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xds, wrr: randomize the initial deadline in the scheduler (#9922)

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yifeizhuang 2023-03-02 15:17:54 -08:00 committed by GitHub
parent 7e41d82b5a
commit c367b267c6
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2 changed files with 30 additions and 14 deletions
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29
xds/src/main/java/io/grpc/xds/WeightedRoundRobinLoadBalancer.java
View File

@ -64,10 +64,10 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
private final Ticker ticker;
public WeightedRoundRobinLoadBalancer(Helper helper, Ticker ticker) {
this(new WrrHelper(OrcaOobUtil.newOrcaReportingHelper(helper)), ticker);
this(new WrrHelper(OrcaOobUtil.newOrcaReportingHelper(helper)), ticker, new Random());
}
public WeightedRoundRobinLoadBalancer(WrrHelper helper, Ticker ticker) {
public WeightedRoundRobinLoadBalancer(WrrHelper helper, Ticker ticker, Random random) {
super(helper);
helper.setLoadBalancer(this);
this.ticker = checkNotNull(ticker, "ticker");
@ -75,7 +75,12 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
this.syncContext = checkNotNull(helper.getSynchronizationContext(), "syncContext");
this.timeService = checkNotNull(helper.getScheduledExecutorService(), "timeService");
this.updateWeightTask = new UpdateWeightTask();
this.random = new Random();
this.random = random;
}
@VisibleForTesting
WeightedRoundRobinLoadBalancer(Helper helper, Ticker ticker, Random random) {
this(new WrrHelper(OrcaOobUtil.newOrcaReportingHelper(helper)), ticker, random);
}
@Override
@ -100,8 +105,7 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
@Override
public RoundRobinPicker createReadyPicker(List<Subchannel> activeList) {
int startIndex = random.nextInt(activeList.size());
return new WeightedRoundRobinPicker(activeList, startIndex);
return new WeightedRoundRobinPicker(activeList);
}
private final class UpdateWeightTask implements Runnable {
@ -228,8 +232,8 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
private volatile EdfScheduler scheduler;
private volatile boolean rrMode;
WeightedRoundRobinPicker(List<Subchannel> list, int startIndex) {
super(checkNotNull(list, "list"), startIndex);
WeightedRoundRobinPicker(List<Subchannel> list) {
super(checkNotNull(list, "list"), random.nextInt(list.size()));
Preconditions.checkArgument(!list.isEmpty(), "empty list");
this.list = list;
updateWeight();
@ -266,7 +270,7 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
rrMode = true;
return;
}
EdfScheduler scheduler = new EdfScheduler(list.size());
EdfScheduler scheduler = new EdfScheduler(list.size(), random);
avgWeight /= 1.0 * weightedChannelCount;
for (int i = 0; i < list.size(); i++) {
WrrSubchannel subchannel = (WrrSubchannel) list.get(i);
@ -348,11 +352,13 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
private final Object lock = new Object();
private final Random random;
/**
* Use the item's deadline as the order in the priority queue. If the deadlines are the same,
* use the index. Index should be unique.
*/
EdfScheduler(int initialCapacity) {
EdfScheduler(int initialCapacity, Random random) {
this.prioQueue = new PriorityQueue<ObjectState>(initialCapacity, (o1, o2) -> {
if (o1.deadline == o2.deadline) {
return Integer.compare(o1.index, o2.index);
@ -360,6 +366,7 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
return Double.compare(o1.deadline, o2.deadline);
}
});
this.random = random;
}
/**
@ -371,8 +378,8 @@ final class WeightedRoundRobinLoadBalancer extends RoundRobinLoadBalancer {
void add(int index, double weight) {
checkArgument(weight > 0.0, "Weights need to be positive.");
ObjectState state = new ObjectState(Math.max(weight, MINIMUM_WEIGHT), index);
state.deadline = 1 / state.weight;
// TODO(zivy): randomize the initial deadline.
// Randomize the initial deadline.
state.deadline = random.nextDouble() * (1 / state.weight);
prioQueue.add(state);
}

15
xds/src/test/java/io/grpc/xds/WeightedRoundRobinLoadBalancerTest.java
View File

@ -171,7 +171,8 @@ public class WeightedRoundRobinLoadBalancerTest {
return subchannel;
}
});
wrr = new WeightedRoundRobinLoadBalancer(helper, fakeClock.getDeadlineTicker());
wrr = new WeightedRoundRobinLoadBalancer(helper, fakeClock.getDeadlineTicker(),
new FakeRandom());
}
@Test
@ -625,7 +626,7 @@ public class WeightedRoundRobinLoadBalancerTest {
double totalWeight = 0;
int capacity = random.nextInt(10) + 1;
double[] weights = new double[capacity];
EdfScheduler scheduler = new EdfScheduler(capacity);
EdfScheduler scheduler = new EdfScheduler(capacity, random);
for (int i = 0; i < capacity; i++) {
weights[i] = random.nextDouble();
scheduler.add(i, weights[i]);
@ -643,7 +644,7 @@ public class WeightedRoundRobinLoadBalancerTest {
@Test
public void edsScheduler_sameWeight() {
EdfScheduler scheduler = new EdfScheduler(2);
EdfScheduler scheduler = new EdfScheduler(2, new FakeRandom());
scheduler.add(0, 0.5);
scheduler.add(1, 0.5);
assertThat(scheduler.pick()).isEqualTo(0);
@ -670,4 +671,12 @@ public class WeightedRoundRobinLoadBalancerTest {
return "FakeSocketAddress-" + name;
}
}
private static class FakeRandom extends Random {
@Override
public double nextDouble() {
// return constant value to disable init deadline randomization in the scheduler
return 0.322023;
}
}
}