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HBASE-26872 Load rate calculator for cost functions should be more precise #4253

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Merged
sunhelly merged 2 commits into from
Mar 27, 2022
Merged

HBASE-26872 Load rate calculator for cost functions should be more precise #4253

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a2d0071
HBASE-26872 Load rate calculator for cost functions should be more pr…
sunhelly Mar 21, 2022
b090103
update the testcase
sunhelly Mar 25, 2022
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4 changes: 2 additions & 2 deletions ...c/main/java/org/apache/hadoop/hbase/master/balancer/CostFromRegionLoadAsRateFunction.java
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Original file line number Diff line number Diff line change
Expand Up @@ -42,9 +42,9 @@ protected double getRegionLoadCost(Collection<BalancerRegionLoad> regionLoadList
double cost = 0;
do {
double current = getCostFromRl(iter.next());
cost += current - previous;
cost += current >= previous ? current - previous : current;
previous = current;
} while (iter.hasNext());
return Math.max(0, cost / (regionLoadList.size() - 1));
}
}
}
28 changes: 26 additions & 2 deletions ...cer/src/test/java/org/apache/hadoop/hbase/master/balancer/TestStochasticLoadBalancer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,6 @@
import static org.junit.Assert.assertTrue;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
Expand Down Expand Up @@ -51,7 +50,6 @@
import org.junit.ClassRule;
import org.junit.Test;
import org.junit.experimental.categories.Category;

import org.apache.hbase.thirdparty.org.apache.commons.collections4.CollectionUtils;

@Category({ MasterTests.class, MediumTests.class })
Expand Down Expand Up @@ -519,6 +517,32 @@ public void testRegionLoadCost() {
assertEquals(2.5, result, 0.01);
}

@Test
public void testRegionLoadCostWhenDecrease() {
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@bbeaudreault bbeaudreault Mar 24, 2022

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correct me if im wrong, but i believe this is testing the case where region loads go 1, 2, 0, 4. So it uses a 0 value in the 3rd slot. This works to verify your change, but I wonder if it would be more comprehensive to test 1, 2, 1, 4. This was just be more indicative of a real reset where the value starts at 0 but then gets incremented again.

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@sunhelly sunhelly Mar 25, 2022

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Yeah, good idea, @bbeaudreault. It's reasonable to test the [1, 2, 1, 4], since it's rare to see 0 in the real scenarios, and I used 0 to describe the issue more clearly. Thanks.

List<BalancerRegionLoad> regionLoads = new ArrayList<>();
// test region loads of [1,2,1,4]
for (int i = 1; i < 5; i++) {
int load = i == 3 ? 1 : i;
BalancerRegionLoad regionLoad = mock(BalancerRegionLoad.class);
when(regionLoad.getReadRequestsCount()).thenReturn((long)load);
when(regionLoad.getCpRequestsCount()).thenReturn((long)load);
regionLoads.add(regionLoad);
}

Configuration conf = HBaseConfiguration.create();
ReadRequestCostFunction readCostFunction =
new ReadRequestCostFunction(conf);
double rateResult = readCostFunction.getRegionLoadCost(regionLoads);
// read requests are treated as a rate so the average rate here is simply 1
assertEquals(1.67, rateResult, 0.01);

CPRequestCostFunction cpCostFunction =
new CPRequestCostFunction(conf);
rateResult = cpCostFunction.getRegionLoadCost(regionLoads);
// coprocessor requests are treated as a rate so the average rate here is simply 1
assertEquals(1.67, rateResult, 0.01);
}

@Test
public void testLosingRs() throws Exception {
int numNodes = 3;
Expand Down