diff --git a/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/it/runner/registry/TestBench.java b/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/it/runner/registry/TestBench.java
index 4d9340762093..964c0c5cb020 100644
--- a/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/it/runner/registry/TestBench.java
+++ b/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/it/runner/registry/TestBench.java
@@ -262,7 +262,7 @@ public void start() {
               dockerImage,
               "gunicorn",
               "--bind=0.0.0.0:9000",
-              "--worker-class=sync",
+              "--worker-class=gthread",
               "--threads=10",
               "--access-logfile=-",
               "--keep-alive=0",
@@ -401,6 +401,16 @@ private void dumpServerLog(String prefix, File out) throws IOException {
     }
   }
 
+  private static int findFreePort() {
+    try (java.net.ServerSocket socket = new java.net.ServerSocket()) {
+      socket.setReuseAddress(true);
+      socket.bind(new java.net.InetSocketAddress("127.0.0.1", 0));
+      return socket.getLocalPort();
+    } catch (java.io.IOException e) {
+      throw new RuntimeException("Failed to find a free port", e);
+    }
+  }
+
   static Builder newBuilder() {
     return new Builder();
   }
@@ -442,8 +452,8 @@ public String toString() {
   }
 
   static final class Builder {
-    private static final String DEFAULT_BASE_URI = "http://localhost:9000";
-    private static final String DEFAULT_GRPC_BASE_URI = "http://localhost:9005";
+    private static final String DEFAULT_BASE_URI = "http://localhost";
+    private static final String DEFAULT_GRPC_BASE_URI = "http://localhost";
     private static final String DEFAULT_IMAGE_NAME;
     private static final String DEFAULT_IMAGE_TAG;
 
@@ -497,11 +507,11 @@ static final class Builder {
     private Builder() {
       this(
           false,
-          DEFAULT_BASE_URI,
-          DEFAULT_GRPC_BASE_URI,
+          DEFAULT_BASE_URI + ":" + findFreePort(),
+          DEFAULT_GRPC_BASE_URI + ":" + findFreePort(),
           DEFAULT_IMAGE_NAME,
           DEFAULT_IMAGE_TAG,
-          DEFAULT_CONTAINER_NAME);
+          DEFAULT_CONTAINER_NAME + "_" + java.util.UUID.randomUUID().toString().substring(0, 8));
     }
 
     private Builder(