Im averaging 20 miliseconds per 1000 get requests + response + parse and check
on parsed value.

can i improve this?

import asyncdispatch, httpclient, json, strutils, times

var found = false
var checked = 0

const
  CONCURRENCY = 200
  BATCH = 1000



type AsyncSemaphore = ref object
  count: int
  waiters: seq[Future[void]]

proc newAsyncSemaphore(n: int): AsyncSemaphore =
  AsyncSemaphore(count: n, waiters: @[])



proc acquire(s: AsyncSemaphore): Future[void] =
  if s.count > 0:
    dec s.count
    result = newFuture[void]("sem.acquire")
    result.complete()
  else:
    result = newFuture[void]("sem.acquire")
    s.waiters.add(result)

proc release(s: AsyncSemaphore) =
  if s.waiters.len > 0:
    let waiter = s.waiters[0]
    s.waiters.delete(0)
    waiter.complete()
  else:
    inc s.count

var sem = newAsyncSemaphore(CONCURRENCY)

proc checkID(id: int): Future[void] {.async.} =
  await sem.acquire()
  let client = newAsyncHttpClient()
  client.headers = newHttpHeaders({
    "Cookie": "JSESSIONID=cookiehere",
    "X-Requested-With": "XMLHttpRequest",
    "Accept": "/"
  })
  try:
    let url = "urlhere" & $id
    let response = await client.get(url)
    let body = parseJson(await response.body)
    if body.hasKey("lessonCompleted") and body["lessonCompleted"].getBool():
      echo "[+] Found: ", id
      found = true
  except:
    discard
  finally:
    client.close()
    sem.release()
    inc checked

proc main() {.async.} =
  echo "Starting with concurrency=", CONCURRENCY
  echo "Starting with batch=", BATCH
  var id = 0

  while not found:
    let start = cpuTime()
    var futures: seq[Future[void]]

    for i in 0..<BATCH:
      futures.add(checkID(id + i))

    await all(futures)
    let elapsed = cpuTime() - start
    id += BATCH
    echo "[" & $elapsed.formatFloat(ffDecimal, 2) & "]: ", id

waitFor main()
echo "Done. Total checked: ", checked