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https://issues.apache.org/jira/browse/PHOENIX-5069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16736561#comment-16736561
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ASF GitHub Bot commented on PHOENIX-5069:
-----------------------------------------
Github user karanmehta93 commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/425#discussion_r245853048
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/query/PhoenixStatsCacheLoader.java
---
@@ -0,0 +1,73 @@
+/*
+ * 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.phoenix.query;
+
+import com.google.common.cache.CacheLoader;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.google.common.util.concurrent.ListenableFutureTask;
+import org.apache.phoenix.schema.stats.GuidePostsInfo;
+import org.apache.phoenix.schema.stats.GuidePostsKey;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+
+/**
+ * {@link CacheLoader} implementation for the Phoenix Table Stats cache.
+ */
+public class PhoenixStatsCacheLoader extends CacheLoader<GuidePostsKey,
GuidePostsInfo> {
+ private static final Logger logger =
LoggerFactory.getLogger(PhoenixStatsCacheLoader.class);
+
+ final private PhoenixStatsLoader statsLoader;
+ final private ExecutorService executor;
+
+ public PhoenixStatsCacheLoader(PhoenixStatsLoader statsLoader,
ExecutorService executor) {
+ super();
+ this.statsLoader = statsLoader;
+ this.executor = executor;
+ }
+
+ @Override
+ public GuidePostsInfo load(GuidePostsKey statsKey) throws Exception {
+ return statsLoader.loadStats(statsKey,
GuidePostsInfo.NO_GUIDEPOST);
+ }
+
+ @Override
+ public ListenableFuture<GuidePostsInfo> reload(
+ final GuidePostsKey key,
+ GuidePostsInfo prevGuidepostInfo)
+ {
+ // schedule asynchronous task
+ ListenableFutureTask<GuidePostsInfo> task =
--- End diff --
Even though currently `StatsLoaderImpl#needsLoad()` is hardcoded to true,
it still should be called here first.
> Use asynchronous refresh to provide non-blocking Phoenix Stats Client Cache
> ---------------------------------------------------------------------------
>
> Key: PHOENIX-5069
> URL: https://issues.apache.org/jira/browse/PHOENIX-5069
> Project: Phoenix
> Issue Type: Improvement
> Reporter: Bin Shi
> Assignee: Bin Shi
> Priority: Major
>
> The current Phoenix Stats Cache uses TTL based eviction policy. A cached
> entry will expire after a given amount of time (900s by default) passed since
> the entry's been created. This will lead to cache miss when
> Compiler/Optimizer fetches stats from cache at the next time. As you can see
> from the above graph, fetching stats from the cache is a blocking operation —
> when there is cache miss, it has a round trip over the wire to scan the
> SYSTEM.STATS Table and to get the latest stats info, rebuild the cache and
> finally return the stats to the Compiler/Optimizer. Whenever there is a cache
> miss, this blocking call causes significant performance penalty and see
> periodic spikes.
> *This Jira suggests to use asynchronous refresh mechanism to provide a
> non-blocking cache. For details, please see the linked design document below.*
> [~karanmehta93] [[email protected]] [~dbwong] [~elserj] [[email protected]]
> [~sergey soldatov]
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