[GitHub] [ignite-3] ygerzhedovich commented on a change in pull request #652: IGNITE-16502 fixed deadlock caused by query plan cache

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

ygerzhedovich commented on a change in pull request #652:
URL: https://github.com/apache/ignite-3/pull/652#discussion_r803862434



##########
File path: modules/sql-engine/src/main/java/org/apache/ignite/internal/sql/engine/prepare/QueryPlanCacheImpl.java
##########
@@ -18,50 +18,99 @@
 package org.apache.ignite.internal.sql.engine.prepare;
 
 import com.github.benmanes.caffeine.cache.Caffeine;
-import java.util.Map;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
 import java.util.function.Supplier;
+import org.apache.ignite.internal.thread.NamedThreadFactory;
 
 /**
  * Implementation of {@link QueryPlanCache} that simply wraps a {@link Caffeine} cache.
  */
 public class QueryPlanCacheImpl implements QueryPlanCache {
-    private final ConcurrentMap<CacheKey, QueryPlan> cache;
+    private static final long THREAD_TIMEOUT_MS = 60_000;
+
+    private final ConcurrentMap<CacheKey, CompletableFuture<QueryPlan>> cache;
+
+    private final ThreadPoolExecutor planningPool;
+
+    private final BlockingQueue<Runnable> planningTasks = new LinkedBlockingQueue<>();
+
+    private final ReadWriteLock lock = new ReentrantReadWriteLock();
 
     /**
      * Creates a plan cache of provided size.
      *
      * @param cacheSize Desired cache size.
      */
-    public QueryPlanCacheImpl(int cacheSize) {
+    public QueryPlanCacheImpl(String nodeName, int cacheSize) {
+        planningPool = new ThreadPoolExecutor(
+                4,
+                4,
+                THREAD_TIMEOUT_MS,
+                TimeUnit.MILLISECONDS,
+                planningTasks,
+                new NamedThreadFactory(NamedThreadFactory.threadPrefix(nodeName, "sqlPlan"))
+        );
+
+        planningPool.allowCoreThreadTimeOut(true);
+
         cache = Caffeine.newBuilder()
                 .maximumSize(cacheSize)
-                .<CacheKey, QueryPlan>build()
+                .<CacheKey, CompletableFuture<QueryPlan>>build()
                 .asMap();
     }
 
     /** {@inheritDoc} */
     @Override
     public QueryPlan queryPlan(CacheKey key, Supplier<QueryPlan> planSupplier) {
-        Map<CacheKey, QueryPlan> cache = this.cache;
-        QueryPlan plan = cache.computeIfAbsent(key, k -> planSupplier.get());
+        lock.readLock().lock();
 
-        return plan.copy();
+        CompletableFuture<QueryPlan> planFut;
+        try {
+            planFut = cache.computeIfAbsent(key, k -> CompletableFuture.supplyAsync(planSupplier, planningPool));
+        } finally {
+            lock.readLock().unlock();
+        }
+
+        return planFut.join().copy();
     }
 
     /** {@inheritDoc} */
     @Override
     public QueryPlan queryPlan(CacheKey key) {
-        Map<CacheKey, QueryPlan> cache = this.cache;
-        QueryPlan plan = cache.get(key);
+        lock.readLock().lock();

Review comment:
       why not write lock?




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