Error: Can not attach to current VM

[vkurup]

Hi, I'm guessing I'm doing something wrong, but I haven't figured out what yet. I'm trying to run through the first steps of the tutorial on a M3 Macbook Pro, but I get the Can not attach to current VM error. I've followed all of the steps in the tutorial:

~/dev/profiling-tutorial $ uname -v
Darwin Kernel Version 23.5.0: Wed May  1 20:17:33 PDT 2024; root:xnu-10063.121.3~5/RELEASE_ARM64_T6031

~/dev/profiling-tutorial $ java -version
openjdk version "17.0.10" 2024-01-16
OpenJDK Runtime Environment Temurin-17.0.10+7 (build 17.0.10+7)
OpenJDK 64-Bit Server VM Temurin-17.0.10+7 (build 17.0.10+7, mixed mode)

~/dev/profiling-tutorial $ cat deps.edn
{:paths ["src"]
 :deps {com.clojure-goes-fast/clj-async-profiler {:mvn/version "1.2.0"}}}

~/dev/profiling-tutorial $ clj -J-Djdk.attach.allowAttachSelf
[Rebel readline] Type :repl/help for online help info
user=> (require 'tutorial.binary-trees)
nil
user=> (require '[clj-async-profiler.core :as prof])
nil
user=> (prof/profile (tutorial.binary-trees/main 20))
Execution error (IOException) at sun.tools.attach.HotSpotVirtualMachine/<init> (HotSpotVirtualMachine.java:76).
Can not attach to current VM
user=>

[alexander-yakushev]

Hi, this error usually happens when jdk.attach.allowAttachSelf is not enabled, but you are definitely trying to enable it. Please check if (System/getProperty "jdk.attach.allowAttachSelf") in the REPL returns "" (an empty string) for you.

[vkurup]

Hmm, it actually returns nil:

user=> (System/getProperty "jdk.attach.allowAttachSelf")
nil

I also tried to set it via setProperty in the REPL (to "1" and "true") but neither attempt seemed to get the profiler to attach.

[alexander-yakushev]

Yeah, chaging it at runtime wouldn't help. Try doing it like this:

;; deps.edn
{:paths ["src"]
 :deps {com.clojure-goes-fast/clj-async-profiler {:mvn/version "1.2.0"}}
 :aliases {:attach {:jvm-opts ["-Djdk.attach.allowAttachSelf"]}}
}

Then clj -A:attach and then so on.

Could it be by chance that your clj binary is some sort of alias/wrapper that doesn't pass all the arguments down?

[vkurup]

Ahh, that was it! I'm not sure what my clj binary is doing, but switching to the clojure binary fixes my issue. Thanks for the help debugging my setup!

[alexander-yakushev]

No probs, that was a tricky one.