Add jitter for the subsequent DNS queries #2170
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Motivation: Current DNS implementation of the `ServiceDiscoverer` sends new queries after each TTL expires. This may lead to spikes in load on DNS servers if many clients align their requests based on the returned TTL value. Modifications: - Add jitter for the subsequent DNS queries; - Allow users to customize jitter value; Result: Subsequent DNS queries are spread out in time using jitter.
tkountis
approved these changes
Apr 5, 2022
...k-dns-discovery-netty/src/main/java/io/servicetalk/dns/discovery/netty/DefaultDnsClient.java
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| // This value is coming from DNS TTL for which the unit is seconds and the minimum value we accept | ||
| // in the builder is 1 second. | ||
| cancellableForQuery = nettyIoExecutor.schedule(this::doQuery0, nanos, NANOSECONDS); | ||
| cancellableForQuery = nettyIoExecutor.schedule(this::doQuery0, delay, NANOSECONDS); |
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It would have been nice to support retry strategies here too, but can't think of an easy way to do so.
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SD retries are handled at client level, bcz it needs visibility into SD errors, see SingleAddressHttpClientBuilder#retryServiceDiscoveryErrors(...).
Don't think we need retry schedule, nettyIoExecutor won't reject unless it's closed.
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Motivation:
Current DNS implementation of the
ServiceDiscoverersends new queriesafter each TTL expires. This may lead to spikes in load on DNS servers
if many clients align their requests based on the returned TTL value.
Modifications:
Result:
Subsequent DNS queries are spread out in time using jitter.