[Java] Enable GCS server when running java unit tests (#7041)

* enable gcs service when run java testcase

* fix ci bug

* fix windows compile bug

* fix ci bug

* restart ci job

* enable java testcase

* restart ci job

* restart ci job

* add debug log

* add debug log

* restart ci job

* add debug log

* restart ci

* add debug log

* fix java testcase bug

* restart ci job

* restart ci job

* restart ci job

* restart ci job

* restart ci job

* restart ci job

* restart ci job

* restart ci job

python/ray/services.py

@@ -55,6 +55,8 @@ RAYLET_MONITOR_EXECUTABLE = os.path.join(
     "core/src/ray/raylet/raylet_monitor")
 RAYLET_EXECUTABLE = os.path.join(
     os.path.abspath(os.path.dirname(__file__)), "core/src/ray/raylet/raylet")
+GCS_SERVER_EXECUTABLE = os.path.join(
+    os.path.abspath(os.path.dirname(__file__)), "core/src/ray/gcs/gcs_server")
 
 DEFAULT_JAVA_WORKER_OPTIONS = "-classpath {}".format(
     os.path.join(
@@ -1083,6 +1085,44 @@ def start_dashboard(require_webui,
         return None, None
 
 
+def start_gcs_server(redis_address,
+                     stdout_file=None,
+                     stderr_file=None,
+                     redis_password=None,
+                     config=None):
+    """Start a gcs server.
+    Args:
+        redis_address (str): The address that the Redis server is listening on.
+        stdout_file: A file handle opened for writing to redirect stdout to. If
+            no redirection should happen, then this should be None.
+        stderr_file: A file handle opened for writing to redirect stderr to. If
+            no redirection should happen, then this should be None.
+        redis_password (str): The password of the redis server.
+        config (dict|None): Optional configuration that will
+            override defaults in RayConfig.
+    Returns:
+        ProcessInfo for the process that was started.
+    """
+    gcs_ip_address, gcs_port = redis_address.split(":")
+    redis_password = redis_password or ""
+    config = config or {}
+    config_str = ",".join(["{},{}".format(*kv) for kv in config.items()])
+    command = [
+        GCS_SERVER_EXECUTABLE,
+        "--redis_address={}".format(gcs_ip_address),
+        "--redis_port={}".format(gcs_port),
+        "--config_list={}".format(config_str),
+    ]
+    if redis_password:
+        command += ["--redis_password={}".format(redis_password)]
+    process_info = start_ray_process(
+        command,
+        ray_constants.PROCESS_TYPE_GCS_SERVER,
+        stdout_file=stdout_file,
+        stderr_file=stderr_file)
+    return process_info
+
+
 def start_raylet(redis_address,
                  node_ip_address,
                  node_manager_port,