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MINOR: Support ExponentialBackoff without jitter #10455

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Merged
cmccabe merged 1 commit into from
Apr 6, 2021
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MINOR: Support ExponentialBackoff without jitter #10455

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3 changes: 2 additions & 1 deletion clients/src/main/java/org/apache/kafka/common/utils/ExponentialBackoff.java
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Original file line number Diff line number Diff line change
Expand Up @@ -47,7 +47,8 @@ public long backoff(long attempts) {
}
double exp = Math.min(attempts, this.expMax);
double term = initialInterval * Math.pow(multiplier, exp);
double randomFactor = ThreadLocalRandom.current().nextDouble(1 - jitter, 1 + jitter);
double randomFactor = jitter < Double.MIN_NORMAL ? 1.0 :

@mumrah mumrah Apr 5, 2021

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I had to look this constant up :)

Can we just make it check if the jitter is equal to zero (or maybe <= zero)? A caller of this method setting jitter to something like 0.5 might be surprised that there is no jitter added.

@cmccabe cmccabe Apr 5, 2021

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MIN_NORMAL is 2^-1022, though. So it certainly wouldn't affect someone setting jitter = 0.5.

@mumrah mumrah Apr 6, 2021

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Gotcha, I misunderstood the docs and thought it was ~1. Let's keep it as-is

ThreadLocalRandom.current().nextDouble(1 - jitter, 1 + jitter);
return (long) (randomFactor * term);
}
}
9 changes: 9 additions & 0 deletions clients/src/test/java/org/apache/kafka/common/utils/ExponentialBackoffTest.java
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Expand Up @@ -45,4 +45,13 @@ public void testExponentialBackoff() {
}
}
}

@Test
public void testExponentialBackoffWithoutJitter() {
ExponentialBackoff exponentialBackoff = new ExponentialBackoff(100, 2, 400, 0.0);
assertEquals(100, exponentialBackoff.backoff(0));
assertEquals(200, exponentialBackoff.backoff(1));
assertEquals(400, exponentialBackoff.backoff(2));
assertEquals(400, exponentialBackoff.backoff(3));
}
}