This version does not have any known bugs, but is not recommended for production use until 1.5.0.
The general premise of this release is to make metrics more flexible within Hystrix. See https://github.com/Netflix/Hystrix/wiki/Metrics-and-Monitoring for a deep dive on the new metrics architecture. The high-level view is to make the metrics primitive a stream instead of an aggregate. In 1.4.x and prior releases, HystrixRollingNumber and HystrixRollingPercentile were used to store aggregate command counters and command latencies, respectively. These are no longer used.
Instead, new concepts like HystrixCommandCompletionStream are present. These may be consumed by a rolling, summarizing data structure (like HystrixRollingNumber), or they may be consumed without any aggregation at all. This should allow for all metrics processing to move off-box, if you desire to add that piece to your infrastructure.
This version should be backwards-compatible with v1.4.x. If you find otherwise, please submit a Hystrix issue as it was unintentional.
Some known semantic changes:
- Latencies for timeouts and bad-requests are now included in command latency
- Latency distribution percentiles are now calculated with HdrHistogram library and don't have a max number of elements in the distribution
- Previously, HealthCounts data allowed reads to see the value in the "hot" bucket. (the one currently being written to). That does not happen anymore - only full read-only buckets are available for reads.
- Bucket rolling now happens via Rx background threads instead of unlucky Hystrix command threads. This makes command performance more predictable. User-thread latency is now practically indistinguishable from command latency.
Artifacts: Maven Central, Bintray