are there any perf tests with Promesa for Clojure?

Interested in how it performs compared to plain Java’s CompletableFuture.

looking at the code, in -bind, there are lookups and writes to ThreadLocal state and the Executor seems to be dynamic Var. Would be interested to see how these effect the perf.

Is there a version of then that would run the code in the same thread? If I have understood the code, it dispatches all the actions into the ForkJoin pool.

some quick server benchmarks (with async postgresql, returning CompletableFuture), with Promesa & calling .thenApply directly:

(defn handler [_]
  (-> (pa/query-one mapper pool ["SELECT id, randomnumber from WORLD where id=$1" (random)])
      (p/then (fn [world]
                {:status 200
                 :headers {"Content-Type" "application/json"}
                 :body (j/write-value-as-bytes world)}))))
; ➜  pohjavirta git:(master) ✗ wrk -t128 -c128 -d10s 
; Running 10s test @ 
;   128 threads and 128 connections
;   Thread Stats   Avg      Stdev     Max   +/- Stdev
;     Latency     3.12ms  541.67us   6.68ms   74.21%
;     Req/Sec   321.14     45.55   620.00     70.40%
;   413172 requests in 10.10s, 62.57MB read
; Requests/sec:  40890.19
; Transfer/sec:      6.19MB

(defn handler [_]
  (-> (pa/query-one mapper pool ["SELECT id, randomnumber from WORLD where id=$1" (random)])
      (.thenApply (reify Function
                    (apply [_ world]
                      {:status 200
                       :headers {"Content-Type" "application/json"}
                       :body (j/write-value-as-bytes world)})))))
; ➜  pohjavirta git:(master) ✗ wrk -t128 -c128 -d10s 
; Running 10s test @ 
;   128 threads and 128 connections
;   Thread Stats   Avg      Stdev     Max   +/- Stdev
;     Latency     2.37ms  347.58us   7.55ms   79.36%
;     Req/Sec   423.41     26.18   820.00     95.55%
;   543764 requests in 10.10s, 82.34MB read
; Requests/sec:  53814.19
; Transfer/sec:      8.15MB

one more with .thenApplyAsync, which also dispatches:

; ➜  pohjavirta git:(master) ✗ wrk -t128 -c128 -d10s 
; Running 10s test @ 
;   128 threads and 128 connections
;   Thread Stats   Avg      Stdev     Max   +/- Stdev
;     Latency     2.55ms    1.45ms  55.75ms   97.50%
;     Req/Sec   405.81     45.27   717.00     82.73%
;   521651 requests in 10.10s, 78.99MB read
; Requests/sec:  51632.87
; Transfer/sec:      7.82MB

51k TPS (Java) vs 41k TPS (Promesa), so some overhead.