wchevreuil commented on code in PR #8197:
URL: https://github.com/apache/hbase/pull/8197#discussion_r3202011996
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hbase-server/src/test/java/org/apache/hadoop/hbase/master/balancer/TestCacheAwareLoadBalancerCostFunctions.java:
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@@ -251,12 +263,105 @@ public void testCacheCost() {
}
}
+ /**
+ * When block-cache persistence, cold regions (below
+ * {@link CacheAwareLoadBalancer#LOW_CACHE_RATIO_FOR_RELOCATION_KEY})
together with RS-reported
+ * block-cache free bytes inflate plausible best placement so weighted cache
cost crosses
+ * {@code minCostNeedBalance}; {@link StochasticLoadBalancer#needsBalance}
returns true even with
+ * evenly spread region-count skew.
+ */
+ @Test
+ public void testNeedsBalanceWhenLowCacheRatioRegionsAndFreeBlockCacheSpace()
{
+ conf.set(HConstants.BUCKET_CACHE_PERSISTENT_PATH_KEY,
"/tmp/prefetch.persistence");
+ CacheAwareLoadBalancer lb = newCacheAwareBalancer(conf);
+ int regionSizeMb = 64;
+ long cacheFreeInBytes = regionSizeMb * 1024L * 1024L;
+ // simulates a cache ratio lower than
+ // CacheAwareLoadBalancer.LOW_CACHE_RATIO_FOR_RELOCATION_DEFAULT
+ float simulatedCacheRatio = 0.1f;
+ Map<ServerName, List<RegionInfo>> clusterServers =
+ mockClusterServersUnsorted(new int[] { 1, 1 }, 1);
+ List<RegionInfo> regions = new ArrayList<>();
+ clusterServers.values().forEach(regions::addAll);
+ List<ServerName> serversList = getServersInInsertionOrder(clusterServers);
+ Map<ServerName, Long> blockCacheFree = new HashMap<>();
+ blockCacheFree.put(serversList.get(0), 0L);
+ blockCacheFree.put(serversList.get(1), cacheFreeInBytes);
+ BalancerClusterState cluster = new BalancerClusterState(clusterServers,
+ buildRegionLoads(regions, simulatedCacheRatio, regionSizeMb), null, null,
+ Collections.emptyMap(), blockCacheFree);
+ lb.initCosts(cluster);
+ assertTrue(lb.needsBalance(
+
TableName.valueOf("testNeedsBalanceWhenLowCacheRatioRegionsAndFreeBlockCacheSpace"),
+ cluster));
+ }
+
+ /**
+ * Checks that needsBalance isn't true when regions report high cache ratios
+ */
+ @Test
+ public void testNeedsBalanceFalseWhenWarmRegionsDespiteFreeBlockCacheSpace()
{
+ conf.set(HConstants.BUCKET_CACHE_PERSISTENT_PATH_KEY,
"/tmp/prefetch.persistence");
+ CacheAwareLoadBalancer lb = newCacheAwareBalancer(conf);
+ int regionSizeMb = 64;
+ long cacheFreeInBytes = regionSizeMb * 1024L * 1024L;
+ Map<ServerName, List<RegionInfo>> clusterServers =
+ mockClusterServersUnsorted(new int[] { 1, 1 }, 1);
+ List<RegionInfo> all = new ArrayList<>();
+ clusterServers.values().forEach(all::addAll);
+ List<ServerName> serversList = getServersInInsertionOrder(clusterServers);
+ Map<ServerName, Long> blockCacheFree = new HashMap<>();
+ blockCacheFree.put(serversList.get(0), cacheFreeInBytes + 1024 * 1024);
+ blockCacheFree.put(serversList.get(1), cacheFreeInBytes + 1024 * 1024);
+ BalancerClusterState cluster =
+ new BalancerClusterState(clusterServers, buildRegionLoads(all, 1.0f,
regionSizeMb), null,
+ null, Collections.emptyMap(), blockCacheFree);
+ lb.initCosts(cluster);
+ assertFalse(lb.needsBalance(
+
TableName.valueOf("testNeedsBalanceFalseWhenWarmRegionsDespiteFreeBlockCacheSpace"),
+ cluster));
+ }
+
+ private static CacheAwareLoadBalancer newCacheAwareBalancer(Configuration
cfg) {
+ CacheAwareLoadBalancer lb = new CacheAwareLoadBalancer();
+ lb.setClusterInfoProvider(new DummyClusterInfoProvider(cfg));
+ lb.loadConf(cfg);
+ return lb;
+ }
+
+ private static Map<String, Deque<BalancerRegionLoad>>
+ buildRegionLoads(Collection<RegionInfo> regions, float cachedRatio, int
regionSizeMb) {
+ RegionMetrics rm = mock(RegionMetrics.class);
+ when(rm.getReadRequestCount()).thenReturn(0L);
+ when(rm.getCpRequestCount()).thenReturn(0L);
+ when(rm.getWriteRequestCount()).thenReturn(0L);
+ when(rm.getMemStoreSize()).thenReturn(Size.ZERO);
+ when(rm.getStoreFileSize()).thenReturn(Size.ZERO);
+ when(rm.getRegionSizeMB()).thenReturn(new Size(regionSizeMb,
Size.Unit.MEGABYTE));
+ when(rm.getCurrentRegionCachedRatio()).thenReturn(cachedRatio);
+
+ BalancerRegionLoad brl = new BalancerRegionLoad(rm);
+ Map<String, Deque<BalancerRegionLoad>> loads = new HashMap<>();
+ for (RegionInfo ri : regions) {
+ ArrayDeque<BalancerRegionLoad> dq = new ArrayDeque<>(1);
+ dq.add(brl);
+ loads.put(ri.getRegionNameAsString(), dq);
+ loads.put(ri.getEncodedName(), dq);
+ }
+ return loads;
+ }
+
+ private static List<ServerName>
+ getServersInInsertionOrder(Map<ServerName, List<RegionInfo>> cluster) {
+ return new ArrayList<>(cluster.keySet());
+ }
Review Comment:
Well, we have entire control over the map implementation instance passed
from our tests, which is a LinkedHashMap, so no need to worry about this here.
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