Feature: handle seq[byte] and strings using openArray's and memory retention (#7)

Limited support for passing seq's of bytes and strings to tasklets using openArray

apatheia.nimble

@@ -13,3 +13,4 @@ requires "threading"
 requires "taskpools >= 0.0.5"
 requires "chronicles"
 
+include "build.nims"

build.nims

@@ -0,0 +1,8 @@
+
+import std/[os, strutils]
+
+task test, "unit tests":
+  for file in listFiles("tests"):
+    let name = file.splitPath().tail
+    if name.startsWith("t") and name.endsWith(".nim"):
+      exec "nim c -r " & file

config.nims

@@ -1,2 +1,4 @@
 
 --threads:on
+
+include "build.nims"

src/apatheia.nim

@@ -1,3 +1,2 @@
-
 import apatheia/tasks
 export tasks

src/apatheia/jobs.nim

@@ -2,6 +2,7 @@ import std/tables
 import std/macros
 
 import ./queues
+import ./memretainers
 
 import taskpools
 import chronos
@@ -16,75 +17,172 @@ logScope:
 
 ## This module provides a simple way to submit jobs to taskpools
 ## and getting a result returned via an async future.
-## 
+##
+## Any compatible arguments of `seq[T]` or `string` args passed
+## via the `submit` macro will be converted into the special `OpenArrayHolder[T]` type.
+## The `submit` macro converts these arguments in this object and retains the 
+## memory associated with the original `seq[T]` or `string` object.
+## This greatly simplifies the passing of these these types in `refc`.
+##
+## Note, for `arc` or `orc` GC's this setup will be replaced with a move operation in the future.
+## These GC's also allow greater support for moving GC types across thread boundaries.
+##
+## Currently this module limits support for GC types to ensure `refc` safety.
 ##
 
 type
-  JobId* = uint ## job id, should match `future.id()`
-
-  JobQueue*[T] = ref object
-    ## job queue object
+  JobQueue*[T] = ref object ## job queue object
     queue*: SignalQueue[(JobId, T)]
     futures*: Table[JobId, Future[T]]
     taskpool*: Taskpool
     running*: bool
 
-  JobResult*[T] = object
-    ## hold a job result to be returned by jobs
+  JobResult*[T] = object ## hold the result of a job after it finishes
     id*: JobId
     queue*: SignalQueue[(JobId, T)]
 
+  OpenArrayHolder*[T] = object
+    data*: ptr UncheckedArray[T]
+    size*: int
+
+  SupportedSeqTypes* = byte | SomeInteger | SomeFloat
+
+template toOpenArray*[T](arr: OpenArrayHolder[T]): auto =
+  system.toOpenArray(arr.data, 0, arr.size)
+
+func jobId*[T](fut: Future[T]): JobId =
+  JobId fut.id()
+
 proc processJobs*[T](jobs: JobQueue[T]) {.async.} =
   ## Starts a "detached" async processor for a given job queue.
   ## 
   ## This processor waits for events from the queue in the JobQueue
-  ## and complete the associated futures.
+  ## and completes the associated future.
 
   const tn: string = $(JobQueue[T])
-  info "Processing jobs in job queue for type ", type=tn
+  info "Processing jobs in job queue for type ", type = tn
   while jobs.running:
-    let res = await(jobs.queue.wait()).get()
-    trace "got job result", jobResult = $res
-    let (id, ret) = res
-    var fut: Future[T]
-    if jobs.futures.pop(id, fut):
-      fut.complete(ret)
+    let (id, ret) = await(jobs.queue.wait()).get()
+    trace "got job result", jobId = id
+    releaseMemory(id) # always release any retained memory
+    if (var fut: Future[T]; jobs.futures.pop(id, fut)):
+      if not fut.finished():
+        fut.complete(ret)
     else:
       raise newException(IndexDefect, "missing future: " & $id)
-  info "Finishing processing jobs for type ", type=tn
+  info "Finishing processing jobs for type ", type = tn
 
 proc createFuture*[T](jobs: JobQueue[T], name: static string): (JobResult[T], Future[T]) =
   ## Creates a future that returns the result of the associated job.
   let fut = newFuture[T](name)
-  let id = JobId fut.id()
+  let id = fut.jobId()
   jobs.futures[id] = fut
-  trace "jobs added: ", numberJobs = jobs.futures.len()
-  return (JobResult[T](id: id, queue: jobs.queue), fut, )
+  trace "job added: ", numberJobs = jobs.futures.len()
+  return (JobResult[T](id: id, queue: jobs.queue), fut)
 
-proc newJobQueue*[T](maxItems: int = 0, taskpool: Taskpool = Taskpool.new()): JobQueue[T] {.raises: [ApatheiaSignalErr].} =
+proc newJobQueue*[T](
+    maxItems: int = 0, taskpool: Taskpool = Taskpool.new()
+): JobQueue[T] {.raises: [ApatheiaSignalErr].} =
   ## Creates a new async-compatible threaded job queue.
-  result = JobQueue[T](queue: newSignalQueue[(uint, T)](maxItems), taskpool: taskpool, running: true)
+  result = JobQueue[T](
+    queue: newSignalQueue[(uint, T)](maxItems), taskpool: taskpool, running: true
+  )
   asyncSpawn(processJobs(result))
 
+template checkJobArgs*[T](exp: seq[T], fut: untyped): OpenArrayHolder[T] =
+  when T is SupportedSeqTypes:
+    let rval = SeqRetainer[T](data: exp)
+    retainMemory(fut.jobId(), rval)
+    let expPtr = OpenArrayHolder[T](
+      data: cast[ptr UncheckedArray[T]](unsafeAddr(rval.data[0])), size: rval.data.len()
+    )
+    expPtr
+  else:
+    {.error: "unsupported sequence type for job argument: " & $typeof(seq[T]).}
+
+template checkJobArgs*(exp: string, fut: untyped): OpenArrayHolder[char] =
+    let rval = StrRetainer(data: exp)
+    retainMemory(fut.jobId(), rval)
+    let expPtr = OpenArrayHolder[char](
+      data: cast[ptr UncheckedArray[char]](unsafeAddr(rval.data[0])), size: rval.data.len()
+    )
+    expPtr
+
+template checkJobArgs*(exp: typed, fut: untyped): auto =
+  exp
+
 macro submitMacro(tp: untyped, jobs: untyped, exp: untyped): untyped =
   ## modifies the call expression to include the job queue and 
   ## the job id parameters
 
-  let jobRes = genSym(nskLet, "jobRes")
-  let futName = genSym(nskLet, "fut")
+  let jobRes = ident("jobRes")
+  let futName = ident("fut")
   let nm = newLit(repr(exp))
+
+  var argids = newSeq[NimNode]()
+  var letargs = nnkLetSection.newTree()
+  for i, p in exp[1 ..^ 1]:
+    let id = ident "arg" & $i
+    argids.add(id)
+    let pn = nnkCall.newTree(ident"checkJobArgs", p, `futName`)
+    letargs.add nnkIdentDefs.newTree(id, newEmptyNode(), pn)
+
   var fncall = nnkCall.newTree(exp[0])
   fncall.add(jobRes)
-  for p in exp[1..^1]: fncall.add(p)
+  for p in argids:
+    fncall.add(p)
 
-  result = quote do:
-    let (`jobRes`, `futName`) = createFuture(`jobs`, `nm`)
-    `jobs`.taskpool.spawn(`fncall`)
-    `futName`
+  result = quote:
+    block:
+      let (`jobRes`, `futName`) = createFuture(`jobs`, `nm`)
+      `letargs`
+      when typeof(`fncall`) isnot void:
+        {.
+          error:
+            "Apatheia jobs cannot return values. The given proc returns type: " &
+            $(typeof(`fncall`)) & " for call " & astToStr(`fncall`)
+        .}
+      `jobs`.taskpool.spawn(`fncall`)
+      `futName`
 
-  # echo "submit: res:\n", result.repr
-  # echo ""
+  when isMainModule:
+    echo "\nSUBMIT MACRO::\n", result.repr
+    echo ""
 
 template submit*[T](jobs: JobQueue[T], exp: untyped): Future[T] =
   submitMacro(T, jobs, exp)
 
+when isMainModule:
+  import os
+  import chronos/threadsync
+  import chronos/unittest2/asynctests
+
+  proc addNumValues(
+      jobResult: JobResult[float], base: float, vals: OpenArrayHolder[float]
+  ) =
+    os.sleep(100)
+    var res = base
+    for x in vals.toOpenArray():
+      res += x
+    discard jobResult.queue.send((jobResult.id, res))
+
+  proc addStrings(jobResult: JobResult[float], vals: OpenArrayHolder[string]) =
+    discard
+
+  suite "async tests":
+    var tp = Taskpool.new(num_threads = 2) # Default to the number of hardware threads.
+
+    asyncTest "basic openarray":
+      var jobs = newJobQueue[float](taskpool = tp)
+
+      let job = jobs.submit(addNumValues(10.0, @[1.0.float, 2.0]))
+      let res = await job
+
+      check res == 13.0
+
+    asyncTest "don't compile":
+      check not compiles(
+        block:
+          var jobs = newJobQueue[float](taskpool = tp)
+          let job = jobs.submit(addStrings(@["a", "b", "c"]))
+      )

src/apatheia/macroutils.nim

@@ -3,22 +3,19 @@ import std/[tables, strutils, typetraits, macros]
 proc makeProcName*(s: string): string =
   result = ""
   for c in s:
-    if c.isAlphaNumeric: result.add c
+    if c.isAlphaNumeric:
+      result.add c
 
 proc hasReturnType*(params: NimNode): bool =
-  if params != nil and params.len > 0 and params[0] != nil and
-     params[0].kind != nnkEmpty:
+  if params != nil and params.len > 0 and params[0] != nil and params[0].kind != nnkEmpty:
     result = true
 
 proc getReturnType*(params: NimNode): NimNode =
-  if params != nil and params.len > 0 and params[0] != nil and
-     params[0].kind != nnkEmpty:
+  if params != nil and params.len > 0 and params[0] != nil and params[0].kind != nnkEmpty:
     result = params[0]
 
 proc firstArgument*(params: NimNode): (NimNode, NimNode) =
-  if params != nil and
-      params.len > 0 and
-      params[1] != nil and
+  if params != nil and params.len > 0 and params[1] != nil and
       params[1].kind == nnkIdentDefs:
     result = (ident params[1][0].strVal, params[1][1])
   else:
@@ -29,15 +26,13 @@ iterator paramsIter*(params: NimNode): tuple[name, ntype: NimNode] =
   for i in 1 ..< params.len:
     let arg = params[i]
     let argType = arg[^2]
-    for j in 0 ..< arg.len-2:
+    for j in 0 ..< arg.len - 2:
       yield (arg[j], argType)
 
 proc signalTuple*(sig: NimNode): NimNode =
   let otp = nnkEmpty.newTree()
   # echo "signalObjRaw:sig1: ", sig.treeRepr
-  let sigTyp =
-    if sig.kind == nnkSym: sig.getTypeInst
-    else: sig.getTypeInst
+  let sigTyp = if sig.kind == nnkSym: sig.getTypeInst else: sig.getTypeInst
   # echo "signalObjRaw:sig2: ", sigTyp.treeRepr
   let stp =
     if sigTyp.kind == nnkProcTy:
@@ -52,14 +47,16 @@ proc signalTuple*(sig: NimNode): NimNode =
   # echo "signalObjRaw:sig: ", stp.repr
 
   var args: seq[NimNode]
-  for i in 2..<stp.len:
+  for i in 2 ..< stp.len:
     args.add stp[i]
 
   result = nnkTupleConstr.newTree()
   if isGeneric:
-    template genArgs(n): auto = n[1][1]
+    template genArgs(n): auto =
+      n[1][1]
+
     var genKinds: Table[string, NimNode]
-    for i in 1..<stp.genArgs.len:
+    for i in 1 ..< stp.genArgs.len:
       genKinds[repr stp.genArgs[i]] = otp[i]
     for arg in args:
       result.add genKinds[arg[1].repr]
@@ -72,19 +69,20 @@ proc signalTuple*(sig: NimNode): NimNode =
   # echo ""
   if result.len == 0:
     # result = bindSym"void"
-    result = quote do:
+    result = quote:
       tuple[]
 
 proc mkParamsVars*(paramsIdent, paramsType, params: NimNode): NimNode =
   ## Create local variables for each parameter in the actual RPC call proc
-  if params.isNil: return
+  if params.isNil:
+    return
 
   result = newStmtList()
   var varList = newSeq[NimNode]()
   var cnt = 0
   for paramid, paramType in paramsIter(params):
     let idx = newIntLitNode(cnt)
-    let vars = quote do:
+    let vars = quote:
       var `paramid`: `paramType` = `paramsIdent`[`idx`]
     varList.add vars
     cnt.inc()
@@ -106,9 +104,10 @@ proc mkParamsType*(paramsIdent, paramsType, params, genericParams: NimNode): Nim
   ##   
   ##   proc multiplyrpc(params: RpcType_multiplyrpc): int = 
   ## 
-  if params.isNil: return
+  if params.isNil:
+    return
 
-  var tup = quote do:
+  var tup = quote:
     type `paramsType` = tuple[]
   for paramIdent, paramType in paramsIter(params):
     # processing multiple variables of one type
@@ -129,7 +128,8 @@ proc procIdentAppend*(id: NimNode, name: string): NimNode =
 
 proc mkCall*(callName, params: NimNode): NimNode =
   ## Create local variables for each parameter in the actual RPC call proc
-  if params.isNil: return
+  if params.isNil:
+    return
   var argList = newSeq[NimNode]()
   for paramId, paramType in paramsIter(params):
     argList.add paramId
@@ -138,9 +138,10 @@ proc mkCall*(callName, params: NimNode): NimNode =
 
 proc mkProc*(name, params, body: NimNode): NimNode =
   let args = params.copyNimTree()
-  result = quote do:
+  result = quote:
     proc `name`() {.nimcall.} =
       `body`
+
   result[3].del(0)
   for arg in args:
     result.params.add arg

src/apatheia/memretainers.nim

@@ -0,0 +1,30 @@
+import std/tables
+
+import ./types
+export types
+
+type
+  Retainer* = ref object of RootObj
+
+  SeqRetainer*[T] = ref object of Retainer
+    data*: seq[T]
+
+  StrRetainer* = ref object of Retainer
+    data*: string
+
+var memoryRetainerTable = newTable[uint, seq[Retainer]]()
+
+proc retainMemory*(id: JobId, mem: Retainer) {.gcsafe, raises: [].} =
+  {.cast(gcsafe).}:
+    memoryRetainerTable[].withValue(id, value):
+      value[].add(mem)
+    do:
+      memoryRetainerTable[id] = @[mem]
+
+proc releaseMemory*(id: JobId) {.gcsafe, raises: [].} =
+  {.cast(gcsafe).}:
+    memoryRetainerTable.del(id)
+
+proc retainedMemoryCount*(): int {.gcsafe, raises: [].} =
+  {.cast(gcsafe).}:
+    memoryRetainerTable.len()

src/apatheia/queues.nim

@@ -10,23 +10,23 @@ export options
 export threadsync
 export chronos
 
-type
-  ChanPtr[T] = ptr Channel[T]
+type ChanPtr[T] = ptr Channel[T]
 
 proc allocSharedChannel[T](): ChanPtr[T] =
   cast[ChanPtr[T]](allocShared0(sizeof(Channel[T])))
 
-type
-  SignalQueue*[T] = object
-    signal: ThreadSignalPtr
-    chan*: ChanPtr[T]
+type SignalQueue*[T] = object
+  signal: ThreadSignalPtr
+  chan*: ChanPtr[T]
 
 proc dispose*[T](val: SignalQueue[T]) =
   ## Call to properly dispose of a SignalQueue.
   deallocShared(val.chan)
   discard val.signal.close()
 
-proc newSignalQueue*[T](maxItems: int = 0): SignalQueue[T] {.raises: [ApatheiaSignalErr].} =
+proc newSignalQueue*[T](
+    maxItems: int = 0
+): SignalQueue[T] {.raises: [ApatheiaSignalErr].} =
   ## Create a signal queue compatible with Chronos async.
   let res = ThreadSignalPtr.new()
   if res.isErr():

src/apatheia/tasks.nim

@@ -1,4 +1,3 @@
-
 import std/[macros, strutils]
 
 import macroutils
@@ -6,14 +5,38 @@ import macroutils
 import jobs
 export jobs
 
-# TODO: make these do something useful or remove them
+## Tasks provide a convenience wrapper for using the jobs module. It also
+## provides some extra conveniences like handling a subset of `openArray[T]`
+## types in a safe manner using `OpenArrayHolder[T]` type.
+## 
+## The `asyncTask` macro works by creating a wrapper proc around the 
+## annotated user proc. The transformation looks similar to:
+## 
+## .. code-block::
+##      proc doHashes*(data: openArray[byte], opts: HashOptions): float {.asyncTask.} =
+##        result = 10.0
+##
+## 
+## .. code-block::
+##     proc doHashesTasklet*(data: openArray[byte]; opts: HashOptions): float {.nimcall.} =
+##        result = 10.0
+##     
+##     proc doHashes*(jobResult: JobResult[float]; data: OpenArrayHolder[byte];
+##                    opts: HashOptions) {.nimcall.} =
+##       let val {.inject.} = doHashesTasklet(convertParamType(data),
+##                                            convertParamType(opts))
+##       discard jobResult.queue.send((jobResult.id, val))
+## 
+## Paramters with type of `openArray[T]` have special support and are converted
+## into the `OpenArrayHolder[T]` type from the jobs module. See the jobs module
+## for more information.
+## 
+template convertParamType*[T](obj: OpenArrayHolder[T]): auto =
+  static:
+    echo "CONVERTPARAMTYPE:: ", $typeof(obj)
+  obj.toOpenArray()
 
-template checkParamType*(obj: object): auto =
-  # for name, field in obj.fieldPairs():
-  #   echo "field name: ", name
-  obj
-
-template checkParamType*(obj: typed): auto =
+template convertParamType*(obj: typed): auto =
   obj
 
 macro asyncTask*(p: untyped): untyped =
@@ -30,33 +53,43 @@ macro asyncTask*(p: untyped): untyped =
     # pragmas = p[4]
     body = p[6]
     name = repr(procId).strip(false, true, {'*'})
-  
+
   if not hasReturnType(params):
     error("tasklet definition must have return type", p)
 
   # setup inner tasklet proc
-  let tp = mkProc(procId.procIdentAppend("Tasklet"),
-                  params, body)
+  let tp = mkProc(procId.procIdentAppend("Tasklet"), params, body)
 
   # setup async wrapper code
   var asyncBody = newStmtList()
   let tcall = newCall(ident(name & "Tasklet"))
   for paramId, paramType in paramsIter(params):
-    tcall.add newCall("checkParamType", paramId)
-  asyncBody = quote do:
+    tcall.add newCall("convertParamType", paramId)
+  asyncBody = quote:
     let val {.inject.} = `tcall`
-    discard jobResult.queue.send((jobResult.id, val,))
+    discard jobResult.queue.send((jobResult.id, val))
+
+  let retType =
+    if not hasReturnType(params):
+      ident"void"
+    else:
+      params.getReturnType()
 
-  var asyncParams = params.copyNimTree()
-  let retType = if not hasReturnType(params): ident"void"
-                else: params.getReturnType()
   let jobArg = nnkIdentDefs.newTree(
-    ident"jobResult",
-    nnkBracketExpr.newTree(ident"JobResult", retType),
-    newEmptyNode()
+    ident"jobResult", nnkBracketExpr.newTree(ident"JobResult", retType), newEmptyNode()
   )
-  asyncParams[0] = newEmptyNode()
-  asyncParams.insert(1, jobArg)
+  var asyncParams = nnkFormalParams.newTree()
+  asyncParams.add newEmptyNode()
+  asyncParams.add jobArg
+  for i, p in params[1 ..^ 1]:
+    let pt = p[1]
+    if pt.kind == nnkBracketExpr and pt[0].repr == "openArray":
+      # special case openArray to support special OpenArrayHolder from jobs module
+      p[1] = nnkBracketExpr.newTree(ident"OpenArrayHolder", pt[1])
+      asyncParams.add p
+    else:
+      asyncParams.add p
+
   let fn = mkProc(procId, asyncParams, asyncBody)
 
   result = newStmtList()
@@ -67,13 +100,9 @@ macro asyncTask*(p: untyped): untyped =
     echo "asyncTask:body:\n", result.repr
 
 when isMainModule:
+  type HashOptions* = object
+    striped*: bool
 
-  type
-    HashOptions* = object
-      striped*: bool
-
-  proc doHashes2*(data: openArray[byte],
-                  opts: HashOptions): float {.asyncTask.} =
+  proc doHashes*(data: openArray[byte], opts: HashOptions): float {.asyncTask.} =
     echo "hashing"
-
-
+    result = 10.0

src/apatheia/types.nim

@@ -1,4 +1,5 @@
-
 type
   ApatheiaException* = object of CatchableError
   ApatheiaSignalErr* = object of ApatheiaException
+
+  JobId* = uint ## job id, should match `future.id()`

tests/tjobs.nim

@@ -8,6 +8,7 @@ import taskpools
 
 import apatheia/queues
 import apatheia/jobs
+import apatheia/memretainers
 
 proc addNumsRaw(a, b: float): float =
   os.sleep(50)
@@ -17,10 +18,29 @@ proc addNums(jobResult: JobResult[float], a, b: float) =
   let res = addNumsRaw(a, b)
   discard jobResult.queue.send((jobResult.id, res,))
 
+proc addNumsIncorrect(jobResult: JobResult[float], vals: openArray[float]): float =
+  discard
+
+proc addNumValues(jobResult: JobResult[float], base: float, vals: OpenArrayHolder[float]) =
+  os.sleep(100)
+  var res = base
+  for x in vals.toOpenArray():
+    res += x
+  discard jobResult.queue.send((jobResult.id, res,))
+
+proc strCompute(jobResult: JobResult[int], vals: OpenArrayHolder[char]) =
+  discard jobResult.queue.send((jobResult.id, vals.size,))
+
+proc addStrings(jobResult: JobResult[float], vals: OpenArrayHolder[string]) =
+  discard
+
 suite "async tests":
 
   var tp = Taskpool.new(num_threads = 2) # Default to the number of hardware threads.
 
+  asyncTest "cannot return value":
+    check not compiles(await jobs.submit(addNums(1.0, 2.0,)))
+
   asyncTest "test":
     var jobs = newJobQueue[float](taskpool = tp)
 
@@ -28,3 +48,30 @@ suite "async tests":
 
     check res == 3.0
 
+  asyncTest "testing seq":
+    var jobs = newJobQueue[float](taskpool = tp)
+    let res = await jobs.submit(addNumValues(10.0, @[1.0.float, 2.0]))
+    check res == 13.0
+
+  asyncTest "testing string":
+    var jobs = newJobQueue[int](taskpool = tp)
+    let res = await jobs.submit(strCompute("hello world!"))
+    check res == 12
+
+  asyncTest "testing arrays":
+    var jobs = newJobQueue[float](taskpool = tp)
+    let fut1 = jobs.submit(addNumValues(10.0, @[1.0.float, 2.0]))
+    let fut2 = jobs.submit(addNumValues(20.0, @[3.0.float, 4.0]))
+    check retainedMemoryCount() == 2
+    let res1 = await fut1
+    let res2 = await fut2
+    check res1 == 13.0
+    check res2 == 27.0
+    check retainedMemoryCount() == 0
+
+  asyncTest "don't compile":
+    check not compiles(
+      block:
+        var jobs = newJobQueue[float](taskpool = tp)
+        let job = jobs.submit(addStrings(@["a", "b", "c"]))
+    )

tests/ttasks.nim

@@ -6,6 +6,7 @@ import chronos/unittest2/asynctests
 import taskpools
 
 import apatheia/tasks
+import apatheia/memretainers
 
 proc addNums(a, b: float): float {.asyncTask.} =
   os.sleep(50)
@@ -17,6 +18,11 @@ proc addNumValues(vals: openArray[float]): float {.asyncTask.} =
   for x in vals:
     result += x
 
+proc strCompute(val: openArray[char]): int {.asyncTask.} =
+  ## note includes null terminator!
+  return val.len()
+
+
 suite "async tests":
   var tp = Taskpool.new(num_threads = 2) # Default to the number of hardware threads.
   var jobsVar = newJobQueue[float](taskpool = tp)
@@ -35,3 +41,19 @@ suite "async tests":
     let args = @[1.0, 2.0, 3.0]
     let res = await jobs.submit(addNumValues(args))
     check res == 6.0
+
+  asyncTest "test strCompute":
+    var jobs = newJobQueue[int](taskpool = tp)
+    let res = await jobs.submit(strCompute("hello world!"))
+    check res == 13 # note includes cstring null terminator
+
+  asyncTest "testing openArrays":
+    var jobs = newJobQueue[float](taskpool = tp)
+    let fut1 = jobs.submit(addNumValues(@[1.0.float, 2.0]))
+    let fut2 = jobs.submit(addNumValues(@[3.0.float, 4.0]))
+    check retainedMemoryCount() == 2
+    let res1 = await fut1
+    let res2 = await fut2
+    check res1 == 3.0
+    check res2 == 7.0
+    check retainedMemoryCount() == 0