add an integration test with few available threads

sql/src/test/java/io/crate/integrationtests/ThreadPoolsExhaustedIntegrationTest.java

@@ -0,0 +1,85 @@
+/*
+ * Licensed to Crate.IO GmbH ("Crate") under one or more contributor
+ * license agreements.  See the NOTICE file distributed with this work for
+ * additional information regarding copyright ownership.  Crate 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.
+ *
+ * However, if you have executed another commercial license agreement
+ * with Crate these terms will supersede the license and you may use the
+ * software solely pursuant to the terms of the relevant commercial agreement.
+ */
+
+package io.crate.integrationtests;
+
+import io.crate.action.sql.SQLAction;
+import io.crate.action.sql.SQLRequest;
+import io.crate.action.sql.SQLResponse;
+import org.elasticsearch.action.ActionFuture;
+import org.elasticsearch.common.settings.ImmutableSettings;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.test.ElasticsearchIntegrationTest;
+import org.hamcrest.Matchers;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+@ElasticsearchIntegrationTest.ClusterScope(maxNumDataNodes = 2)
+public class ThreadPoolsExhaustedIntegrationTest extends SQLTransportIntegrationTest {
+
+    @Override
+    protected Settings nodeSettings(int nodeOrdinal) {
+        return ImmutableSettings.settingsBuilder()
+                .put(super.nodeSettings(nodeOrdinal))
+                .put("threadpool.search.size", 2)
+                .put("threadpool.search.queue_size", 2)
+                .build();
+    }
+
+    @Test
+    public void testRegularSelectWithFewAvailableThreadsShouldNeverGetStuck() throws Exception {
+        execute("create table t (x int) with (number_of_replicas = 0)");
+        ensureYellow();
+        bulkInsert(10);
+
+        List<ActionFuture<SQLResponse>> futures = new ArrayList<>();
+        for (int i = 0; i < 1000; i++) {
+            ActionFuture<SQLResponse> future = client().execute(
+                    SQLAction.INSTANCE, new SQLRequest("select * from t limit ?", new Object[] { 10 }));
+            futures.add(future);
+        }
+
+        for (ActionFuture<SQLResponse> future : futures) {
+            try {
+                future.get(500, TimeUnit.MILLISECONDS);
+            } catch (Exception e) {
+                assertThat(e.getMessage(), Matchers.containsString("rejected execution"));
+            }
+        }
+
+        /**
+         * if there is a rejection exception somewhere the query execution is aborted *before*
+         * all contexts are created. We'll leave it up to the context reaper to remove dangling contexts
+         */
+        runJobContextReapers();
+    }
+
+    private void bulkInsert(int docCount) {
+        Object[][] bulkArgs = new Object[docCount][1];
+        for (int i = 0; i < docCount; i++) {
+            bulkArgs[i][0] = i;
+        }
+        execute("insert into t (x) values (?)", bulkArgs);
+    }
+}