#1202 - Automatically remove old query plans from Ebean's internal query plan cache

src/main/java/io/ebean/config/ServerConfig.java

@@ -435,6 +435,11 @@ public class ServerConfig {
 
   private String jodaLocalTimeMode;
 
+  /**
+   * Time to live for query plans - defaults to 5 minutes.
+   */
+  private int queryPlanTTLSeconds = 60 * 5;
+
   /**
    * Set to true to globally disable L2 caching (typically for performance testing).
    */
@@ -2595,6 +2600,7 @@ public class ServerConfig {
       dbTypeConfig.setGeometrySRID(srid);
     }
 
+    queryPlanTTLSeconds = p.getInt("queryPlanTTLSeconds", queryPlanTTLSeconds);
     slowQueryMillis = p.getLong("slowQueryMillis", slowQueryMillis);
     docStoreOnly = p.getBoolean("docStoreOnly", docStoreOnly);
     disableL2Cache = p.getBoolean("disableL2Cache", disableL2Cache);
@@ -2817,6 +2823,20 @@ public class ServerConfig {
     this.disableL2Cache = disableL2Cache;
   }
 
+  /**
+   * Return the query plan time to live.
+   */
+  public int getQueryPlanTTLSeconds() {
+    return queryPlanTTLSeconds;
+  }
+
+  /**
+   * Set the query plan time to live.
+   */
+  public void setQueryPlanTTLSeconds(int queryPlanTTLSeconds) {
+    this.queryPlanTTLSeconds = queryPlanTTLSeconds;
+  }
+
   /**
    * Run the DB migration against the DataSource.
    */

src/main/java/io/ebeaninternal/server/core/InternalConfiguration.java

@@ -151,6 +151,7 @@ public class InternalConfiguration {
     this.beanDescriptorManager = new BeanDescriptorManager(this);
     Map<String, String> asOfTableMapping = beanDescriptorManager.deploy();
     Map<String, String> draftTableMap = beanDescriptorManager.getDraftTableMap();
+    beanDescriptorManager.scheduleBackgroundTrim();
 
     this.dataTimeZone = initDataTimeZone();
     this.binder = getBinder(typeManager, databasePlatform, dataTimeZone);

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptor.java

@@ -89,6 +89,7 @@ import java.sql.Types;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -1530,6 +1531,24 @@ public class BeanDescriptor<T> implements MetaBeanInfo, BeanType<T> {
     }
   }
 
+  /**
+   * Trim query plans not used since the passed in epoch time.
+   */
+  public List<CQueryPlan> trimQueryPlans(long unusedSince) {
+
+    List<CQueryPlan> list = new ArrayList<>();
+
+    Iterator<CQueryPlan> it = queryPlanCache.values().iterator();
+    while (it.hasNext()) {
+      CQueryPlan queryPlan = it.next();
+      if (queryPlan.getLastQueryTime() < unusedSince) {
+        it.remove();
+        list.add(queryPlan);
+      }
+    }
+    return list;
+  }
+
   /**
    * Execute the postLoad if a BeanPostLoad exists for this bean.
    */

src/main/java/io/ebeaninternal/server/deploy/BeanDescriptorManager.java

@@ -49,6 +49,7 @@ import io.ebeaninternal.server.persist.platform.MultiValueBind;
 import io.ebeaninternal.server.properties.BeanPropertiesReader;
 import io.ebeaninternal.server.properties.BeanPropertyAccess;
 import io.ebeaninternal.server.properties.EnhanceBeanPropertyAccess;
+import io.ebeaninternal.server.query.CQueryPlan;
 import io.ebeaninternal.xmlmapping.XmlMappingReader;
 import io.ebeaninternal.xmlmapping.model.XmAliasMapping;
 import io.ebeaninternal.xmlmapping.model.XmColumnMapping;
@@ -80,6 +81,7 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.TimeUnit;
 import java.util.stream.Collectors;
 
 /**
@@ -190,6 +192,8 @@ public class BeanDescriptorManager implements BeanDescriptorMap {
    */
   private final Map<String, String> draftTableMap = new HashMap<>();
 
+  private final int queryPlanTTLSeconds;
+
   /**
    * Create for a given database dbConfig.
    */
@@ -207,6 +211,7 @@ public class BeanDescriptorManager implements BeanDescriptorMap {
     this.multiValueBind = config.getMultiValueBind();
     this.idBinderFactory = new IdBinderFactory(databasePlatform.isIdInExpandedForm(), multiValueBind);
     this.eagerFetchLobs = serverConfig.isEagerFetchLobs();
+    this.queryPlanTTLSeconds = serverConfig.getQueryPlanTTLSeconds();
 
     this.asOfViewSuffix = getAsOfViewSuffix(databasePlatform, serverConfig);
     String versionsBetweenSuffix = getVersionsBetweenSuffix(databasePlatform, serverConfig);
@@ -236,6 +241,25 @@ public class BeanDescriptorManager implements BeanDescriptorMap {
     this.changeLogRegister = config.changeLogRegister(bootupClasses.getChangeLogRegister());
   }
 
+  /**
+   * Run periodic trim of query plans.
+   */
+  public void scheduleBackgroundTrim() {
+    backgroundExecutor.executePeriodically(this::trimQueryPlans, 30L, TimeUnit.SECONDS);
+  }
+
+  private void trimQueryPlans() {
+    long lastUsed = System.currentTimeMillis() - (queryPlanTTLSeconds * 1000L);
+    for (BeanDescriptor<?> descriptor : immutableDescriptorList) {
+      if (!descriptor.isEmbedded()) {
+        List<CQueryPlan> trimmedPlans = descriptor.trimQueryPlans(lastUsed);
+        if (!trimmedPlans.isEmpty()) {
+          logger.trace("trimmed {} query plans for type:{}", trimmedPlans.size(), descriptor.getName());
+        }
+      }
+    }
+  }
+
   /**
    * Return the AsOfViewSuffix based on the DbHistorySupport.
    */

src/main/java/io/ebeaninternal/server/query/CQueryBuilder.java

@@ -252,7 +252,7 @@ class CQueryBuilder {
       // skip building the SqlTree and Sql string
       predicates.prepare(false);
       String sql = queryPlan.getSql();
-      return new CQueryRowCount(request, predicates, sql);
+      return new CQueryRowCount(queryPlan, request, predicates, sql);
     }
 
     predicates.prepare(true);
@@ -283,7 +283,7 @@ class CQueryBuilder {
     queryPlan = new CQueryPlan(request, sql, sqlTree, false, s.isIncludesRowNumberColumn(), predicates.getLogWhereSql());
     request.putQueryPlan(queryPlan);
 
-    return new CQueryRowCount(request, predicates, sql);
+    return new CQueryRowCount(queryPlan, request, predicates, sql);
   }
 
   /**

src/main/java/io/ebeaninternal/server/query/CQueryRowCount.java

@@ -16,6 +16,8 @@ import java.sql.SQLException;
  */
 class CQueryRowCount {
 
+  private final CQueryPlan queryPlan;
+
   /**
    * The overall find request wrapper object.
    */
@@ -54,7 +56,8 @@ class CQueryRowCount {
   /**
    * Create the Sql select based on the request.
    */
-  CQueryRowCount(OrmQueryRequest<?> request, CQueryPredicates predicates, String sql) {
+  CQueryRowCount(CQueryPlan queryPlan, OrmQueryRequest<?> request, CQueryPredicates predicates, String sql) {
+    this.queryPlan = queryPlan;
     this.request = request;
     this.query = request.getQuery();
     this.sql = sql;
@@ -116,6 +119,7 @@ class CQueryRowCount {
       rowCount = rset.getInt(1);
 
       executionTimeMicros = (System.nanoTime() - startNano) / 1000L;
+      queryPlan.executionTime(rowCount, executionTimeMicros, query.getParentNode());
       request.slowQueryCheck(executionTimeMicros, rowCount);
       return rowCount;