apache/seatunnel · info · IllegalStateException

Utility class

Error message

Utility class

What it means

IllegalStateException thrown from the private constructor of RequestFutureCache, a static utility class holding pending request futures. This is a defensive guard to prevent instantiation of the class, which only exposes static methods. It only fires if a developer tries `new RequestFutureCache()` via reflection, serialization, or inside the same class.

Solutions

1. Remove any code that instantiates RequestFutureCache and call its static methods instead
2. If instantiation is intentional, refactor the needed functionality into a non-utility class
3. In tests, suppress instantiation attempts rather than calling the constructor

Example fix

// before
RequestFutureCache cache = new RequestFutureCache();
// after
RequestFuture future = RequestFutureCache.get(requestId); // use static access

// never instantiate; just use statics
assert Modifier.isPrivate(RequestFutureCache.class.getDeclaredConstructor().getModifiers());

When it happens

Trigger: Any attempt to instantiate RequestFutureCache: direct constructor call (impossible from outside due to private access), reflection with setAccessible(true), or accidental deserialization of the class.

Common situations: Refactor or test code trying to instantiate utility classes; reflection-based frameworks (e.g. some mocking or serialization tools) probing constructors.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• ACKNOWLEDGE_FAILED
• Already an MDCCallable
• Already an MDCComparator
• Already an MDCConsumer
• Already an MDCExecutor

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/6222f3ae32204901. Report an issue: GitHub.

Appendix: source

Thrown at seatunnel-engine/seatunnel-engine-storage/imap-storage-plugins/imap-storage-file/src/main/java/org/apache/seatunnel/engine/imap/storage/file/future/RequestFutureCache.java:29

 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 */

package org.apache.seatunnel.engine.imap.storage.file.future;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;

public class RequestFutureCache {

    private RequestFutureCache() {
        throw new IllegalStateException("Utility class");
    }

    private static AtomicLong REQUEST_ID_GEN = new AtomicLong(0);

    private static ConcurrentHashMap<Long, RequestFuture> REQUEST_MAP = new ConcurrentHashMap<>();

    public static void put(long requestId, RequestFuture requestFuture) {
        REQUEST_MAP.put(requestId, requestFuture);
    }

    public static RequestFuture get(Long requestId) {
        return REQUEST_MAP.get(requestId);
    }

    public static void remove(Long requestId) {
        REQUEST_MAP.remove(requestId);
    }

View on GitHub (pinned to cf67b549a7)