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The following commit(s) were added to refs/heads/camel-4.14.x by this push:
new da488668350b CAMEL-24244: Fix DefaultStreamCachingStrategy.updateSpool
releasing the lock
da488668350b is described below
commit da488668350bcdc8e511cf094bc98937a3a493c8
Author: Claus Ibsen <[email protected]>
AuthorDate: Sat Jul 25 09:43:58 2026 +0200
CAMEL-24244: Fix DefaultStreamCachingStrategy.updateSpool releasing the lock
Backport of #25085 — fix copy-paste bug where updateSpool() called
lock.lock() instead of lock.unlock() in its finally block, causing
unbounded hold count growth and thread starvation.
Co-Authored-By: Claude Opus 4.6 <[email protected]>
---
.../impl/engine/DefaultStreamCachingStrategy.java | 2 +-
.../StreamCachingStrategySpoolStatisticsTest.java | 171 +++++++++++++++++++++
2 files changed, 172 insertions(+), 1 deletion(-)
diff --git
a/core/camel-base-engine/src/main/java/org/apache/camel/impl/engine/DefaultStreamCachingStrategy.java
b/core/camel-base-engine/src/main/java/org/apache/camel/impl/engine/DefaultStreamCachingStrategy.java
index 4d08955e1aaa..800132895e85 100644
---
a/core/camel-base-engine/src/main/java/org/apache/camel/impl/engine/DefaultStreamCachingStrategy.java
+++
b/core/camel-base-engine/src/main/java/org/apache/camel/impl/engine/DefaultStreamCachingStrategy.java
@@ -583,7 +583,7 @@ public class DefaultStreamCachingStrategy extends
ServiceSupport implements Came
try {
spoolAverageSize.set(spoolSize.addAndGet(size) /
spoolCounter.incrementAndGet());
} finally {
- lock.lock();
+ lock.unlock();
}
}
diff --git
a/core/camel-core/src/test/java/org/apache/camel/impl/engine/StreamCachingStrategySpoolStatisticsTest.java
b/core/camel-core/src/test/java/org/apache/camel/impl/engine/StreamCachingStrategySpoolStatisticsTest.java
new file mode 100644
index 000000000000..82b7f3eab2c9
--- /dev/null
+++
b/core/camel-core/src/test/java/org/apache/camel/impl/engine/StreamCachingStrategySpoolStatisticsTest.java
@@ -0,0 +1,171 @@
+/*
+ * 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.impl.engine;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.apache.camel.ContextTestSupport;
+import org.apache.camel.Exchange;
+import org.apache.camel.StreamCache;
+import org.apache.camel.support.DefaultExchange;
+import org.apache.camel.support.TypeConverterSupport;
+import org.apache.camel.support.service.ServiceHelper;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Reproduces CAMEL-24244: {@code UtilizationStatistics.updateSpool()}
re-acquired the lock in its {@code finally} block
+ * instead of releasing it, so the lock was never released and every later
caller blocked forever.
+ * <p>
+ * A single thread cannot detect this, because the lock is a {@link
java.util.concurrent.locks.ReentrantLock} that its
+ * owner is free to re-acquire. The bug only shows up once a
<em>different</em> thread updates the spool statistics, so
+ * this test drives the spool accounting from two threads.
+ * <p>
+ * Two deliberate design choices keep a regression from wedging the build,
because
+ * {@link java.util.concurrent.locks.ReentrantLock#lock()} is uninterruptible
and cannot be recovered once leaked:
+ * <ul>
+ * <li>a standalone {@link DefaultStreamCachingStrategy} is used instead of
the context-managed one, since
+ * {@code doStop()} calls {@code statistics.reset()} and would otherwise
deadlock {@code CamelContext} shutdown;</li>
+ * <li>the worker threads are daemons, so a permanently blocked thread cannot
keep the JVM alive.</li>
+ * </ul>
+ * A stub converter supplies a cache that reports itself as spooled, which
exercises the spool accounting directly
+ * without depending on real disk spooling.
+ */
+class StreamCachingStrategySpoolStatisticsTest extends ContextTestSupport {
+
+ private static final int THREADS = 2;
+ private static final long SPOOLED_LENGTH = 1024L;
+
+ @Override
+ public boolean isUseRouteBuilder() {
+ return false;
+ }
+
+ @Test
+ @Timeout(60)
+ void shouldUpdateSpoolStatisticsFromConcurrentThreads() throws Exception {
+ // a body type whose only converter yields a cache that reports itself
as spooled
+ context.getTypeConverterRegistry().addTypeConverter(StreamCache.class,
SpooledBody.class,
+ new TypeConverterSupport() {
+ @Override
+ public <T> T convertTo(Class<T> type, Exchange exchange,
Object value) {
+ return type.cast(new SpooledCache());
+ }
+ });
+
+ DefaultStreamCachingStrategy strategy = new
DefaultStreamCachingStrategy();
+ strategy.setCamelContext(context);
+ strategy.setEnabled(true);
+ strategy.getStatistics().setStatisticsEnabled(true);
+ // picks up the converter above, so cache() routes through the spool
accounting
+ ServiceHelper.startService(strategy);
+
+ ExecutorService executor = Executors.newFixedThreadPool(THREADS, r -> {
+ Thread t = new Thread(r, "spool-stats-test");
+ t.setDaemon(true);
+ return t;
+ });
+ CountDownLatch ready = new CountDownLatch(THREADS);
+ CountDownLatch finished = new CountDownLatch(THREADS);
+ AtomicInteger spooled = new AtomicInteger();
+ AtomicReference<Throwable> error = new AtomicReference<>();
+ try {
+ for (int i = 0; i < THREADS; i++) {
+ executor.execute(() -> {
+ try {
+ ready.countDown();
+ // release both threads together so they contend on
the statistics lock
+ ready.await(10, TimeUnit.SECONDS);
+ Exchange exchange = new DefaultExchange(context);
+ exchange.getIn().setBody(new SpooledBody());
+ StreamCache cache = strategy.cache(exchange);
+ if (cache != null && !cache.inMemory()) {
+ spooled.incrementAndGet();
+ } else {
+ error.compareAndSet(null,
+ new IllegalStateException("expected a
spooled cache but got: " + cache));
+ }
+ } catch (Throwable t) {
+ error.compareAndSet(null, t);
+ } finally {
+ finished.countDown();
+ }
+ });
+ }
+
+ // before CAMEL-24244 the second thread blocked forever in
updateSpool, so this never reached zero
+ assertThat(finished.await(15, TimeUnit.SECONDS))
+ .as("both threads must finish; one blocked on the leaked
spool statistics lock")
+ .isTrue();
+ } finally {
+ executor.shutdownNow();
+ }
+
+ assertThat(spooled)
+ .as("both threads should have gone through the spool
accounting; first error=" + error.get())
+ .hasValue(THREADS);
+
assertThat(strategy.getStatistics().getCacheSpoolCounter()).isEqualTo(THREADS);
+
assertThat(strategy.getStatistics().getCacheSpoolSize()).isEqualTo(THREADS *
SPOOLED_LENGTH);
+ }
+
+ /** Marker body type so the stub converter below is selected. */
+ private static final class SpooledBody {
+ }
+
+ /** Minimal {@link StreamCache} that reports itself as spooled to disk. */
+ private static final class SpooledCache implements StreamCache {
+
+ @Override
+ public void reset() {
+ // noop
+ }
+
+ @Override
+ public void writeTo(OutputStream os) throws IOException {
+ // noop
+ }
+
+ @Override
+ public StreamCache copy(Exchange exchange) {
+ return new SpooledCache();
+ }
+
+ @Override
+ public boolean inMemory() {
+ return false;
+ }
+
+ @Override
+ public long length() {
+ return SPOOLED_LENGTH;
+ }
+
+ @Override
+ public long position() {
+ return -1;
+ }
+ }
+}
