[GitHub] [dubbo] AlbumenJ commented on a diff in pull request #10745: Adaptive loadbalance

[GitBox <gi...@apache.org>]

AlbumenJ commented on code in PR #10745:
URL: https://github.com/apache/dubbo/pull/10745#discussion_r1009968926


##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/support/AdaptiveLoadBalanceFilter.java:
##########
@@ -0,0 +1,150 @@
+/*
+ * 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.dubbo.rpc.cluster.filter.support;
+
+import org.apache.dubbo.common.extension.Activate;
+import org.apache.dubbo.common.profiler.Profiler;
+import org.apache.dubbo.common.profiler.ProfilerEntry;
+import org.apache.dubbo.common.resource.GlobalResourcesRepository;
+import org.apache.dubbo.common.threadlocal.NamedInternalThreadFactory;
+import org.apache.dubbo.common.utils.StringUtils;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.Result;
+import org.apache.dubbo.rpc.RpcException;
+import org.apache.dubbo.rpc.cluster.filter.ClusterFilter;
+import org.apache.dubbo.rpc.cluster.loadbalance.AdaptiveLoadBalance;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.CONSUMER;
+import static org.apache.dubbo.common.constants.CommonConstants.LOADBALANCE_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.COMMA_SPLIT_PATTERN;
+
+/**
+ * if the load balance is adaptive ,set attachment to get the metrics of the server
+ * @see org.apache.dubbo.rpc.Filter
+ * @see org.apache.dubbo.rpc.RpcContext
+ */
+@Activate(group = CONSUMER, order = -200000)

Review Comment:
   ```suggestion
   @Activate(group = CONSUMER, order = -200000, value = {"loadbalance:adaptive"})
   ```



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/support/AdaptiveLoadBalanceFilter.java:
##########
@@ -0,0 +1,150 @@
+/*
+ * 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.dubbo.rpc.cluster.filter.support;
+
+import org.apache.dubbo.common.extension.Activate;
+import org.apache.dubbo.common.profiler.Profiler;
+import org.apache.dubbo.common.profiler.ProfilerEntry;
+import org.apache.dubbo.common.resource.GlobalResourcesRepository;
+import org.apache.dubbo.common.threadlocal.NamedInternalThreadFactory;
+import org.apache.dubbo.common.utils.StringUtils;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.Result;
+import org.apache.dubbo.rpc.RpcException;
+import org.apache.dubbo.rpc.cluster.filter.ClusterFilter;
+import org.apache.dubbo.rpc.cluster.loadbalance.AdaptiveLoadBalance;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.CONSUMER;
+import static org.apache.dubbo.common.constants.CommonConstants.LOADBALANCE_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.COMMA_SPLIT_PATTERN;
+
+/**
+ * if the load balance is adaptive ,set attachment to get the metrics of the server
+ * @see org.apache.dubbo.rpc.Filter
+ * @see org.apache.dubbo.rpc.RpcContext
+ */
+@Activate(group = CONSUMER, order = -200000)
+public class AdaptiveLoadBalanceFilter implements ClusterFilter, ClusterFilter.Listener , ScopeModelAware {
+
+    /**
+     * uses a single worker thread operating off an bounded queue
+     */
+    private ThreadPoolExecutor executor = null;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel) {
+        AdaptiveMetrics bean = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        if (bean == null) {
+            scopeModel.getBeanFactory().registerBean(new AdaptiveMetrics());
+        }
+        this.scopeModel = scopeModel;
+    }
+
+    private ThreadPoolExecutor getExecutor(){
+        if (null == executor) {
+            synchronized (this) {
+                if (null == executor) {
+                    executor = new ThreadPoolExecutor(1, 1, 0L,TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>(1024),
+                        new NamedInternalThreadFactory("Dubbo-framework-loadbalance-adaptive", true), new ThreadPoolExecutor.DiscardOldestPolicy());
+                    GlobalResourcesRepository.getInstance().registerDisposable(() -> this.executor.shutdown());
+                }
+            }
+        }
+        return executor;
+    }
+
+    private AdaptiveMetrics getAdaptiveMetricsInstance(){
+        if (adaptiveMetrics == null) {
+            adaptiveMetrics = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        }
+        return adaptiveMetrics;
+    }

Review Comment:
   move to constructor



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/support/AdaptiveLoadBalanceFilter.java:
##########
@@ -0,0 +1,150 @@
+/*
+ * 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.dubbo.rpc.cluster.filter.support;
+
+import org.apache.dubbo.common.extension.Activate;
+import org.apache.dubbo.common.profiler.Profiler;
+import org.apache.dubbo.common.profiler.ProfilerEntry;
+import org.apache.dubbo.common.resource.GlobalResourcesRepository;
+import org.apache.dubbo.common.threadlocal.NamedInternalThreadFactory;
+import org.apache.dubbo.common.utils.StringUtils;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.Result;
+import org.apache.dubbo.rpc.RpcException;
+import org.apache.dubbo.rpc.cluster.filter.ClusterFilter;
+import org.apache.dubbo.rpc.cluster.loadbalance.AdaptiveLoadBalance;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.CONSUMER;
+import static org.apache.dubbo.common.constants.CommonConstants.LOADBALANCE_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.COMMA_SPLIT_PATTERN;
+
+/**
+ * if the load balance is adaptive ,set attachment to get the metrics of the server
+ * @see org.apache.dubbo.rpc.Filter
+ * @see org.apache.dubbo.rpc.RpcContext
+ */
+@Activate(group = CONSUMER, order = -200000)
+public class AdaptiveLoadBalanceFilter implements ClusterFilter, ClusterFilter.Listener , ScopeModelAware {
+
+    /**
+     * uses a single worker thread operating off an bounded queue
+     */
+    private ThreadPoolExecutor executor = null;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel) {
+        AdaptiveMetrics bean = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        if (bean == null) {
+            scopeModel.getBeanFactory().registerBean(new AdaptiveMetrics());
+        }
+        this.scopeModel = scopeModel;
+    }

Review Comment:
   move to constructor



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/support/AdaptiveLoadBalanceFilter.java:
##########
@@ -0,0 +1,150 @@
+/*
+ * 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.dubbo.rpc.cluster.filter.support;
+
+import org.apache.dubbo.common.extension.Activate;
+import org.apache.dubbo.common.profiler.Profiler;
+import org.apache.dubbo.common.profiler.ProfilerEntry;
+import org.apache.dubbo.common.resource.GlobalResourcesRepository;
+import org.apache.dubbo.common.threadlocal.NamedInternalThreadFactory;
+import org.apache.dubbo.common.utils.StringUtils;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.Result;
+import org.apache.dubbo.rpc.RpcException;
+import org.apache.dubbo.rpc.cluster.filter.ClusterFilter;
+import org.apache.dubbo.rpc.cluster.loadbalance.AdaptiveLoadBalance;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.CONSUMER;
+import static org.apache.dubbo.common.constants.CommonConstants.LOADBALANCE_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.COMMA_SPLIT_PATTERN;
+
+/**
+ * if the load balance is adaptive ,set attachment to get the metrics of the server
+ * @see org.apache.dubbo.rpc.Filter
+ * @see org.apache.dubbo.rpc.RpcContext
+ */
+@Activate(group = CONSUMER, order = -200000)
+public class AdaptiveLoadBalanceFilter implements ClusterFilter, ClusterFilter.Listener , ScopeModelAware {
+
+    /**
+     * uses a single worker thread operating off an bounded queue
+     */
+    private ThreadPoolExecutor executor = null;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel) {
+        AdaptiveMetrics bean = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        if (bean == null) {
+            scopeModel.getBeanFactory().registerBean(new AdaptiveMetrics());
+        }
+        this.scopeModel = scopeModel;
+    }
+
+    private ThreadPoolExecutor getExecutor(){
+        if (null == executor) {
+            synchronized (this) {
+                if (null == executor) {
+                    executor = new ThreadPoolExecutor(1, 1, 0L,TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>(1024),
+                        new NamedInternalThreadFactory("Dubbo-framework-loadbalance-adaptive", true), new ThreadPoolExecutor.DiscardOldestPolicy());
+                    GlobalResourcesRepository.getInstance().registerDisposable(() -> this.executor.shutdown());
+                }
+            }
+        }
+        return executor;
+    }
+
+    private AdaptiveMetrics getAdaptiveMetricsInstance(){
+        if (adaptiveMetrics == null) {
+            adaptiveMetrics = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        }
+        return adaptiveMetrics;
+    }
+
+    @Override
+    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
+        return invoker.invoke(invocation);
+    }
+
+    private String buildServiceKey(Invocation invocation){
+        return invocation.getInvoker().getUrl().getAddress() + ":" + invocation.getProtocolServiceKey();
+        //return url.getAddress() + ProtocolUtils.serviceKey(url.getPort(), url.getPath(), url.getVersion(), url.getGroup());
+    }
+
+    @Override
+    public void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {
+
+        try {
+            if (StringUtils.isNotEmpty(invoker.getUrl().getParameter(LOADBALANCE_KEY))
+                && AdaptiveLoadBalance.NAME.equals(invoker.getUrl().getParameter(LOADBALANCE_KEY))) {
+                getAdaptiveMetricsInstance().addConsumerSuccess(buildServiceKey(invocation));
+            }
+            String attachment = appResponse.getAttachment(Constants.ADAPTIVE_LOADBALANCE_ATTACHMENT_KEY);
+            if (StringUtils.isNotEmpty(attachment)) {
+                String[] parties = COMMA_SPLIT_PATTERN.split(attachment);
+                if (parties.length == 0) {
+                    return;
+                }
+                Map<String, String> metricsMap = new HashMap<>();
+                for (String party : parties) {
+                    String[] groups = party.split(":");
+                    if (groups.length != 2) {
+                        continue;
+                    }
+                    metricsMap.put(groups[0], groups[1]);
+                }
+                ProfilerEntry profilerEntry = (ProfilerEntry) invocation.getAttributes().get(Profiler.PROFILER_KEY);

Review Comment:
   handle NPE if `profilerEntry` is null



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/loadbalance/AdaptiveLoadBalance.java:
##########
@@ -0,0 +1,140 @@
+/*
+ * 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.dubbo.rpc.cluster.loadbalance;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcContext;
+import org.apache.dubbo.rpc.TimeoutCountDown;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+import org.apache.dubbo.rpc.support.RpcUtils;
+
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.TIME_COUNTDOWN_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.DEFAULT_TIMEOUT;
+
+/**
+ * AdaptiveLoadBalance
+ * </p>
+ */
+public class AdaptiveLoadBalance extends AbstractLoadBalance implements ScopeModelAware {
+
+    public static final String NAME = "adaptive";
+
+    //default key
+    private String attachmentKey = "mem,load";
+
+    private final int default_timeout = 30_000;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel){
+        AdaptiveMetrics bean = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        if (bean == null) {
+            scopeModel.getBeanFactory().registerBean(new AdaptiveMetrics());
+        }

Review Comment:
   use `ScopeBeanInitializer`



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/support/AdaptiveLoadBalanceFilter.java:
##########
@@ -0,0 +1,150 @@
+/*
+ * 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.dubbo.rpc.cluster.filter.support;
+
+import org.apache.dubbo.common.extension.Activate;
+import org.apache.dubbo.common.profiler.Profiler;
+import org.apache.dubbo.common.profiler.ProfilerEntry;
+import org.apache.dubbo.common.resource.GlobalResourcesRepository;
+import org.apache.dubbo.common.threadlocal.NamedInternalThreadFactory;
+import org.apache.dubbo.common.utils.StringUtils;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.Result;
+import org.apache.dubbo.rpc.RpcException;
+import org.apache.dubbo.rpc.cluster.filter.ClusterFilter;
+import org.apache.dubbo.rpc.cluster.loadbalance.AdaptiveLoadBalance;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.CONSUMER;
+import static org.apache.dubbo.common.constants.CommonConstants.LOADBALANCE_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.COMMA_SPLIT_PATTERN;
+
+/**
+ * if the load balance is adaptive ,set attachment to get the metrics of the server
+ * @see org.apache.dubbo.rpc.Filter
+ * @see org.apache.dubbo.rpc.RpcContext
+ */
+@Activate(group = CONSUMER, order = -200000)
+public class AdaptiveLoadBalanceFilter implements ClusterFilter, ClusterFilter.Listener , ScopeModelAware {
+
+    /**
+     * uses a single worker thread operating off an bounded queue
+     */
+    private ThreadPoolExecutor executor = null;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel) {
+        AdaptiveMetrics bean = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        if (bean == null) {
+            scopeModel.getBeanFactory().registerBean(new AdaptiveMetrics());
+        }
+        this.scopeModel = scopeModel;
+    }
+
+    private ThreadPoolExecutor getExecutor(){
+        if (null == executor) {
+            synchronized (this) {
+                if (null == executor) {
+                    executor = new ThreadPoolExecutor(1, 1, 0L,TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>(1024),
+                        new NamedInternalThreadFactory("Dubbo-framework-loadbalance-adaptive", true), new ThreadPoolExecutor.DiscardOldestPolicy());
+                    GlobalResourcesRepository.getInstance().registerDisposable(() -> this.executor.shutdown());
+                }
+            }
+        }
+        return executor;
+    }
+
+    private AdaptiveMetrics getAdaptiveMetricsInstance(){
+        if (adaptiveMetrics == null) {
+            adaptiveMetrics = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        }
+        return adaptiveMetrics;
+    }
+
+    @Override
+    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
+        return invoker.invoke(invocation);
+    }
+
+    private String buildServiceKey(Invocation invocation){
+        return invocation.getInvoker().getUrl().getAddress() + ":" + invocation.getProtocolServiceKey();

Review Comment:
   replace to StringBuilder and set initial size to improve performance



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/loadbalance/AdaptiveLoadBalance.java:
##########
@@ -0,0 +1,140 @@
+/*
+ * 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.dubbo.rpc.cluster.loadbalance;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcContext;
+import org.apache.dubbo.rpc.TimeoutCountDown;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+import org.apache.dubbo.rpc.support.RpcUtils;
+
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.TIME_COUNTDOWN_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.DEFAULT_TIMEOUT;
+
+/**
+ * AdaptiveLoadBalance
+ * </p>
+ */
+public class AdaptiveLoadBalance extends AbstractLoadBalance implements ScopeModelAware {
+
+    public static final String NAME = "adaptive";
+
+    //default key
+    private String attachmentKey = "mem,load";
+
+    private final int default_timeout = 30_000;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel){
+        AdaptiveMetrics bean = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        if (bean == null) {
+            scopeModel.getBeanFactory().registerBean(new AdaptiveMetrics());
+        }
+        this.scopeModel = scopeModel;
+    }
+
+    private AdaptiveMetrics getAdaptiveMetricsInstance(){
+        if (adaptiveMetrics == null) {
+            adaptiveMetrics = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        }
+        return adaptiveMetrics;
+    }
+
+    @Override
+    protected <T> Invoker<T> doSelect(List<Invoker<T>> invokers, URL url, Invocation invocation) {
+        Invoker invoker = selectByP2C(invokers,url,invocation);
+        invocation.setAttachment(Constants.ADAPTIVE_LOADBALANCE_ATTACHMENT_KEY,attachmentKey);

Review Comment:
   use `attribute` would better?



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/loadbalance/AdaptiveLoadBalance.java:
##########
@@ -0,0 +1,140 @@
+/*
+ * 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.dubbo.rpc.cluster.loadbalance;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcContext;
+import org.apache.dubbo.rpc.TimeoutCountDown;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+import org.apache.dubbo.rpc.support.RpcUtils;
+
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.TIME_COUNTDOWN_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.DEFAULT_TIMEOUT;
+
+/**
+ * AdaptiveLoadBalance
+ * </p>
+ */
+public class AdaptiveLoadBalance extends AbstractLoadBalance implements ScopeModelAware {
+
+    public static final String NAME = "adaptive";
+
+    //default key
+    private String attachmentKey = "mem,load";
+
+    private final int default_timeout = 30_000;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel){
+        AdaptiveMetrics bean = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        if (bean == null) {
+            scopeModel.getBeanFactory().registerBean(new AdaptiveMetrics());
+        }
+        this.scopeModel = scopeModel;
+    }
+
+    private AdaptiveMetrics getAdaptiveMetricsInstance(){
+        if (adaptiveMetrics == null) {
+            adaptiveMetrics = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        }
+        return adaptiveMetrics;
+    }
+
+    @Override
+    protected <T> Invoker<T> doSelect(List<Invoker<T>> invokers, URL url, Invocation invocation) {
+        Invoker invoker = selectByP2C(invokers,url,invocation);
+        invocation.setAttachment(Constants.ADAPTIVE_LOADBALANCE_ATTACHMENT_KEY,attachmentKey);
+        getAdaptiveMetricsInstance().addConsumerReq(buildServiceKey(invoker,invocation));
+        getAdaptiveMetricsInstance().setPickTime(buildServiceKey(invoker,invocation),System.currentTimeMillis());
+
+        return invoker;
+    }
+
+    private <T> Invoker<T> selectByP2C(List<Invoker<T>> invokers, URL url, Invocation invocation){
+        int length = invokers.size();
+        if(length == 1) {
+            return invokers.get(0);
+        }
+
+        if(length == 2) {
+            return chooseLowLoadInvoker(invokers.get(0),invokers.get(1),invocation);
+        }
+
+        int pos1 = ThreadLocalRandom.current().nextInt(length);
+        int pos2 = ThreadLocalRandom.current().nextInt(length);
+        while(pos1 == pos2) {
+            pos2 = ThreadLocalRandom.current().nextInt(length);
+        }
+
+        return chooseLowLoadInvoker(invokers.get(pos1),invokers.get(pos2),invocation);
+    }
+
+    private String buildServiceKey(Invoker<?> invoker,Invocation invocation){
+        URL url = invoker.getUrl();
+        return url.getAddress() + ":" + invocation.getProtocolServiceKey();
+    }
+
+    private int getTimeout(Invoker<?> invoker, Invocation invocation) {
+        URL url = invoker.getUrl();
+        Object countdown = RpcContext.getClientAttachment().getObjectAttachment(TIME_COUNTDOWN_KEY);
+        int timeout;
+        if (countdown == null) {
+            timeout = (int) RpcUtils.getTimeout(url, invocation.getMethodName(), RpcContext.getClientAttachment(), DEFAULT_TIMEOUT);
+        } else {
+            TimeoutCountDown timeoutCountDown = (TimeoutCountDown) countdown;
+            timeout = (int) timeoutCountDown.timeRemaining(TimeUnit.MILLISECONDS);
+        }
+        return timeout;

Review Comment:
   why read current invocation's timeout?



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/loadbalance/AdaptiveLoadBalance.java:
##########
@@ -0,0 +1,140 @@
+/*
+ * 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.dubbo.rpc.cluster.loadbalance;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcContext;
+import org.apache.dubbo.rpc.TimeoutCountDown;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+import org.apache.dubbo.rpc.support.RpcUtils;
+
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.TIME_COUNTDOWN_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.DEFAULT_TIMEOUT;
+
+/**
+ * AdaptiveLoadBalance
+ * </p>
+ */
+public class AdaptiveLoadBalance extends AbstractLoadBalance implements ScopeModelAware {
+
+    public static final String NAME = "adaptive";
+
+    //default key
+    private String attachmentKey = "mem,load";
+
+    private final int default_timeout = 30_000;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel){
+        AdaptiveMetrics bean = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        if (bean == null) {
+            scopeModel.getBeanFactory().registerBean(new AdaptiveMetrics());
+        }
+        this.scopeModel = scopeModel;
+    }
+
+    private AdaptiveMetrics getAdaptiveMetricsInstance(){
+        if (adaptiveMetrics == null) {
+            adaptiveMetrics = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        }
+        return adaptiveMetrics;
+    }
+
+    @Override
+    protected <T> Invoker<T> doSelect(List<Invoker<T>> invokers, URL url, Invocation invocation) {
+        Invoker invoker = selectByP2C(invokers,url,invocation);
+        invocation.setAttachment(Constants.ADAPTIVE_LOADBALANCE_ATTACHMENT_KEY,attachmentKey);
+        getAdaptiveMetricsInstance().addConsumerReq(buildServiceKey(invoker,invocation));
+        getAdaptiveMetricsInstance().setPickTime(buildServiceKey(invoker,invocation),System.currentTimeMillis());
+
+        return invoker;
+    }
+
+    private <T> Invoker<T> selectByP2C(List<Invoker<T>> invokers, URL url, Invocation invocation){
+        int length = invokers.size();
+        if(length == 1) {
+            return invokers.get(0);
+        }
+
+        if(length == 2) {
+            return chooseLowLoadInvoker(invokers.get(0),invokers.get(1),invocation);
+        }
+
+        int pos1 = ThreadLocalRandom.current().nextInt(length);
+        int pos2 = ThreadLocalRandom.current().nextInt(length);
+        while(pos1 == pos2) {
+            pos2 = ThreadLocalRandom.current().nextInt(length);
+        }
+
+        return chooseLowLoadInvoker(invokers.get(pos1),invokers.get(pos2),invocation);
+    }
+
+    private String buildServiceKey(Invoker<?> invoker,Invocation invocation){
+        URL url = invoker.getUrl();
+        return url.getAddress() + ":" + invocation.getProtocolServiceKey();
+    }
+
+    private int getTimeout(Invoker<?> invoker, Invocation invocation) {
+        URL url = invoker.getUrl();
+        Object countdown = RpcContext.getClientAttachment().getObjectAttachment(TIME_COUNTDOWN_KEY);
+        int timeout;
+        if (countdown == null) {
+            timeout = (int) RpcUtils.getTimeout(url, invocation.getMethodName(), RpcContext.getClientAttachment(), DEFAULT_TIMEOUT);
+        } else {
+            TimeoutCountDown timeoutCountDown = (TimeoutCountDown) countdown;
+            timeout = (int) timeoutCountDown.timeRemaining(TimeUnit.MILLISECONDS);
+        }
+        return timeout;
+    }
+
+    private <T> Invoker<T> chooseLowLoadInvoker(Invoker<T> invoker1,Invoker<T> invoker2,Invocation invocation){
+        int weight1 = getWeight(invoker1, invocation);
+        int weight2 = getWeight(invoker2, invocation);
+        int timeout1 = getTimeout(invoker2, invocation);

Review Comment:
   Are there some spell mistakes?



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/support/AdaptiveLoadBalanceFilter.java:
##########
@@ -0,0 +1,150 @@
+/*
+ * 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.dubbo.rpc.cluster.filter.support;
+
+import org.apache.dubbo.common.extension.Activate;
+import org.apache.dubbo.common.profiler.Profiler;
+import org.apache.dubbo.common.profiler.ProfilerEntry;
+import org.apache.dubbo.common.resource.GlobalResourcesRepository;
+import org.apache.dubbo.common.threadlocal.NamedInternalThreadFactory;
+import org.apache.dubbo.common.utils.StringUtils;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.Result;
+import org.apache.dubbo.rpc.RpcException;
+import org.apache.dubbo.rpc.cluster.filter.ClusterFilter;
+import org.apache.dubbo.rpc.cluster.loadbalance.AdaptiveLoadBalance;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.CONSUMER;
+import static org.apache.dubbo.common.constants.CommonConstants.LOADBALANCE_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.COMMA_SPLIT_PATTERN;
+
+/**
+ * if the load balance is adaptive ,set attachment to get the metrics of the server
+ * @see org.apache.dubbo.rpc.Filter
+ * @see org.apache.dubbo.rpc.RpcContext
+ */
+@Activate(group = CONSUMER, order = -200000)
+public class AdaptiveLoadBalanceFilter implements ClusterFilter, ClusterFilter.Listener , ScopeModelAware {
+
+    /**
+     * uses a single worker thread operating off an bounded queue
+     */
+    private ThreadPoolExecutor executor = null;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel) {
+        AdaptiveMetrics bean = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        if (bean == null) {
+            scopeModel.getBeanFactory().registerBean(new AdaptiveMetrics());

Review Comment:
   Add into `ScopeBeanInitializer`



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/filter/support/AdaptiveLoadBalanceFilter.java:
##########
@@ -0,0 +1,150 @@
+/*
+ * 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.dubbo.rpc.cluster.filter.support;
+
+import org.apache.dubbo.common.extension.Activate;
+import org.apache.dubbo.common.profiler.Profiler;
+import org.apache.dubbo.common.profiler.ProfilerEntry;
+import org.apache.dubbo.common.resource.GlobalResourcesRepository;
+import org.apache.dubbo.common.threadlocal.NamedInternalThreadFactory;
+import org.apache.dubbo.common.utils.StringUtils;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.Result;
+import org.apache.dubbo.rpc.RpcException;
+import org.apache.dubbo.rpc.cluster.filter.ClusterFilter;
+import org.apache.dubbo.rpc.cluster.loadbalance.AdaptiveLoadBalance;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.CONSUMER;
+import static org.apache.dubbo.common.constants.CommonConstants.LOADBALANCE_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.COMMA_SPLIT_PATTERN;
+
+/**
+ * if the load balance is adaptive ,set attachment to get the metrics of the server
+ * @see org.apache.dubbo.rpc.Filter
+ * @see org.apache.dubbo.rpc.RpcContext
+ */
+@Activate(group = CONSUMER, order = -200000)
+public class AdaptiveLoadBalanceFilter implements ClusterFilter, ClusterFilter.Listener , ScopeModelAware {
+
+    /**
+     * uses a single worker thread operating off an bounded queue
+     */
+    private ThreadPoolExecutor executor = null;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel) {

Review Comment:
   replace to constructor



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/loadbalance/AdaptiveLoadBalance.java:
##########
@@ -0,0 +1,140 @@
+/*
+ * 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.dubbo.rpc.cluster.loadbalance;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcContext;
+import org.apache.dubbo.rpc.TimeoutCountDown;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+import org.apache.dubbo.rpc.support.RpcUtils;
+
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.TIME_COUNTDOWN_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.DEFAULT_TIMEOUT;
+
+/**
+ * AdaptiveLoadBalance
+ * </p>
+ */
+public class AdaptiveLoadBalance extends AbstractLoadBalance implements ScopeModelAware {
+
+    public static final String NAME = "adaptive";
+
+    //default key
+    private String attachmentKey = "mem,load";
+
+    private final int default_timeout = 30_000;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel){
+        AdaptiveMetrics bean = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        if (bean == null) {
+            scopeModel.getBeanFactory().registerBean(new AdaptiveMetrics());
+        }
+        this.scopeModel = scopeModel;
+    }

Review Comment:
   move to constructor



##########
dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/loadbalance/AdaptiveLoadBalance.java:
##########
@@ -0,0 +1,140 @@
+/*
+ * 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.dubbo.rpc.cluster.loadbalance;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.rpc.AdaptiveMetrics;
+import org.apache.dubbo.rpc.Constants;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcContext;
+import org.apache.dubbo.rpc.TimeoutCountDown;
+import org.apache.dubbo.rpc.model.ApplicationModel;
+import org.apache.dubbo.rpc.model.ScopeModelAware;
+import org.apache.dubbo.rpc.support.RpcUtils;
+
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+
+import static org.apache.dubbo.common.constants.CommonConstants.TIME_COUNTDOWN_KEY;
+import static org.apache.dubbo.common.constants.CommonConstants.DEFAULT_TIMEOUT;
+
+/**
+ * AdaptiveLoadBalance
+ * </p>
+ */
+public class AdaptiveLoadBalance extends AbstractLoadBalance implements ScopeModelAware {
+
+    public static final String NAME = "adaptive";
+
+    //default key
+    private String attachmentKey = "mem,load";
+
+    private final int default_timeout = 30_000;
+
+    private ApplicationModel scopeModel;
+
+    private AdaptiveMetrics adaptiveMetrics;
+
+    @Override
+    public void setApplicationModel(ApplicationModel scopeModel){
+        AdaptiveMetrics bean = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        if (bean == null) {
+            scopeModel.getBeanFactory().registerBean(new AdaptiveMetrics());
+        }
+        this.scopeModel = scopeModel;
+    }
+
+    private AdaptiveMetrics getAdaptiveMetricsInstance(){
+        if (adaptiveMetrics == null) {
+            adaptiveMetrics = scopeModel.getBeanFactory().getBean(AdaptiveMetrics.class);
+        }
+        return adaptiveMetrics;
+    }
+
+    @Override
+    protected <T> Invoker<T> doSelect(List<Invoker<T>> invokers, URL url, Invocation invocation) {
+        Invoker invoker = selectByP2C(invokers,url,invocation);
+        invocation.setAttachment(Constants.ADAPTIVE_LOADBALANCE_ATTACHMENT_KEY,attachmentKey);
+        getAdaptiveMetricsInstance().addConsumerReq(buildServiceKey(invoker,invocation));
+        getAdaptiveMetricsInstance().setPickTime(buildServiceKey(invoker,invocation),System.currentTimeMillis());
+
+        return invoker;
+    }
+
+    private <T> Invoker<T> selectByP2C(List<Invoker<T>> invokers, URL url, Invocation invocation){
+        int length = invokers.size();
+        if(length == 1) {
+            return invokers.get(0);
+        }
+
+        if(length == 2) {
+            return chooseLowLoadInvoker(invokers.get(0),invokers.get(1),invocation);
+        }
+
+        int pos1 = ThreadLocalRandom.current().nextInt(length);
+        int pos2 = ThreadLocalRandom.current().nextInt(length);
+        while(pos1 == pos2) {
+            pos2 = ThreadLocalRandom.current().nextInt(length);
+        }
+
+        return chooseLowLoadInvoker(invokers.get(pos1),invokers.get(pos2),invocation);
+    }
+
+    private String buildServiceKey(Invoker<?> invoker,Invocation invocation){
+        URL url = invoker.getUrl();
+        return url.getAddress() + ":" + invocation.getProtocolServiceKey();
+    }

Review Comment:
   cache this in invocation attribute



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