[improve][broker] Update netty allocator default chunk size from 4MB to 8MB

bin/function-localrunner

@@ -77,7 +77,7 @@ if [[ -z "$PULSAR_GC_LOG" ]]; then
 fi
 
 # Extra options to be passed to the jvm
-PULSAR_EXTRA_OPTS=${PULSAR_EXTRA_OPTS:-" -Dpulsar.allocator.exit_on_oom=true -Dio.netty.recycler.maxCapacityPerThread=4096"}
+PULSAR_EXTRA_OPTS=${PULSAR_EXTRA_OPTS:-" -Dpulsar.allocator.exit_on_oom=true -Dio.netty.recycler.maxCapacityPerThread=4096 -Dio.netty.allocator.maxOrder=10"}
 
 if [ -z "$PULSAR_LOG_CONF" ]; then
     PULSAR_LOG_CONF=$DEFAULT_LOG_CONF

conf/pulsar_env.sh

@@ -90,7 +90,7 @@ if [[ -z "$PULSAR_GC_LOG" ]]; then
 fi
 
 # Extra options to be passed to the jvm
-PULSAR_EXTRA_OPTS="${PULSAR_EXTRA_OPTS:-" -Dpulsar.allocator.exit_on_oom=true -Dio.netty.recycler.maxCapacityPerThread=4096"}"
+PULSAR_EXTRA_OPTS="${PULSAR_EXTRA_OPTS:-" -Dpulsar.allocator.exit_on_oom=true -Dio.netty.recycler.maxCapacityPerThread=4096 -Dio.netty.allocator.maxOrder=10"}"
 
 # Add extra paths to the bookkeeper classpath
 # PULSAR_EXTRA_CLASSPATH=

deployment/terraform-ansible/templates/pulsar_env.sh

@@ -48,7 +48,7 @@ PULSAR_MEM=" -Xms{{ max_heap_memory }} -Xmx{{ max_heap_memory }} -XX:MaxDirectMe
 PULSAR_GC=" -XX:+UseZGC -XX:+PerfDisableSharedMem -XX:+AlwaysPreTouch"
 
 # Extra options to be passed to the jvm
-PULSAR_EXTRA_OPTS="-Dio.netty.leakDetection.level=disabled -Dio.netty.recycler.maxCapacityPerThread=4096 ${PULSAR_EXTRA_OPTS}"
+PULSAR_EXTRA_OPTS="-Dio.netty.leakDetection.level=disabled -Dio.netty.recycler.maxCapacityPerThread=4096 -Dio.netty.allocator.maxOrder=10 ${PULSAR_EXTRA_OPTS}"
 
 # Add extra paths to the bookkeeper classpath
 # PULSAR_EXTRA_CLASSPATH=

pulsar-common/src/test/java/org/apache/pulsar/common/allocator/PulsarByteBufAllocatorDefaultTest.java

@@ -23,6 +23,8 @@
 import static org.testng.Assert.assertNotNull;
 import static org.testng.Assert.assertTrue;
 import io.netty.buffer.ByteBufAllocator;
+import io.netty.buffer.PooledByteBufAllocator;
+import io.netty.buffer.PooledByteBufAllocatorMetric;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
 import org.apache.bookkeeper.common.allocator.OutOfMemoryPolicy;
@@ -54,4 +56,38 @@ public void testDefaultConfig() {
         }
     }
 
+    /**
+     * Verify that a {@link PooledByteBufAllocator} created with {@code maxOrder=10} produces the expected chunk size,
+     * which is consistent with the {@code -Dio.netty.allocator.maxOrder=10} setting in {@code conf/pulsar_env.sh}.
+     *
+     * <p>Netty computes chunk size as: {@code pageSize << maxOrder = 8192 << 10 = 8,388,608 bytes (8 MiB)}.
+     * This test constructs the allocator directly with {@code maxOrder=10} so no JVM argument is required.
+     */
+    @Test
+    public void testDefaultChunkSizeMatchesMaxOrder10() {
+        // Expected chunk size: pageSize (8192 bytes) << maxOrder (10) = 8 MiB
+        final int maxOrder = 10;
+        final int expectedChunkSize = 8192 << maxOrder;
+
+        // Create a PooledByteBufAllocator with maxOrder=10, same as -Dio.netty.allocator.maxOrder=10
+        PooledByteBufAllocator allocator = new PooledByteBufAllocator(
+                true,           // preferDirect
+                0,                        // nHeapArena
+                1,                        // nDirectArena
+                8192,                     // pageSize (default)
+                maxOrder,                 // maxOrder=10
+                64,                       // smallPageSize (default)
+                256,                      // normalPageSize (default)
+                false,
+                0
+        );
+
+        PooledByteBufAllocatorMetric metric = allocator.metric();
+        // Verify that the chunk size derived from maxOrder=10 equals 8 MiB
+        assertEquals(metric.chunkSize(), expectedChunkSize,
+                "Chunk size should be 8 MiB (pageSize << maxOrder = 8192 << 10) "
+                        + "as configured by -Dio.netty.allocator.maxOrder=10 in pulsar_env.sh");
+
+    }
+
 }

tests/integration/src/test/java/org/apache/pulsar/tests/integration/containers/PulsarContainer.java

@@ -301,7 +301,7 @@ protected void passNettyLeakDetectionSystemProperties() {
 
     protected void initializePulsarExtraOpts() {
         appendToEnv("PULSAR_EXTRA_OPTS",
-                "-Dpulsar.allocator.exit_on_oom=true -Dio.netty.recycler.maxCapacityPerThread=4096");
+                "-Dpulsar.allocator.exit_on_oom=true -Dio.netty.recycler.maxCapacityPerThread=4096 -Dio.netty.allocator.maxOrder=10");
     }
 
     protected boolean isCodeCoverageEnabled() {