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Jepsen testing (NLnet task 3 subtask 1) #544

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lx merged 41 commits from jepsen into main 2024-01-11 10:52:13 +00:00
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37
script/jepsen.garage/README.md
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@ -33,7 +33,7 @@ lein run test --nodes-file nodes.vagrant --time-limit 64 --rate 50 --concurrenc
## Results
**Register linear, without timestamp patch**
### Register linear, without timestamp patch
Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 20 --concurrency 20 --workload reg --ops-per-key 100`
@ -43,7 +43,7 @@ Explanation: without the timestamp patch, nodes will create objects using their
local clock only as a timestamp, so the ordering will be all over the place if
clocks are scrambled.
**Register linear, with timestamp patch**
### Register linear, with timestamp patch
Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 20 --concurrency 20 --workload reg --ops-per-key 100 -I`
@ -54,24 +54,45 @@ Results:
Explanation: S3 objects are not meant to behave like linearizable registers. TODO explain using a counter-example
**Read-after-write CRDT register model**: TODO: determine the expected semantics of such a register, code a checker and show that results are correct
### Read-after-write CRDT register model
**Set, basic test**
TODO: determine the expected semantics of such a register, code a checker and show that results are correct
Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 20 --concurrency 20 --workload set1 --ops-per-key 100`
### Set, basic test (write some items, then read)
Command: `lein run test --nodes-file nodes.vagrant --time-limit 60 --rate 100 --concurrency 100 --workload set1 --ops-per-key 100`
Results:
- ListObjects returns objects not within prefix???? -> BAD, definitely a bug, but maybe it's in the instrumentation code?
- For now, no failures with clock-scramble nemesis + partition nemesis
### Set, continuous test (interspersed reads and writes)
TODO
TODO: nemesis that reconfigures the cluster with a different subset of nodes, to have requests that occur during a resync period.
## Investigating (and fixing) wierd behavior
### Segfaults
They are due to the download being interrupted in the middle (^C during first launch on clean VMs), the `garage` binary is truncated.
Add `:force?` to the `cached-wget!` call in `daemon.clj` to re-download the binary.
### In `jepsen.garage`: prefix wierdness
In `store/garage set1/20231019T163358.615+0200`:
```
INFO [2023-10-19 16:35:20,977] clojure-agent-send-off-pool-207 - jepsen.garage.set list results for prefix set20/ : (set13/0 set13/1 set13/10 set13/11 set13/12 set13/13 set13/14 set13/15 set13/16 set13/17 set13/18 set13/19 set13/2 set13/20 set13/21 set13/22 set13/23 set13/24 set13/25 set13/26 set13/27 set13/28 set13/29 set13/3 set13/30 set13/31 set13/32 set13/33 set13/34 set13/35 set13/36 set13/37 set13/38 set13/39 set13/4 set13/40 set13/41 set13/42 set13/43 set13/44 set13/45 set13/46 set13/47 set13/48 set13/49 set13/5 set13/50 set13/51 set13/52 set13/53 set13/54 set13/55 set13/56 set13/57 set13/58 set13/59 set13/6 set13/60 set13/61 set13/62 set13/63 set13/64 set13/65 set13/66 set13/67 set13/68 set13/69 set13/7 set13/70 set13/71 set13/72 set13/73 set13/74 set13/75 set13/76 set13/77 set13/78 set13/79 set13/8 set13/80 set13/81 set13/82 set13/83 set13/84 set13/85 set13/86 set13/87 set13/88 set13/89 set13/9 set13/90 set13/91 set13/92 set13/93 set13/94 set13/95 set13/96 set13/97 set13/98 set13/99) (node: http://192.168.56.25:3900 )
```
- Sometimes ListObjects returns an empty list???? -> BAD, quorums should ensure this doesn't happen
After inspecting, the actual S3 call made was with prefix "set13/", so at least this is not an error in Garage itself but in the jepsen code.
Finally found out that this was due to closures not correctly capturing their context in the list function in s3api.clj (wtf clojure?)
Not sure exactly where it came from but it seems to have been fixed by making list-inner a separate function and not a sub-function,
and passing all values that were previously in the context (creds and prefix) as additional arguments.
## License

27
script/jepsen.garage/src/jepsen/garage/s3api.clj
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@ -31,19 +31,20 @@
:input-stream bytes-stream
:metadata {:content-length (count some-bytes)}))))
(defn list-inner [creds prefix ct accum]
(let [list-result (s3/list-objects-v2 creds
{:bucket-name (:bucket creds)
:prefix prefix
:continuation-token ct})
new-object-summaries (:object-summaries list-result)
new-objects (map (fn [d] (:key d)) new-object-summaries)
objects (concat new-objects accum)]
(info (:endpoint creds) "ListObjectsV2 prefix(" prefix "), ct(" ct "): " new-objects)
(if (:truncated? list-result)
(list-inner creds prefix (:next-continuation-token list-result) objects)
objects)))
(defn list
"Helper for ListObjects -- just lists everything in the bucket"
[creds prefix]
(defn list-inner [ct accum]
(let [list-result (s3/list-objects-v2 creds
{:bucket-name (:bucket creds)
:prefix prefix
:continuation-token ct})
new-object-summaries (:object-summaries list-result)
new-objects (map (fn [d] (:key d)) new-object-summaries)
objects (concat new-objects accum)]
(info (:endpoint creds) "ListObjectsV2 prefix(" prefix "), ct(" ct "): " new-objects)
(if (:truncated? list-result)
(list-inner (:next-continuation-token list-result) objects)
objects)))
(list-inner nil []))
(info "in s3/list creds:" creds ", prefix:" prefix)
(list-inner creds prefix nil []))

16
script/jepsen.garage/src/jepsen/garage/set.clj
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@ -44,13 +44,15 @@
(util/timeout
10000
(assoc op :type :fail, :error ::timeout)
(let [items (s3/list (:creds this) prefix)]
(info "list results for prefix" prefix ":" items " (node:" (:endpoint (:creds this)) ")")
(let [items-stripped (map (fn [o]
(assert (str/starts-with? o prefix))
(str/replace-first o prefix "")) items)
items-set (set (map parse-long items-stripped))]
(assoc op :type :ok, :value (independent/tuple k items-set))))))))
(do
(info "call s3/list creds: " (:creds this) ", prefix:" prefix)
(let [items (s3/list (:creds this) prefix)]
(info "list results for prefix" prefix ":" items " (node:" (:endpoint (:creds this)) ")")
(let [items-stripped (map (fn [o]
(assert (str/starts-with? o prefix))
(str/replace-first o prefix "")) items)
items-set (set (map parse-long items-stripped))]
(assoc op :type :ok, :value (independent/tuple k items-set)))))))))
(teardown! [this test])
(close! [this test]))