DO not run ES|QL query on transport thread

Author: idegtiarenko

x-pack/plugin/esql/qa/testFixtures/src/main/java/org/elasticsearch/xpack/esql/EsqlTestUtils.java

@@ -25,6 +25,7 @@
 import org.elasticsearch.common.regex.Regex;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.BigArrays;
+import org.elasticsearch.common.util.concurrent.EsExecutors;
 import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.compute.data.AggregateMetricDoubleBlockBuilder;
 import org.elasticsearch.compute.data.BlockFactory;
@@ -43,6 +44,7 @@
 import org.elasticsearch.search.SearchService;
 import org.elasticsearch.tasks.TaskCancelledException;
 import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.RemoteTransportException;
 import org.elasticsearch.transport.TransportService;
 import org.elasticsearch.xcontent.XContentType;
@@ -161,6 +163,8 @@
 import static org.hamcrest.Matchers.instanceOf;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
 
 public final class EsqlTestUtils {
@@ -413,7 +417,7 @@ public static LogicalOptimizerContext unboundLogicalOptimizerContext() {
     public static final Verifier TEST_VERIFIER = new Verifier(new Metrics(new EsqlFunctionRegistry()), new XPackLicenseState(() -> 0L));
 
     public static final TransportActionServices MOCK_TRANSPORT_ACTION_SERVICES = new TransportActionServices(
-        mock(TransportService.class),
+        createMockTransportService(),
         mock(SearchService.class),
         null,
         mock(ClusterService.class),
@@ -423,6 +427,18 @@ public static LogicalOptimizerContext unboundLogicalOptimizerContext() {
         new InferenceService(mock(Client.class))
     );
 
+    private static TransportService createMockTransportService() {
+        var service = mock(TransportService.class);
+        doReturn(createMockThreadPool()).when(service).getThreadPool();
+        return service;
+    }
+
+    private static ThreadPool createMockThreadPool() {
+        var threadPool = mock(ThreadPool.class);
+        doReturn(EsExecutors.DIRECT_EXECUTOR_SERVICE).when(threadPool).executor(anyString());
+        return threadPool;
+    }
+
     private EsqlTestUtils() {}
 
     public static Configuration configuration(QueryPragmas pragmas, String query) {

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/planner/premapper/PreMapper.java

@@ -8,20 +8,26 @@
 package org.elasticsearch.xpack.esql.planner.premapper;
 
 import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.support.ThreadedActionListener;
+import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.xpack.esql.expression.function.fulltext.QueryBuilderResolver;
 import org.elasticsearch.xpack.esql.plan.logical.LogicalPlan;
 import org.elasticsearch.xpack.esql.plugin.TransportActionServices;
 
+import java.util.concurrent.Executor;
+
 /**
  * The class is responsible for invoking any premapping steps that need to be applied to the logical plan,
  * before this is being mapped to a physical one.
  */
 public class PreMapper {
 
     private final TransportActionServices services;
+    private final Executor searchExecutor;
 
     public PreMapper(TransportActionServices services) {
         this.services = services;
+        this.searchExecutor = services.transportService().getThreadPool().executor(ThreadPool.Names.SEARCH);
     }
 
     /**
@@ -35,6 +41,8 @@ public void preMapper(LogicalPlan plan, ActionListener<LogicalPlan> listener) {
     }
 
     private void queryRewrite(LogicalPlan plan, ActionListener<LogicalPlan> listener) {
-        QueryBuilderResolver.resolveQueryBuilders(plan, services, listener);
+        // see https://github.com/elastic/elasticsearch/issues/133312
+        // ThreadedActionListener might be removed if above issue is resolved
+        QueryBuilderResolver.resolveQueryBuilders(plan, services, new ThreadedActionListener<>(searchExecutor, listener));
     }
 }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/session/EsqlSession.java

@@ -34,7 +34,6 @@
 import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.RemoteClusterAware;
 import org.elasticsearch.transport.RemoteClusterService;
-import org.elasticsearch.transport.TcpTransport;
 import org.elasticsearch.xpack.esql.VerificationException;
 import org.elasticsearch.xpack.esql.action.EsqlExecutionInfo;
 import org.elasticsearch.xpack.esql.action.EsqlQueryRequest;
@@ -75,7 +74,6 @@
 import org.elasticsearch.xpack.esql.planner.premapper.PreMapper;
 import org.elasticsearch.xpack.esql.plugin.TransportActionServices;
 import org.elasticsearch.xpack.esql.telemetry.PlanTelemetry;
-import org.elasticsearch.xpack.ml.MachineLearning;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -179,6 +177,7 @@ public void execute(EsqlQueryRequest request, EsqlExecutionInfo executionInfo, P
         analyzedPlan(parsed, executionInfo, request.filter(), new EsqlCCSUtils.CssPartialErrorsActionListener(executionInfo, listener) {
             @Override
             public void onResponse(LogicalPlan analyzedPlan) {
+                assert ThreadPool.assertCurrentThreadPool(ThreadPool.Names.SEARCH, ThreadPool.Names.SEARCH_COORDINATION);
                 SubscribableListener.<LogicalPlan>newForked(l -> preOptimizedPlan(analyzedPlan, l))
                     .<LogicalPlan>andThen((l, p) -> preMapper.preMapper(optimizedPlan(p), l))
                     .<Result>andThen((l, p) -> executeOptimizedPlan(request, executionInfo, planRunner, p, l))
@@ -198,13 +197,7 @@ public void executeOptimizedPlan(
         LogicalPlan optimizedPlan,
         ActionListener<Result> listener
     ) {
-        assert ThreadPool.assertCurrentThreadPool(
-            TcpTransport.TRANSPORT_WORKER_THREAD_NAME_PREFIX,
-            ThreadPool.Names.SYSTEM_READ,
-            ThreadPool.Names.SEARCH,
-            ThreadPool.Names.SEARCH_COORDINATION,
-            MachineLearning.NATIVE_INFERENCE_COMMS_THREAD_POOL_NAME
-        );
+        assert ThreadPool.assertCurrentThreadPool(ThreadPool.Names.SEARCH, ThreadPool.Names.SEARCH_COORDINATION);
         if (explainMode) {// TODO: INLINESTATS come back to the explain mode branch and reevaluate
             PhysicalPlan physicalPlan = logicalPlanToPhysicalPlan(optimizedPlan, request);
             String physicalPlanString = physicalPlan.toString();