Jepsen Files

This release focuses on generator performance and correctness, and introduces several new generators. It also improves the web interface and fixes some long-standing issues with time zones.

Bugfixes

• generator/process-limit could crash when it received an update before being asked for an operation.
• generator/process-limit can now limit to fewer processes than there are available threads.
• generator/reserve now nests properly within other reserves, or other generators which restrict threads.
• generator/limit no longer counts down the limit when operations are :pending.
• checker/counter now ignores nemesis operations

API Changes

• generator/stagger now uses an exponential, rather than uniform distribution of delays between operations. You often want very short and much longer delays between operations, especially for nemeses; now stagger will produce these.
• jepsen.generator now uses jepsen.random throughout. This shouldn't affect tests of actual databases (since the values are similarly random), but it will change the deterministic pseudorandom choices observed by tests of the generators themselves.
• Jepsen test directories and files now include time zones. This makes them properly portable across different zones.
• checker/set considers empty histories valid; this makes it easier to check independent sets even when the database is down for the full duration of a key.

New Features

• generator/track: keeps track of some value extracted from each operation.
• generator/until: a generalized version of until-ok
• generator/relaxed-reconnect: when a thread can't open a client, give it a short rest
• A new CLI option --seed provides some degree of replayable deterministic randomness
• independent/track-keys and final-generator let you perform some final operation at the end of a test across all keys.
• The web interface now lets you preview and browse test.jepsen files; it shows the test map without :results or :history.

Minor Changes

• generator.interpreter now updates its generator when operations are :pending. This significantly improves performance by allowing expensive computations, like functions used as generators, to be memoized rather than re-evaluated many times in a row.
• cli/parse-concurrency now allows nil; this is helpful when workloads want to suggest their own concurrencies.
• Jepsen no longer depends on Joda Time; we now use java.time throughout.
• The web interface now displays times in the local time zone
• The web interface no longer caches incomplete tests.
• tests.cycle uses the new track generator to keep track of its maximum keys.
• Clojure 1.12.6
• SSHJ 0.41.1