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https://issues.apache.org/jira/browse/PHOENIX-5069?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16736532#comment-16736532
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ASF GitHub Bot commented on PHOENIX-5069:
-----------------------------------------
Github user BinShi-SecularBird commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/425#discussion_r245847642
--- Diff:
phoenix-core/src/test/java/org/apache/phoenix/query/PhoenixStatsCacheLoaderTest.java
---
@@ -0,0 +1,123 @@
+/*
+ * 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 static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.LoadingCache;
+import com.google.common.cache.Weigher;
+import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
+import org.apache.phoenix.schema.stats.GuidePostsInfo;
+import org.apache.phoenix.schema.stats.GuidePostsKey;
+import org.apache.phoenix.util.ByteUtil;
+import org.junit.Test;
+
+import java.lang.Thread;
+import java.util.Collections;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.ExecutorService;
+
+/**
+ * Test class around the PhoenixStatsCacheLoader.
+ */
+public class PhoenixStatsCacheLoaderTest {
+ /**
+ * {@link PhoenixStatsLoader} test implementation for the Stats Loader.
+ */
+ protected class TestStatsLoaderImpl implements PhoenixStatsLoader {
+ private int maxLength = 1;
+
+ @Override
+ public boolean needsLoad() {
+ // Whenever it's called, we try to load stats from stats table
+ // no matter it has been updated or not.
+ return true;
+ }
+
+ @Override
+ public GuidePostsInfo loadStats(GuidePostsKey statsKey,
GuidePostsInfo prevGuidepostInfo) throws Exception {
+ try {
+ Thread.sleep(2000);
+ }
+ catch (InterruptedException e) {
+ assertFalse(true);
+ }
+
+ return new GuidePostsInfo(Collections.<Long> emptyList(),
+ new ImmutableBytesWritable(ByteUtil.EMPTY_BYTE_ARRAY),
+ Collections.<Long> emptyList(), maxLength++, 0,
Collections.<Long> emptyList());
+ }
+ }
+
+ GuidePostsInfo getStats(LoadingCache<GuidePostsKey, GuidePostsInfo>
cache, GuidePostsKey guidePostsKey) {
+ GuidePostsInfo guidePostsInfo;
+ try {
+ guidePostsInfo = cache.get(guidePostsKey);
+ } catch (ExecutionException e) {
+ assertFalse(true);
+ return GuidePostsInfo.NO_GUIDEPOST;
+ }
+
+ return guidePostsInfo;
+ }
+
+ void sleep(int x) {
+ try {
+ Thread.sleep(x);
+ }
+ catch (InterruptedException e) {
+ assertFalse(true);
+ }
+ }
+
+ @Test
+ public void testStatsBeingAutomaticallyRefreshed() {
+ ExecutorService executor = Executors.newFixedThreadPool(4);
+
+ LoadingCache<GuidePostsKey, GuidePostsInfo> cache =
CacheBuilder.newBuilder()
+ // Refresh entries a given amount of time after they were
written
+ .refreshAfterWrite(1000, TimeUnit.MILLISECONDS)
+ // Maximum total weight (size in bytes) of stats entries
+
.maximumWeight(QueryServicesOptions.DEFAULT_STATS_MAX_CACHE_SIZE)
+ // Defer actual size to the PTableStats.getEstimatedSize()
+ .weigher(new Weigher<GuidePostsKey, GuidePostsInfo>() {
+ @Override public int weigh(GuidePostsKey key,
GuidePostsInfo info) {
+ return info.getEstimatedSize();
+ }
+ })
+ // Log removals at TRACE for debugging
+ .removalListener(new
GuidePostsCache.PhoenixStatsCacheRemovalListener())
+ // Automatically load the cache when entries are missing
+ .build(new PhoenixStatsCacheLoader(new
TestStatsLoaderImpl(), executor));
+
+ GuidePostsKey guidePostsKey = new GuidePostsKey(new byte[4], new
byte[4]);
+ GuidePostsInfo guidePostsInfo = getStats(cache, guidePostsKey);
+ assertTrue(guidePostsInfo.getMaxLength() == 1);
+ sleep(3000);
+ guidePostsInfo = getStats(cache, guidePostsKey);
--- End diff --
Comment from @twdsilva (copied from prev PR #416): Instead of relying on
sleep which tends to cause tests to fail on the build machines, can you use a
latch or some other mechanism to determine that the guideposts have been
refreshed?
> 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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