpenPort()
+    sqsPort = PortUtils.findOpenPort()
     sqs = SQSRestServerBuilder.withPort(sqsPort).withInterface("localhost").start()
     println getClass().name + " SQS server started at: localhost:$sqsPort/"
 

instrumentation/apache-camel-2.20/javaagent/src/test/groovy/io/opentelemetry/javaagent/instrumentation/apachecamel/TwoServicesWithDirectClientCamelTest.groovy

@@ -39,8 +39,8 @@ class TwoServicesWithDirectClientCamelTest extends AgentInstrumentationSpecifica
   }
 
   def setupSpecUnderRetry() {
-    portOne = PortUtils.randomOpenPort()
+    portOne = PortUtils.findOpenPort()
-    portTwo = PortUtils.randomOpenPort()
+    portTwo = PortUtils.findOpenPort()
     def app = new SpringApplication(TwoServicesConfig)
     app.setDefaultProperties(["service.one.port": portOne, "service.two.port": portTwo])
     server = app.run()

instrumentation/apache-dubbo/apache-dubbo-2.7/testing/src/main/groovy/io/opentelemetry/instrumentation/apachedubbo/v2_7/AbstractDubboTest.groovy

@@ -52,7 +52,7 @@ abstract class AbstractDubboTest extends InstrumentationSpecification {
 
   def "test apache dubbo base #dubbo"() {
     setup:
-    def port = PortUtils.randomOpenPort()
+    def port = PortUtils.findOpenPort()
     protocolConfig.setPort(port)
 
     DubboBootstrap bootstrap = DubboBootstrap.getInstance()
@@ -121,7 +121,7 @@ abstract class AbstractDubboTest extends InstrumentationSpecification {
 
   def "test apache dubbo test #dubbo"() {
     setup:
-    def port = PortUtils.randomOpenPort()
+    def port = PortUtils.findOpenPort()
     protocolConfig.setPort(port)
 
     DubboBootstrap bootstrap = DubboBootstrap.getInstance()

instrumentation/aws-sdk/aws-sdk-1.11/testing/src/main/groovy/io/opentelemetry/instrumentation/awssdk/v1_11/AbstractSqsTracingTest.groovy

@@ -34,7 +34,7 @@ abstract class AbstractSqsTracingTest extends InstrumentationSpecification {
 
   def setupSpec() {
 
-    sqsPort = PortUtils.randomOpenPort()
+    sqsPort = PortUtils.findOpenPort()
     sqs = SQSRestServerBuilder.withPort(sqsPort).withInterface("localhost").start()
     println getClass().name + " SQS server started at: localhost:$sqsPort/"
 

instrumentation/couchbase/couchbase-testing/src/main/groovy/util/AbstractCouchbaseTest.groovy

@@ -31,7 +31,7 @@ abstract class AbstractCouchbaseTest extends AgentInstrumentationSpecification {
   static final PASSWORD = "password"
 
   @Shared
-  private int port = PortUtils.randomOpenPort()
+  private int port = PortUtils.findOpenPort()
 
   @Shared
   private String testBucketName = this.getClass().simpleName

instrumentation/dropwizard-testing/src/test/groovy/DropwizardTest.groovy

@@ -38,7 +38,7 @@ class DropwizardTest extends HttpServerTest<DropwizardTestSupport> implements Ag
     def testSupport = new DropwizardTestSupport(testApp(),
       null,
       ConfigOverride.config("server.applicationConnectors[0].port", "$port"),
-      ConfigOverride.config("server.adminConnectors[0].port", PortUtils.randomOpenPort().toString()))
+      ConfigOverride.config("server.adminConnectors[0].port", PortUtils.findOpenPort().toString()))
     testSupport.before()
     return testSupport
   }

instrumentation/grpc-1.5/testing/src/main/groovy/io/opentelemetry/instrumentation/grpc/v1_5/AbstractGrpcStreamingTest.groovy

@@ -65,7 +65,7 @@ abstract class AbstractGrpcStreamingTest extends InstrumentationSpecification {
         }
       }
     }
-    def port = PortUtils.randomOpenPort()
+    def port = PortUtils.findOpenPort()
     Server server = configureServer(ServerBuilder.forPort(port).addService(greeter)).build().start()
     ManagedChannelBuilder channelBuilder = configureClient(ManagedChannelBuilder.forAddress("localhost", port))
 

instrumentation/grpc-1.5/testing/src/main/groovy/io/opentelemetry/instrumentation/grpc/v1_5/AbstractGrpcTest.groovy

@@ -58,7 +58,7 @@ abstract class AbstractGrpcTest extends InstrumentationSpecification {
         responseObserver.onCompleted()
       }
     }
-    def port = PortUtils.randomOpenPort()
+    def port = PortUtils.findOpenPort()
     Server server = configureServer(ServerBuilder.forPort(port).addService(greeter)).build().start()
     ManagedChannelBuilder channelBuilder = configureClient(ManagedChannelBuilder.forAddress("localhost", port))
 
@@ -141,7 +141,7 @@ abstract class AbstractGrpcTest extends InstrumentationSpecification {
         responseObserver.onError(error)
       }
     }
-    def port = PortUtils.randomOpenPort()
+    def port = PortUtils.findOpenPort()
     Server server = configureServer(ServerBuilder.forPort(port).addService(greeter)).build().start()
     ManagedChannelBuilder channelBuilder = configureClient(ManagedChannelBuilder.forAddress("localhost", port))
 
@@ -227,7 +227,7 @@ abstract class AbstractGrpcTest extends InstrumentationSpecification {
         throw error
       }
     }
-    def port = PortUtils.randomOpenPort()
+    def port = PortUtils.findOpenPort()
     Server server = configureServer(ServerBuilder.forPort(port).addService(greeter)).build().start()
     ManagedChannelBuilder channelBuilder = configureClient(ManagedChannelBuilder.forAddress("localhost", port))
 
@@ -325,7 +325,7 @@ abstract class AbstractGrpcTest extends InstrumentationSpecification {
         responseObserver.onCompleted()
       }
     }
-    def port = PortUtils.randomOpenPort()
+    def port = PortUtils.findOpenPort()
     Server server
     server = configureServer(ServerBuilder.forPort(port)
       .addService(greeter)
@@ -466,7 +466,7 @@ abstract class AbstractGrpcTest extends InstrumentationSpecification {
         responseObserver.onNext(Helloworld.Response.getDefaultInstance())
       }
     }
-    def port = PortUtils.randomOpenPort()
+    def port = PortUtils.findOpenPort()
     Server server
     server = configureServer(ServerBuilder.forPort(port)
       .addService(greeter))

instrumentation/jedis/jedis-1.4/javaagent/src/test/groovy/JedisClientTest.groovy

@@ -15,7 +15,7 @@ import spock.lang.Shared
 class JedisClientTest extends AgentInstrumentationSpecification {
 
   @Shared
-  int port = PortUtils.randomOpenPort()
+  int port = PortUtils.findOpenPort()
 
   @Shared
   RedisServer redisServer = RedisServer.builder()

instrumentation/jedis/jedis-3.0/javaagent/src/test/groovy/Jedis30ClientTest.groovy

@@ -15,7 +15,7 @@ import spock.lang.Shared
 class Jedis30ClientTest extends AgentInstrumentationSpecification {
 
   @Shared
-  int port = PortUtils.randomOpenPort()
+  int port = PortUtils.findOpenPort()
 
   @Shared
   RedisServer redisServer = RedisServer.builder()

instrumentation/jsp-2.3/javaagent/src/test/groovy/JspInstrumentationBasicTests.groovy

@@ -44,7 +44,7 @@ class JspInstrumentationBasicTests extends AgentInstrumentationSpecification {
     baseDir = Files.createTempDirectory("jsp").toFile()
     baseDir.deleteOnExit()
 
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
 
     tomcatServer = new Tomcat()
     tomcatServer.setBaseDir(baseDir.getAbsolutePath())

instrumentation/jsp-2.3/javaagent/src/test/groovy/JspInstrumentationForwardTests.groovy

@@ -41,7 +41,7 @@ class JspInstrumentationForwardTests extends AgentInstrumentationSpecification {
     baseDir = Files.createTempDirectory("jsp").toFile()
     baseDir.deleteOnExit()
 
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
 
     tomcatServer = new Tomcat()
     tomcatServer.setBaseDir(baseDir.getAbsolutePath())

instrumentation/lettuce/lettuce-4.0/javaagent/src/test/groovy/LettuceAsyncClientTest.groovy

@@ -63,8 +63,8 @@ class LettuceAsyncClientTest extends AgentInstrumentationSpecification {
   RedisCommands<String, ?> syncCommands
 
   def setupSpec() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
-    incorrectPort = PortUtils.randomOpenPort()
+    incorrectPort = PortUtils.findOpenPort()
     dbAddr = HOST + ":" + port + "/" + DB_INDEX
     dbAddrNonExistent = HOST + ":" + incorrectPort + "/" + DB_INDEX
     dbUriNonExistent = "redis://" + dbAddrNonExistent

instrumentation/lettuce/lettuce-4.0/javaagent/src/test/groovy/LettuceSyncClientTest.groovy

@@ -50,8 +50,8 @@ class LettuceSyncClientTest extends AgentInstrumentationSpecification {
   RedisCommands<String, ?> syncCommands
 
   def setupSpec() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
-    incorrectPort = PortUtils.randomOpenPort()
+    incorrectPort = PortUtils.findOpenPort()
     dbAddr = HOST + ":" + port + "/" + DB_INDEX
     dbAddrNonExistent = HOST + ":" + incorrectPort + "/" + DB_INDEX
     dbUriNonExistent = "redis://" + dbAddrNonExistent

instrumentation/lettuce/lettuce-5.0/javaagent/src/test/groovy/LettuceAsyncClientTest.groovy

@@ -66,8 +66,8 @@ class LettuceAsyncClientTest extends AgentInstrumentationSpecification {
   RedisCommands<String, ?> syncCommands
 
   def setupSpec() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
-    incorrectPort = PortUtils.randomOpenPort()
+    incorrectPort = PortUtils.findOpenPort()
     dbAddr = PEER_NAME + ":" + port + "/" + DB_INDEX
     dbAddrNonExistent = PEER_NAME + ":" + incorrectPort + "/" + DB_INDEX
     dbUriNonExistent = "redis://" + dbAddrNonExistent

instrumentation/lettuce/lettuce-5.0/javaagent/src/test/groovy/LettuceReactiveClientTest.groovy

@@ -39,7 +39,7 @@ class LettuceReactiveClientTest extends AgentInstrumentationSpecification {
   RedisCommands<String, ?> syncCommands
 
   def setupSpec() {
-    int port = PortUtils.randomOpenPort()
+    int port = PortUtils.findOpenPort()
     String dbAddr = PEER_HOST + ":" + port + "/" + DB_INDEX
     embeddedDbUri = "redis://" + dbAddr
 

instrumentation/lettuce/lettuce-5.0/javaagent/src/test/groovy/LettuceSyncClientTest.groovy

@@ -52,8 +52,8 @@ class LettuceSyncClientTest extends AgentInstrumentationSpecification {
   RedisCommands<String, ?> syncCommands
 
   def setupSpec() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
-    incorrectPort = PortUtils.randomOpenPort()
+    incorrectPort = PortUtils.findOpenPort()
     dbAddr = PEER_NAME + ":" + port + "/" + DB_INDEX
     dbAddrNonExistent = PEER_NAME + ":" + incorrectPort + "/" + DB_INDEX
     dbUriNonExistent = "redis://" + dbAddrNonExistent

instrumentation/lettuce/lettuce-5.1/testing/src/main/groovy/io/opentelemetry/instrumentation/lettuce/v5_1/AbstractLettuceAsyncClientTest.groovy

@@ -63,8 +63,8 @@ abstract class AbstractLettuceAsyncClientTest extends InstrumentationSpecificati
   RedisCommands<String, ?> syncCommands
 
   def setupSpec() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
-    incorrectPort = PortUtils.randomOpenPort()
+    incorrectPort = PortUtils.findOpenPort()
     dbAddr = HOST + ":" + port + "/" + DB_INDEX
     dbAddrNonExistent = HOST + ":" + incorrectPort + "/" + DB_INDEX
     dbUriNonExistent = "redis://" + dbAddrNonExistent

instrumentation/lettuce/lettuce-5.1/testing/src/main/groovy/io/opentelemetry/instrumentation/lettuce/v5_1/AbstractLettuceReactiveClientTest.groovy

@@ -40,7 +40,7 @@ abstract class AbstractLettuceReactiveClientTest extends InstrumentationSpecific
   RedisCommands<String, ?> syncCommands
 
   def setupSpec() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
     String dbAddr = HOST + ":" + port + "/" + DB_INDEX
     embeddedDbUri = "redis://" + dbAddr
 

instrumentation/lettuce/lettuce-5.1/testing/src/main/groovy/io/opentelemetry/instrumentation/lettuce/v5_1/AbstractLettuceSyncClientAuthTest.groovy

@@ -35,7 +35,7 @@ abstract class AbstractLettuceSyncClientAuthTest extends InstrumentationSpecific
   RedisClient redisClient
 
   def setupSpec() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
     dbAddr = HOST + ":" + port + "/" + DB_INDEX
     embeddedDbUri = "redis://" + dbAddr
     password = "password"

instrumentation/lettuce/lettuce-5.1/testing/src/main/groovy/io/opentelemetry/instrumentation/lettuce/v5_1/AbstractLettuceSyncClientTest.groovy

@@ -56,8 +56,8 @@ abstract class AbstractLettuceSyncClientTest extends InstrumentationSpecificatio
   RedisCommands<String, ?> syncCommands
 
   def setupSpec() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
-    incorrectPort = PortUtils.randomOpenPort()
+    incorrectPort = PortUtils.findOpenPort()
     dbAddr = HOST + ":" + port + "/" + DB_INDEX
     dbAddrNonExistent = HOST + ":" + incorrectPort + "/" + DB_INDEX
     dbUriNonExistent = "redis://" + dbAddrNonExistent

instrumentation/mongo/mongo-testing/src/main/groovy/MongoBaseTest.groovy

@@ -30,7 +30,7 @@ class MongoBaseTest extends AgentInstrumentationSpecification {
   private static final MongodStarter STARTER = MongodStarter.getDefaultInstance()
 
   @Shared
-  int port = PortUtils.randomOpenPort()
+  int port = PortUtils.findOpenPort()
   @Shared
   MongodExecutable mongodExe
   @Shared

instrumentation/rediscala-1.8/javaagent/src/test/groovy/RediscalaClientTest.groovy

@@ -22,7 +22,7 @@ import spock.lang.Shared
 class RediscalaClientTest extends AgentInstrumentationSpecification {
 
   @Shared
-  int port = PortUtils.randomOpenPort()
+  int port = PortUtils.findOpenPort()
 
   @Shared
   RedisServer redisServer = RedisServer.builder()

instrumentation/redisson-3.0/javaagent/src/test/groovy/RedissonAsyncClientTest.groovy

@@ -23,7 +23,7 @@ import spock.lang.Shared
 class RedissonAsyncClientTest extends AgentInstrumentationSpecification {
 
   @Shared
-  int port = PortUtils.randomOpenPort()
+  int port = PortUtils.findOpenPort()
 
   @Shared
   RedisServer redisServer = RedisServer.builder()

instrumentation/redisson-3.0/javaagent/src/test/groovy/RedissonClientTest.groovy

@@ -28,7 +28,7 @@ import spock.lang.Shared
 class RedissonClientTest extends AgentInstrumentationSpecification {
 
   @Shared
-  int port = PortUtils.randomOpenPort()
+  int port = PortUtils.findOpenPort()
 
   @Shared
   RedisServer redisServer = RedisServer.builder()

instrumentation/rmi/javaagent/src/test/groovy/RmiTest.groovy

@@ -18,7 +18,7 @@ import rmi.app.Server
 import rmi.app.ServerLegacy
 
 class RmiTest extends AgentInstrumentationSpecification {
-  def registryPort = PortUtils.randomOpenPort()
+  def registryPort = PortUtils.findOpenPort()
   def serverRegistry = LocateRegistry.createRegistry(registryPort)
   def clientRegistry = LocateRegistry.getRegistry("localhost", registryPort)
 

instrumentation/rocketmq-client-4.8/testing/src/main/java/base/IntegrationTestBase.java

@@ -5,6 +5,7 @@
 
 package base;
 
+import io.opentelemetry.instrumentation.test.utils.PortUtils;
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
@@ -12,7 +13,6 @@ import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.Random;
 import java.util.concurrent.atomic.AtomicInteger;
 import org.apache.rocketmq.broker.BrokerController;
 import org.apache.rocketmq.common.BrokerConfig;
@@ -37,13 +37,6 @@ public class IntegrationTestBase {
   protected static final List<NamesrvController> NAMESRV_CONTROLLERS = new ArrayList<>();
   protected static final int COMMIT_LOG_SIZE = 1024 * 1024 * 100;
   protected static final int INDEX_NUM = 1000;
-  private static final AtomicInteger port = new AtomicInteger(40000);
-
-  public static synchronized int nextPort() {
-    return port.addAndGet(random.nextInt(10) + 10);
-  }
-
-  protected static final Random random = new Random();
 
   private static String createTempDir() {
     String path = null;
@@ -77,7 +70,9 @@ public class IntegrationTestBase {
     namesrvConfig.setKvConfigPath(kvConfigPath.toString());
     namesrvConfig.setConfigStorePath(namesrvPath.toString());
 
-    nameServerNettyServerConfig.setListenPort(nextPort());
+    // find 3 consecutive open ports and use the last one of them
+    // rocketmq will also bind to given port - 2
+    nameServerNettyServerConfig.setListenPort(PortUtils.findOpenPorts(3) + 2);
     NamesrvController namesrvController =
         new NamesrvController(namesrvConfig, nameServerNettyServerConfig);
     try {
@@ -113,8 +108,8 @@ public class IntegrationTestBase {
       MessageStoreConfig storeConfig, BrokerConfig brokerConfig) {
     NettyServerConfig nettyServerConfig = new NettyServerConfig();
     NettyClientConfig nettyClientConfig = new NettyClientConfig();
-    nettyServerConfig.setListenPort(nextPort());
+    nettyServerConfig.setListenPort(PortUtils.findOpenPort());
-    storeConfig.setHaListenPort(nextPort());
+    storeConfig.setHaListenPort(PortUtils.findOpenPort());
     BrokerController brokerController =
         new BrokerController(brokerConfig, nettyServerConfig, nettyClientConfig, storeConfig);
     try {

instrumentation/spark-2.3/javaagent/src/test/groovy/SparkJavaBasedTest.groovy

@@ -22,7 +22,7 @@ class SparkJavaBasedTest extends AgentInstrumentationSpecification {
   OkHttpClient client = OkHttpUtils.client()
 
   def setupSpec() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
     TestSparkJavaApplication.initSpark(port)
   }
 

instrumentation/vertx-reactive-3.5/javaagent/src/test/groovy/VertxReactivePropagationTest.groovy

@@ -28,7 +28,7 @@ class VertxReactivePropagationTest extends AgentInstrumentationSpecification {
   Vertx server
 
   def setupSpec() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
     server = VertxReactiveWebServer.start(port)
   }
 

testing-common/src/main/groovy/io/opentelemetry/instrumentation/test/base/HttpServerTestTrait.groovy

@@ -40,7 +40,7 @@ trait HttpServerTestTrait<SERVER> implements RetryOnAddressAlreadyInUseTrait {
   }
 
   def setupSpecUnderRetry() {
-    port = PortUtils.randomOpenPort()
+    port = PortUtils.findOpenPort()
     address = buildAddress()
     server = startServer(port)
     println getClass().name + " http server started at: http://localhost:$port" + getContextPath()

testing-common/src/main/java/io/opentelemetry/instrumentation/test/utils/PortAllocator.java

@@ -0,0 +1,129 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.test.utils;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.net.ServerSocket;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Helper class for finding open ports that test servers can bind. Allocator splits allocation range
+ * to chunks and binds to the first port in chunk to claim it. If first port of chunk is already in
+ * use allocator assumes that some other process has already claimed that chunk and moves to next
+ * chunk. This should let us as run tests in parallel without them interfering with each other.
+ */
+class PortAllocator {
+
+  static final int CHUNK_SIZE = 100;
+  static final int RANGE_MIN = 11000;
+  // end of allocator port range, should be below ephemeral port range
+  static final int RANGE_MAX = 32768;
+
+  private final PortBinder portBinder;
+  private final List<Closeable> sockets = new ArrayList<>();
+  // next candidate port
+  private int next = RANGE_MIN;
+  private int nextChunkStart = RANGE_MIN;
+
+  PortAllocator() {
+    this(PortBinder.INSTANCE);
+  }
+
+  PortAllocator(PortBinder portBinder) {
+    this.portBinder = portBinder;
+
+    Runtime.getRuntime()
+        .addShutdownHook(
+            new Thread(
+                () -> {
+                  for (Closeable socket : sockets) {
+                    try {
+                      socket.close();
+                    } catch (IOException ignored) {
+                    }
+                  }
+                }));
+  }
+
+  /** Find open port. */
+  int getPort() {
+    return getPorts(1);
+  }
+
+  /** Find consecutive range of open ports, returning the first one in the range. */
+  synchronized int getPorts(int count) {
+    // as we bind to first port in each chunk the max amount of
+    // consecutive ports that we can find is CHUNK_SIZE - 1
+    if (count < 1 || count >= CHUNK_SIZE) {
+      throw new IllegalStateException("Invalid count " + count);
+    }
+    while (next + count - 1 <= RANGE_MAX) {
+      // if current chunk doesn't have enough ports move to next chunk
+      if (next + count - 1 >= nextChunkStart) {
+        reserveNextChunk();
+      }
+      // find requested amount of consecutive ports
+      while (next + count - 1 < nextChunkStart && next + count - 1 <= RANGE_MAX) {
+        // result is the lowest port in consecutive range
+        int result = next;
+        for (int i = 0; i < count; i++) {
+          int port = next;
+          next++;
+          if (!portBinder.canBind(port)) {
+            // someone has allocated a port in our port range, ignore it and try with
+            // the next port
+            break;
+          } else if (i == count - 1) {
+            return result;
+          }
+        }
+      }
+    }
+    // give up when port range is exhausted
+    throw new IllegalStateException("Failed to find suitable port");
+  }
+
+  private void reserveNextChunk() {
+    while (nextChunkStart < RANGE_MAX) {
+      // reserve a chunk, if binding to first port of chunk fails
+      // move to next chunk
+      Closeable serverSocket = portBinder.bind(nextChunkStart);
+      if (serverSocket != null) {
+        sockets.add(serverSocket);
+        next = nextChunkStart + 1;
+        nextChunkStart += CHUNK_SIZE;
+        return;
+      }
+      nextChunkStart += CHUNK_SIZE;
+    }
+    // give up when port range is exhausted
+    throw new IllegalStateException("Failed to reserve suitable port range");
+  }
+
+  static class PortBinder {
+    static PortBinder INSTANCE = new PortBinder();
+
+    Closeable bind(int port) {
+      try {
+        return new ServerSocket(port);
+      } catch (IOException exception) {
+        return null;
+      }
+    }
+
+    boolean canBind(int port) {
+      try {
+        ServerSocket socket = new ServerSocket(port);
+        socket.close();
+        return true;
+      } catch (IOException exception) {
+        return false;
+      }
+    }
+  }
+}

testing-common/src/main/java/io/opentelemetry/instrumentation/test/utils/PortUtils.java

@@ -6,7 +6,6 @@
 package io.opentelemetry.instrumentation.test.utils;
 
 import java.io.IOException;
-import java.net.ServerSocket;
 import java.net.Socket;
 import java.util.concurrent.TimeUnit;
 
@@ -14,18 +13,16 @@ public class PortUtils {
 
   public static int UNUSABLE_PORT = 61;
 
-  /** Open up a random, reusable port. */
+  private static final PortAllocator portAllocator = new PortAllocator();
-  public static int randomOpenPort() {
+
-    ServerSocket socket;
+  /** Find consecutive open ports, returning the first one in the range. */
-    try {
+  public static int findOpenPorts(int count) {
-      socket = new ServerSocket(0);
+    return portAllocator.getPorts(count);
-      socket.setReuseAddress(true);
+  }
-      socket.close();
+
-      return socket.getLocalPort();
+  /** Find open port. */
-    } catch (IOException ioe) {
+  public static int findOpenPort() {
-      ioe.printStackTrace();
+    return portAllocator.getPort();
-      return -1;
-    }
   }
 
   private static boolean isPortOpen(int port) {

testing-common/src/test/java/io/opentelemetry/instrumentation/test/utils/PortAllocatorTest.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.test.utils;
+
+import java.io.Closeable;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class PortAllocatorTest {
+
+  @Test
+  public void testSimple() {
+    PortAllocator portAllocator = getPortAllocator((port) -> true);
+    int next = PortAllocator.RANGE_MIN + 1;
+    for (int i = 0; i < 1000; i++) {
+      Assertions.assertEquals(next, portAllocator.getPort());
+      next++;
+      if (next % PortAllocator.CHUNK_SIZE == 0) {
+        next++;
+      }
+    }
+    Assertions.assertEquals(next, portAllocator.getPorts(10));
+    Assertions.assertEquals(12101, portAllocator.getPorts(PortAllocator.CHUNK_SIZE - 1));
+    try {
+      Assertions.assertEquals(next, portAllocator.getPorts(PortAllocator.CHUNK_SIZE + 1));
+      Assertions.fail("should not be able to allocate more than PORT_RANGE_STEP consecutive ports");
+    } catch (IllegalStateException ignored) {
+    }
+  }
+
+  @Test
+  public void testEven() {
+    PortAllocator portAllocator = getPortAllocator((port) -> port % 2 == 0);
+    int next = PortAllocator.RANGE_MIN + 2;
+    for (int i = 0; i < 1000; i++) {
+      Assertions.assertEquals(next, portAllocator.getPort());
+      next += 2;
+      if (next % PortAllocator.CHUNK_SIZE == 0) {
+        next += 2;
+      }
+    }
+    try {
+      Assertions.assertEquals(next, portAllocator.getPorts(2));
+      Assertions.fail("should not be able to allocate consecutive ports");
+    } catch (IllegalStateException ignored) {
+    }
+  }
+
+  private static PortAllocator getPortAllocator(PortTest portTest) {
+    return new PortAllocator(new TestPortBinder(portTest));
+  }
+
+  private interface PortTest {
+    boolean test(int port);
+  }
+
+  private static class TestPortBinder extends PortAllocator.PortBinder {
+    private final PortTest portTest;
+
+    TestPortBinder(PortTest portTest) {
+      this.portTest = portTest;
+    }
+
+    @Override
+    Closeable bind(int port) {
+      if (canBind(port)) {
+        return () -> {};
+      }
+      return null;
+    }
+
+    @Override
+    boolean canBind(int port) {
+      return portTest.test(port);
+    }
+  }
+}