Is there an API for tracking the dependencies of a namespace when loaded? That would include anything newly required and already required. I know of tns dependency tracking stuff, but that works on the source level.

Can someone explain to me why r/fold does not run in parallel across all available cores in this example: https://gist.github.com/maacl/953b092af98ee71aa58fbe48f80d6f64

(ns csv2summap.core
  (:require [clojure.data.csv :as csv]
            [ :as io]
            [clojure.core.reducers :as r]))

(with-open [writer (io/writer "numbers.csv")]
  (csv/write-csv
   writer
   (take 1000000 (repeatedly #(vector (char (+ 65 (rand-int 26))) (rand-int 1000))))))

(defn sum-vals
([] {})
([m [k v]]
 (update m k (fnil + 0) (Integer/parseInt v))))

(defn merge-sums
([] {})
([& m] (apply merge-with + m)))

;; r/fold version, should run in parallel on all cores, but does not
(with-open [reader (io/reader "numbers.csv")]
(doall
 (r/fold
  (/ 1000000 12)
  merge-sums
  sum-vals
  (csv/read-csv reader)))) 

is there any problem with maven today? I cannot start my project and yesterday it was working.

error in process sentinel: nrepl-server-sentinel: Could not start nREPL server: Error building classpath. Could not find artifact org.clojure:spec.alpha:jar:0.2.44 in central ()

error in process sentinel: Could not start nREPL server: Error building classpath. Could not find artifact org.clojure:spec.alpha:jar:0.2.44 in central ()

Can someone throw me a hint as to what's wrong with this namespace declaration? According to the error message, spec doesn't like this form, but I see nothing wrong.

Here's the ns form: (ns cql-parser.core (:require [clj-antlr.core :as antlr]))

Here's the error and traceback:

#error {
 :cause Call to clojure.core/ns did not conform to spec.
 :data #:clojure.spec.alpha{:problems [{:path [], :reason Extra input, :pred (clojure.spec.alpha/cat :docstring (clojure.spec.alpha/? clojure.core/string?) :attr-map (clojure.spec.alpha/? clojure.core/map?) :ns-clauses :clojure.core.specs.alpha/ns-clauses), :val ([:require [(quote clj-antlr.core) :as (quote antlr)]]), :via [:clojure.core.specs.alpha/ns-form], :in [1]}], :spec #object[clojure.spec.alpha$regex_spec_impl$reify__2509 0x676cf48 clojure.spec.alpha$regex_spec_impl$reify__2509@676cf48], :value (cql-parser.core [:require [(quote clj-antlr.core) :as (quote antlr)]]), :args (cql-parser.core [:require [(quote clj-antlr.core) :as (quote antlr)]])}
 :via
 [{:type clojure.lang.Compiler$CompilerException
   :message Syntax error macroexpanding clojure.core/ns at (cql_parser/core.clj:1:1).
   :data #:clojure.error{:phase :macro-syntax-check, :line 1, :column 1, :source cql_parser/core.clj, :symbol clojure.core/ns}
   :at [clojure.lang.Compiler checkSpecs Compiler.java 6972]}
  {:type clojure.lang.ExceptionInfo
   :message Call to clojure.core/ns did not conform to spec.
   :data #:clojure.spec.alpha{:problems [{:path [], :reason Extra input, :pred (clojure.spec.alpha/cat :docstring (clojure.spec.alpha/? clojure.core/string?) :attr-map (clojure.spec.alpha/? clojure.core/map?) :ns-clauses :clojure.core.specs.alpha/ns-clauses), :val ([:require [(quote clj-antlr.core) :as (quote antlr)]]), :via [:clojure.core.specs.alpha/ns-form], :in [1]}], :spec #object[clojure.spec.alpha$regex_spec_impl$reify__2509 0x676cf48 clojure.spec.alpha$regex_spec_impl$reify__2509@676cf48], :value (cql-parser.core [:require [(quote clj-antlr.core) :as (quote antlr)]]), :args (cql-parser.core [:require [(quote clj-antlr.core) :as (quote antlr)]])}
   :at [clojure.spec.alpha$macroexpand_check invokeStatic alpha.clj 705]}]
 :trace
 [[clojure.spec.alpha$macroexpand_check invokeStatic alpha.clj 705]
  [clojure.spec.alpha$macroexpand_check invoke alpha.clj 697]
  [clojure.lang.AFn applyToHelper AFn.java 156]
  [clojure.lang.AFn applyTo AFn.java 144]
  [clojure.lang.Var applyTo Var.java 705]
  [clojure.lang.Compiler checkSpecs Compiler.java 6970]
  [clojure.lang.Compiler macroexpand1 Compiler.java 6988]
  [clojure.lang.Compiler macroexpand Compiler.java 7075]
  [clojure.lang.Compiler eval Compiler.java 7161]
  [clojure.lang.Compiler load Compiler.java 7636]
  [clojure.lang.RT loadResourceScript RT.java 381]
  [clojure.lang.RT loadResourceScript RT.java 372]
  [clojure.lang.RT load RT.java 459]
  [clojure.lang.RT load RT.java 424]
  [clojure.core$load$fn__6839 invoke core.clj 6126]
  [clojure.core$load invokeStatic core.clj 6125]
  [clojure.core$load doInvoke core.clj 6109]
  [clojure.lang.RestFn invoke RestFn.java 408]
  [clojure.core$load_one invokeStatic core.clj 5908]
  [clojure.core$load_one invoke core.clj 5903]
  [clojure.core$load_lib$fn__6780 invoke core.clj 5948]
  [clojure.core$load_lib invokeStatic core.clj 5947]
  [clojure.core$load_lib doInvoke core.clj 5928]
  [clojure.lang.RestFn applyTo RestFn.java 142]
  [clojure.core$apply invokeStatic core.clj 667]
  [clojure.core$load_libs invokeStatic core.clj 5985]
  [clojure.core$load_libs doInvoke core.clj 5969]
  [clojure.lang.RestFn applyTo RestFn.java 137]
  [clojure.core$apply invokeStatic core.clj 667]
  [clojure.core$require invokeStatic core.clj 6007]
  [clojure.core$require doInvoke core.clj 6007]
  [clojure.lang.RestFn invoke RestFn.java 408]
  [user$eval150 invokeStatic form-init897609585960091026.clj 1]
  [user$eval150 invoke form-init897609585960091026.clj 1]
  [clojure.lang.Compiler eval Compiler.java 7177]
  [clojure.lang.Compiler eval Compiler.java 7166]
  [clojure.lang.Compiler eval Compiler.java 7166]
  [clojure.lang.Compiler load Compiler.java 7636]
  [clojure.lang.Compiler loadFile Compiler.java 7574]
  [clojure.main$load_script invokeStatic main.clj 475]
  [clojure.main$init_opt invokeStatic main.clj 477]
  [clojure.main$init_opt invoke main.clj 477]
  [clojure.main$initialize invokeStatic main.clj 508]
  [clojure.main$null_opt invokeStatic main.clj 542]
  [clojure.main$null_opt invoke main.clj 539]
  [clojure.main$main invokeStatic main.clj 664]
  [clojure.main$main doInvoke main.clj 616]
  [clojure.lang.RestFn applyTo RestFn.java 137]
  [clojure.lang.Var applyTo Var.java 705]
  [clojure.main main main.java 40]]}
Error loading lighttable.nrepl.handler: Syntax error macroexpanding clojure.core/ns at (cljs/source_map/base64_vlq.clj:1:1).
Syntax error compiling var at (C:\Users\Frank Adrian\AppData\Local\Temp\form-init897609585960091026.clj:1:4762).
Unable to resolve var: lighttable.nrepl.handler/lighttable-ops in this context

"We can't fully display this message" above

anyway, this makes me think you had ' in your require > (cql-parser.core [:require [(quote clj-antlr.core) :as (quote antlr)]]), :args (cql-parser.core [:require [(quote clj-antlr.core) :as (quote antlr)]])

I'm making a program to help me learn low level programming, and prototype low level algorithms. Is this a reasonable way to provide a lazy-seq view onto the successive states of an atom? Is there something safer? I'm afraid of what happens if a watch is set and nobody accesses the lazy-seq, wondering how best to handle this. It almost looks like a core.async backpressure problem.

(defn ->region
  "Uses an atom to help implement fake mutation on top of immutable data.
  See also change-list."
  [N]
  (atom
   (apply vector-of :byte
          (repeat N 0))))

(defprotocol ChangeWatcher
  (register [this]
    "Should return something that offers access to the changes.")
  (unregister [this]
    "Should turn off the supply of data."))

(defn change-list
  "Given a pile of bytes allocated in an atom by ->region, creates a lazy-seq
  of the values that pile takes on over time."
  [region]
  (let [marker (UUID/randomUUID)
        data-funnel (ArrayBlockingQueue. 4096) ; puts will block after this
        watcher (fn watcher
                  [_k _r old-state new-state]
                  (.put data-funnel new-state))]
    (reify ChangeWatcher
      (register [this]
        (add-watch region marker watcher)
        (repeatedly #(.take data-funnel)))
      (unregister [this]
        (remove-watch region marker)))))

I think the api of core.cache is inherently racy. still working through it but it seems like it can't work on atoms

Does compile expand macros? I'm trying to configure routes for a web app based on the files available at the start time. The problem is that app should be able to work both if run from src and if run from an uberjar. And listing files in jars is not a simple task.

Hey all, I have a bit of a weird issue at the moment. I have a Ring webserver which serves HTML. When I run it in development on my laptop, every now and then after rendering a page, the java instance will start spinning at 100% CPU and never stop. The application doesn't stop either, you can still call ring handlers. The weird thing is that I can only reproduce it on my laptop in development (lein repl). I can't reproduce it on my desktop, I can't reproduce it on my laptop with an uberjar. Both laptop and desktop use the same java / clojure version. I've tried removing things from my handler, but I can't pinpoint where the issue is exactly. Does anyone have any tips on debugging a problem like this?

@kevin.van.rooijen You should be able to generate stack traces from the process (maybe with kill -3 <pid> or jstack if you have it) and see what they are doing when you see 100% CPU.

Thanks for the suggestion, I'll try that out. jstack sounds like what I need

I would probably also try starting the app from a plain clj REPL, to rule out any lein weirdness, or any other dev/editor stuff.

Yeah I'll try plain clj. The weird thing is that I can only reproduce this issue specifically on my laptop with lein run. Which is very frustrating

Do you have any Ring middleware specific to dev? ring-reload etc? Could be something in your plugins/middleware...

Not really anything specific to dev, and I'm not using auto reloading. I did add gzip middleware recently, but I tried disabling that and it didn't change anything

Ok well. Can't seem to reproduce it anymore :man-shrugging: Been bumping my head against this for at least 2 hours

Maybe there was just something wrong with my local setup. If it happens again I'll be sure to try jstack, thanks for the tip!

Heisenbug 🐛

How do you count optimum CPU / memory for clojure app in docker container? Do you use some tools for stress test like for example 80 request at the same time? How to measure the right CPU / memory limits for app in cloud? Do you do desktop stress tests or jump right to cloud tests, because tests on localhosts gives different results (this is what I expect). Do you use tools or set some random values and modify them manually in time? The topic seems to be very hard and without only one answer. Summary up: 1. Do we have good tools in Clojure for stress tests like 80 requests at the same time? (I would like to use Clojure to generate requests) 2. How to predict CPU / memory limitation for clojure app?

Do I need to provide further information regarding my question above or is everybody just as mystified as me? 🙂

Are there any gotchyas to be aware of when writing a call to prepl? I'm playing with it at the moment, passing it a line numbering pushback reader which wraps a piped reader connected to a piped writer which I'm writing strings to, it seems to read off the reader, but the output method (which just logs the value it gets) is never being called. I'm flushing the writer, but do I have to do something special, like write an EOF when I want to push it? At the moment I'm writing newlines whenever I want to finish a segment to send.