Jepsen testing (NLnet task 3 subtask 1) #544
5 changed files with 85 additions and 36 deletions
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@ -35,55 +35,74 @@ lein run test --nodes-file nodes.vagrant --time-limit 64 --rate 50 --concurrenc
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### Register linear, without timestamp patch
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Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 20 --concurrency 20 --workload reg1 --ops-per-key 100`
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Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 100 --concurrency 20 --workload reg1 --ops-per-key 100`
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Results: fails with a simple clock-scramble nemesis.
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Results without timestamp patch:
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Explanation: without the timestamp patch, nodes will create objects using their
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local clock only as a timestamp, so the ordering will be all over the place if
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clocks are scrambled.
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- Fails with a simple clock-scramble nemesis (`--scenario c`).
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Explanation: without the timestamp patch, nodes will create objects using their
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local clock only as a timestamp, so the ordering will be all over the place if
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clocks are scrambled.
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### Register linear, with timestamp patch
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Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 20 --concurrency 20 --workload reg1 --ops-per-key 100 --patch tsfix1`
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Results:
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Results with timestamp patch (`--patch tsfix2`):
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- No failure with clock-scramble nemesis
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- Fails with clock-scramble nemesis + partition nemesis
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Explanation: S3 objects are not meant to behave like linearizable registers. TODO explain using a counter-example
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- Fails with clock-scramble nemesis + partition nemesis (`--scenario cp`).
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### Read-after-write CRDT register model, without timestamp patch
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**This test is expected to fail.**
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Indeed, S3 objects are not meant to behave like linearizable registers.
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TODO explain using a counter-example
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### Read-after-write CRDT register model
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Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 100 --concurrency 100 --workload reg2 --ops-per-key 100`
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Results: fails with a simple clock-scramble nemesis.
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Results without timestamp patch:
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Explanation: old values are not overwritten correctly when their timestamps are in the future.
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- Fails with a simple clock-scramble nemesis (`--scenario c`).
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Explanation: old values are not overwritten correctly when their timestamps are in the future.
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### Read-after-write CRDT register model, with timestamp patch (v2 with DeleteObject fix as well)
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Results with timestamp patch (`--patch tsfix2`):
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Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 100 --concurrency 100 --workload reg2 --ops-per-key 100 --patch tsfix2`
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- No failures with clock-scramble nemesis + partition nemesis (`--scenario cp`).
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This proves that `tsfix2` (PR#543) does improve consistency.
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Results:
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- No failures with clock-scramble nemesis + partition nemesis
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- Fails with layout reconfiguration nemesis (TODO: test more and investigate)
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- **Fails with layout reconfiguration nemesis** (`--scenario r`)
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(TODO: note down the run id of a failed run)
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(TODO: test more and investigate).
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This is the failure mode we are looking for and trying to fix for NLnet task 3.
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### Set, basic test (write some items, then read)
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Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 100 --concurrency 100 --workload set1 --ops-per-key 100`
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Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 100 --concurrency 100 --workload set1 --ops-per-key 100 --patch tsfix2`
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Results:
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- For now, no failures with clock-scramble nemesis + partition nemesis
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- TODO: layout reconfiguration nemesis (does not fail yet! but it should)
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- For now, no failures with clock-scramble nemesis + partition nemesis -> TODO long test run
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- Failures were not yet achieved with only the layout reconfiguration nemesis, although they should be.
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- **Fails with partition + layout reconfiguration nemesis** (`--scenario pr`)
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(TODO: note down the run id of a failed run)
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(TODO: test more and investigate).
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This is the failure mode we are looking for and trying to fix for NLnet task 3.
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### Set, continuous test (interspersed reads and writes)
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TODO
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Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 100 --concurrency 100 --workload set2 --ops-per-key 100 --patch tsfix2`
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Results:
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- For now, no failures with clock-scramble nemesis + partition nemesis -> TODO long test run
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- Failures were not yet achieved with only the layout reconfiguration nemesis, although they should be.
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- TODO: failures should be achieved with `--scenario pr`? Even with 4 or 5 consecutive test runs, no failures were achieved, why?
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(TODO: note down the run id of a failed run)
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## Investigating (and fixing) errors
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@ -112,7 +131,7 @@ and passing all values that were previously in the context (creds and prefix) as
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The reg2 test is our custom checker for CRDT read-after-write on individual object keys, acting as registers which can be updated.
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The test fails without the timestamp fix, which is expected as the clock scrambler will prevent nodes from having a correct ordering of objects.
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With the timestamp fix, the happenned-before relationship should at least be respected, meaning that when a PutObject call starts
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With the timestamp fix (`--patch tsfix1`), the happenned-before relationship should at least be respected, meaning that when a PutObject call starts
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after another PutObject call has ended, the second call should overwrite the value of the first call, and that value should not be
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readable by future GetObject calls.
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However, we observed inconsistencies even with the timestamp fix.
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@ -121,7 +140,7 @@ The inconsistencies seemed to always happenned after writing a nil value, which
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instead of a PutObject. By removing the possibility of writing nil values, therefore only doing
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PutObject calls, the issue disappears. There is therefore an issue to fix in DeleteObject.
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The issue in DeleteObject seems to have been fixed by commit `c82d91c6bccf307186332b6c5c6fc0b128b1b2b1`
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The issue in DeleteObject seems to have been fixed by commit `c82d91c6bccf307186332b6c5c6fc0b128b1b2b1`, which can be used using `--patch tsfix2`.
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## License
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@ -23,8 +23,10 @@
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(def scenari
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"A map of scenari to the associated nemesis"
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{"cp" grgNemesis/scenario-cp
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"r" grgNemesis/scenario-r})
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{"c" grgNemesis/scenario-c
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"cp" grgNemesis/scenario-cp
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"r" grgNemesis/scenario-r
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"pr" grgNemesis/scenario-pr})
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(def patches
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"A map of patch names to Garage builds"
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@ -7,6 +7,8 @@
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[jepsen.garage.daemon :as grg]
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[jepsen.control.util :as cu]))
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; ---- reconfiguration nemesis ----
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(defn configure-present!
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"Configure node to be active in new cluster layout"
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[test node]
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@ -61,8 +63,18 @@
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(teardown! [this test] this)))
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; ---- nemesis scenari ----
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(defn scenario-c
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"Clock scramble scenario"
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[opts]
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{:generator (cycle [(gen/sleep 5)
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{:type :info, :f :clock-scramble}])
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:nemesis (nemesis/compose
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{{:clock-scramble :scramble} (nemesis/clock-scrambler 20.0)})})
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(defn scenario-cp
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"Clock scramble + parittion scenario"
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"Clock scramble + partition scenario"
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[opts]
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{:generator (cycle [(gen/sleep 5)
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{:type :info, :f :partition-start}
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@ -91,3 +103,23 @@
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:nemesis (nemesis/compose
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{{:reconfigure-start :start
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:reconfigure-stop :stop} (reconfigure-subset 3)})})
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(defn scenario-pr
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"Partition + cluster reconfiguration scenario"
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[opts]
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{:generator (cycle [(gen/sleep 3)
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{:type :info, :f :reconfigure-start}
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(gen/sleep 3)
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{:type :info, :f :partition-start}
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(gen/sleep 3)
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{:type :info, :f :reconfigure-start}
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(gen/sleep 3)
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{:type :info, :f :partition-stop}
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(gen/sleep 3)
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{:type :info, :f :reconfigure-stop}])
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:final-generator (gen/once {:type :info, :f :partition-stop})
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:nemesis (nemesis/compose
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{{:partition-start :start
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:partition-stop :stop} (nemesis/partition-random-halves)
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{:reconfigure-start :start
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:reconfigure-stop :stop} (reconfigure-subset 3)})})
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@ -39,12 +39,10 @@
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new-object-summaries (:object-summaries list-result)
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new-objects (map (fn [d] (:key d)) new-object-summaries)
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objects (concat new-objects accum)]
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(info (:endpoint creds) "ListObjectsV2 prefix(" prefix "), ct(" ct "): " new-objects)
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(if (:truncated? list-result)
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(list-inner creds prefix (:next-continuation-token list-result) objects)
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objects)))
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(defn list
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"Helper for ListObjects -- just lists everything in the bucket"
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[creds prefix]
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(info "in s3/list creds:" creds ", prefix:" prefix)
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(list-inner creds prefix nil []))
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@ -45,9 +45,7 @@
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10000
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(assoc op :type :fail, :error ::timeout)
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(do
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(info "call s3/list creds: " (:creds this) ", prefix:" prefix)
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(let [items (s3/list (:creds this) prefix)]
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(info "list results for prefix" prefix ":" items " (node:" (:endpoint (:creds this)) ")")
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(let [items-stripped (map (fn [o]
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(assert (str/starts-with? o prefix))
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(str/replace-first o prefix "")) items)
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@ -115,8 +113,8 @@
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{:client (SetClient. nil)
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:checker (independent/checker
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(checker/compose
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{:set-full (checker/set-full {:linearizable? false})
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:set-read-after-write (set-read-after-write)
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{:set-read-after-write (set-read-after-write)
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; :set-full (checker/set-full {:linearizable? false})
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:timeline (timeline/html)}))
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:generator (independent/concurrent-generator
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10
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