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new e4315e71a3e1 CAMEL-26634: camel-core - Resequence EIP: batch mode can
run two senders after a route restart (#29370)
e4315e71a3e1 is described below
commit e4315e71a3e12ac99c4738cfc89f542400851758
Author: allthingssecurity <[email protected]>
AuthorDate: Sat Nov 7 13:31:26 2026 +0530
CAMEL-26634: camel-core - Resequence EIP: batch mode can run two senders
after a route restart (#29370)
Co-Authored-By: Claude Opus 5.5 <[email protected]>
---
.../org/apache/camel/processor/Resequencer.java | 46 ++++++-
.../processor/BatchResequencerRestartTest.java | 146 +++++++++++++++++++++
2 files changed, 189 insertions(+), 3 deletions(-)
diff --git
a/core/camel-core-processor/src/main/java/org/apache/camel/processor/Resequencer.java
b/core/camel-core-processor/src/main/java/org/apache/camel/processor/Resequencer.java
index b84d3b6fb9f4..89232bbf0972 100644
---
a/core/camel-core-processor/src/main/java/org/apache/camel/processor/Resequencer.java
+++
b/core/camel-core-processor/src/main/java/org/apache/camel/processor/Resequencer.java
@@ -67,6 +67,7 @@ public class Resequencer extends BaseProcessorSupport
public static final int DEFAULT_BATCH_SIZE = 100;
private static final Logger LOG =
LoggerFactory.getLogger(Resequencer.class);
+ private static final long PREVIOUS_SENDER_WARN_TIMEOUT = 10000;
private String id;
private String routeId;
@@ -87,6 +88,8 @@ public class Resequencer extends BaseProcessorSupport
private final Collection<Exchange> collection;
private ExceptionHandler exceptionHandler;
private BatchSender sender;
+ // the sender of the last start, which may still be delivering an exchange
when the route is started again
+ private BatchSender stoppedSender;
public Resequencer(CamelContext camelContext, Processor processor,
Expression expression) {
this(camelContext, processor, createSet(expression, false, false),
expression);
@@ -350,13 +353,15 @@ public class Resequencer extends BaseProcessorSupport
@Override
protected void doStart() throws Exception {
ServiceHelper.startService(processor);
- sender = new BatchSender();
+ sender = new BatchSender(stoppedSender);
+ stoppedSender = null;
sender.start();
}
@Override
protected void doStop() throws Exception {
if (sender != null) {
+ stoppedSender = sender;
try {
sender.cancel();
} catch (Exception e) {
@@ -427,14 +432,25 @@ public class Resequencer extends BaseProcessorSupport
private final AtomicBoolean exchangeEnqueued = new AtomicBoolean();
private final Queue<String> completionPredicateMatched = new
ConcurrentLinkedQueue<>();
private final Condition exchangeEnqueuedCondition =
queueLock.newCondition();
+ private volatile boolean cancelled;
+ private BatchSender previous;
- BatchSender() {
+ BatchSender(BatchSender previous) {
super(camelContext.getExecutorServiceManager().resolveThreadName("Batch
Sender"));
this.queue = new LinkedList<>();
+ this.previous = previous;
}
@Override
public void run() {
+ // the previous sender may still be sending from the shared
collection, so wait for it to end
+ if (previous != null) {
+ awaitPrevious();
+ }
+ if (cancelled) {
+ return;
+ }
+
// Wait until one of either:
// * an exchange being queued;
// * the batch timeout expiring; or
@@ -512,7 +528,7 @@ public class Resequencer extends BaseProcessorSupport
break;
}
- } while (isRunAllowed());
+ } while (isRunAllowed() && !cancelled);
} finally {
queueLock.unlock();
@@ -543,7 +559,31 @@ public class Resequencer extends BaseProcessorSupport
}
}
+ private void awaitPrevious() {
+ boolean interrupted = false;
+ boolean logged = false;
+ while (previous.isAlive()) {
+ try {
+ previous.join(PREVIOUS_SENDER_WARN_TIMEOUT);
+ if (!logged && previous.isAlive()) {
+ logged = true;
+ LOG.warn("Route: {} waiting for previous batch sender:
{} to complete sending its batch", routeId,
+ previous.getName());
+ }
+ } catch (InterruptedException e) {
+ // keep waiting, as a sender started later waits for this
one
+ interrupted = true;
+ }
+ }
+ previous = null;
+ if (interrupted) {
+ Thread.currentThread().interrupt();
+ }
+ }
+
public void cancel() {
+ // also end on a flag, as the processing may clear the interrupt
status
+ cancelled = true;
interrupt();
}
diff --git
a/core/camel-core/src/test/java/org/apache/camel/processor/BatchResequencerRestartTest.java
b/core/camel-core/src/test/java/org/apache/camel/processor/BatchResequencerRestartTest.java
new file mode 100644
index 000000000000..735a2652260d
--- /dev/null
+++
b/core/camel-core/src/test/java/org/apache/camel/processor/BatchResequencerRestartTest.java
@@ -0,0 +1,146 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.camel.processor;
+
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.camel.ContextTestSupport;
+import org.apache.camel.Exchange;
+import org.apache.camel.builder.RouteBuilder;
+import org.apache.camel.component.mock.MockEndpoint;
+import org.junit.jupiter.api.Test;
+
+import static org.awaitility.Awaitility.await;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * The batch resequencer must deliver one exchange at a time, in order, when
its route is stopped and started while the
+ * sender thread of the previous start is still delivering an exchange, and
that sender must end.
+ */
+public class BatchResequencerRestartTest extends ContextTestSupport {
+
+ private final List<String> events = new CopyOnWriteArrayList<>();
+ private final CountDownLatch firstInside = new CountDownLatch(1);
+ private final CountDownLatch otherStarted = new CountDownLatch(1);
+ private volatile boolean restoreInterrupt = true;
+
+ @Test
+ public void testRestartWhileDeliveringKeepsOrder() throws Exception {
+ MockEndpoint mock = getMockEndpoint("mock:result");
+ mock.expectedBodiesReceived("1", "2", "3", "4");
+
+ restartWhileDeliveringFirst();
+
+ mock.assertIsSatisfied();
+ assertEquals(List.of("start-1", "end-1", "start-2", "end-2",
"start-3", "end-3", "start-4", "end-4"), events);
+ }
+
+ @Test
+ public void testRestartTwiceWhileDeliveringKeepsOrder() throws Exception {
+ MockEndpoint mock = getMockEndpoint("mock:result");
+ mock.expectedBodiesReceived("1", "2", "3", "4");
+
+ restartWhileDeliveringFirst(2);
+
+ mock.assertIsSatisfied();
+ assertEquals(List.of("start-1", "end-1", "start-2", "end-2",
"start-3", "end-3", "start-4", "end-4"), events);
+ await().atMost(10, TimeUnit.SECONDS).until(() -> senderThreads() == 1);
+ }
+
+ @Test
+ public void testSenderThreadEndsWhenRestartedWhileDelivering() throws
Exception {
+ // the processing of the first exchange does not keep the interrupt
status of the thread, as some libraries do
+ restoreInterrupt = false;
+ MockEndpoint mock = getMockEndpoint("mock:result");
+ mock.expectedBodiesReceivedInAnyOrder("1", "2", "3", "4");
+
+ restartWhileDeliveringFirst();
+
+ mock.assertIsSatisfied();
+ // only the sender of the last start is left
+ await().atMost(10, TimeUnit.SECONDS).until(() -> senderThreads() == 1);
+ }
+
+ private void restartWhileDeliveringFirst() throws Exception {
+ restartWhileDeliveringFirst(1);
+ }
+
+ private void restartWhileDeliveringFirst(int restarts) throws Exception {
+ // a batch of 2: the sender delivers 1, and 2 waits in the batch
+ template.sendBodyAndHeader("direct:start", "1", "seq", 1);
+ template.sendBodyAndHeader("direct:start", "2", "seq", 2);
+ assertTrue(firstInside.await(10, TimeUnit.SECONDS));
+
+ // the route is stopped and started while 1 is being delivered (the
stop does not wait for it)
+ for (int i = 0; i < restarts; i++) {
+ context.getRouteController().stopRoute("batch");
+ context.getRouteController().startRoute("batch");
+ }
+
+ template.sendBodyAndHeader("direct:start", "3", "seq", 3);
+ template.sendBodyAndHeader("direct:start", "4", "seq", 4);
+ }
+
+ private void deliver(Exchange exchange) {
+ String body = exchange.getMessage().getBody(String.class);
+ events.add("start-" + body);
+ if ("1".equals(body)) {
+ firstInside.countDown();
+ // the window in which no other exchange may start while 1 is
processed
+ boolean interrupted = false;
+ long deadline = System.nanoTime() + TimeUnit.SECONDS.toNanos(1);
+ while (otherStarted.getCount() > 0 && System.nanoTime() <
deadline) {
+ try {
+ otherStarted.await(deadline - System.nanoTime(),
TimeUnit.NANOSECONDS);
+ } catch (InterruptedException e) {
+ interrupted = true;
+ }
+ }
+ if (interrupted && restoreInterrupt) {
+ Thread.currentThread().interrupt();
+ }
+ } else {
+ otherStarted.countDown();
+ }
+ events.add("end-" + body);
+ }
+
+ private long senderThreads() {
+ return Thread.getAllStackTraces().keySet().stream()
+ .filter(Thread::isAlive)
+ .filter(t -> t.getName().contains("(" + context.getName() +
")"))
+ .filter(t -> t.getName().endsWith("Batch Sender"))
+ .count();
+ }
+
+ @Override
+ protected RouteBuilder createRouteBuilder() {
+ return new RouteBuilder() {
+ @Override
+ public void configure() {
+ from("direct:start").routeId("batch")
+
.resequence(header("seq")).batch().size(2).timeout(60000)
+ .process(BatchResequencerRestartTest.this::deliver)
+ .to("mock:result");
+ }
+ };
+ }
+}
