[improve][broker] Change bookkeeperClientSeparatedIoThreadsEnabled to True by default

conf/broker.conf

@@ -1112,8 +1112,8 @@ bookkeeperClientNumWorkerThreads=
 bookkeeperClientNumIoThreads=
 
 # Use separated IO threads for BookKeeper client
-# Default is false, which will use Pulsar IO threads
-bookkeeperClientSeparatedIoThreadsEnabled=false
+# Default is true, which will use dedicated BookKeeper IO threads
+bookkeeperClientSeparatedIoThreadsEnabled=true
 
 # Speculative reads are initiated if a read request doesn't complete within a certain time
 # Using a value of 0, is disabling the speculative reads

conf/standalone.conf

@@ -682,8 +682,8 @@ bookkeeperClientNumWorkerThreads=
 bookkeeperClientNumIoThreads=
 
 # Use separated IO threads for BookKeeper client
-# Default is false, which will use Pulsar IO threads
-bookkeeperClientSeparatedIoThreadsEnabled=false
+# Default is true, which will use dedicated BookKeeper IO threads
+bookkeeperClientSeparatedIoThreadsEnabled=true
 
 # Speculative reads are initiated if a read request doesn't complete within a certain time
 # Using a value of 0, is disabling the speculative reads

pulsar-broker-common/src/main/java/org/apache/pulsar/broker/ServiceConfiguration.java

@@ -2201,9 +2201,10 @@ The max allowed delay for delayed delivery (in milliseconds). If the broker rece
 
     @FieldContext(
             category = CATEGORY_STORAGE_BK,
-            doc = "Use separated IO threads for BookKeeper client. Default is false, which will use Pulsar IO threads"
+            doc = "Use separated IO threads for BookKeeper client. Default is true, which will use dedicated "
+                    + "BookKeeper IO threads"
     )
-    private boolean bookkeeperClientSeparatedIoThreadsEnabled = false;
+    private boolean bookkeeperClientSeparatedIoThreadsEnabled = true;
 
     /**** --- Managed Ledger. --- ****/
     @FieldContext(

pulsar-broker/src/test/java/org/apache/pulsar/broker/BookKeeperClientFactoryImplTest.java

@@ -312,11 +312,11 @@ public void testBookKeeperIoThreadsConfiguration() throws Exception {
         EventLoopGroup eventLoopGroup = mock(EventLoopGroup.class);
         BookKeeper.Builder builder = factory.getBookKeeperBuilder(conf, eventLoopGroup,
                 mock(StatsLogger.class), mock(ClientConfiguration.class));
-        assertEquals(FieldUtils.readField(builder, "eventLoopGroup", true), eventLoopGroup);
-        conf.setBookkeeperClientSeparatedIoThreadsEnabled(true);
+        assertNull(FieldUtils.readField(builder, "eventLoopGroup", true));
+        conf.setBookkeeperClientSeparatedIoThreadsEnabled(false);
         builder = factory.getBookKeeperBuilder(conf, eventLoopGroup,
                 mock(StatsLogger.class), mock(ClientConfiguration.class));
-        assertNull(FieldUtils.readField(builder, "eventLoopGroup", true));
+        assertEquals(FieldUtils.readField(builder, "eventLoopGroup", true), eventLoopGroup);
     }
 
     @Test

pulsar-broker/src/test/java/org/apache/pulsar/common/naming/ServiceConfigurationTest.java

@@ -264,7 +264,7 @@ public void testBookKeeperClientIoThreads() throws Exception {
         try (FileInputStream stream = new FileInputStream("../conf/broker.conf")) {
             final ServiceConfiguration fileConfig =
                     PulsarConfigurationLoader.create(stream, ServiceConfiguration.class);
-            assertFalse(fileConfig.isBookkeeperClientSeparatedIoThreadsEnabled());
+            assertTrue(fileConfig.isBookkeeperClientSeparatedIoThreadsEnabled());
             assertEquals(fileConfig.getBookkeeperClientNumIoThreads(), Runtime.getRuntime().availableProcessors() * 2);
         }
         String confFile = "bookkeeperClientNumIoThreads=1\n"