[Java] Fix Java test issues (#7000)

java/test/src/main/java/org/ray/api/test/FailureTest.java

@@ -14,12 +14,27 @@ import org.ray.api.exception.RayTaskException;
 import org.ray.api.exception.RayWorkerException;
 import org.ray.api.function.RayFunc0;
 import org.testng.Assert;
+import org.testng.annotations.AfterClass;
+import org.testng.annotations.BeforeClass;
 import org.testng.annotations.Test;
 
 public class FailureTest extends BaseTest {
 
   private static final String EXCEPTION_MESSAGE = "Oops";
 
+  @BeforeClass
+  public void setUp() {
+    // This is needed by `testGetThrowsQuicklyWhenFoundException`.
+    // Set one worker per process. Otherwise, if `badFunc2` and `slowFunc` run in the same
+    // process, `sleep` will delay `System.exit`.
+    System.setProperty("ray.raylet.config.num_workers_per_process_java", "1");
+  }
+
+  @AfterClass
+  public void tearDown() {
+    System.clearProperty("ray.raylet.config.num_workers_per_process_java");
+  }
+
   public static int badFunc() {
     throw new RuntimeException(EXCEPTION_MESSAGE);
   }

java/test/src/main/java/org/ray/api/test/RayConfigTest.java

@@ -7,7 +7,7 @@ import org.testng.annotations.Test;
 
 public class RayConfigTest {
 
-  public final static int NUM_RETRIES = 5;
+  public static final int NUM_RETRIES = 5;
 
   @Test
   public void testCreateRayConfig() {