Is it a Virus?
✔ NO - Safe
Must be in C:\\Program Files\\Clojure\\clojure.exe
Warning
Multiple JVMs normal during builds or REPL sessions
clojure.exe typically launches or spawns JVMs per session or tool
Can I Disable?
<strong>YES</strong>
Close active CLJ sessions and disable any startup tasks that launch clojure.exe
What is clojure.exe?
clojure.exe is the Windows launcher used to run Clojure programs by starting a Java Virtual Machine (JVM) instance and loading your CLJ/CLJS code. It acts as a bridge between native Windows processes and the JVM-based runtime, enabling scripts, REPLs, and build tools to execute within a managed environment.
This launcher delegates work to the JVM, loading the Clojure runtime and your project code. It coordinates with tools like Leiningen or deps.edn, and may spawn one or more JVM processes per REPL, test, or build task to isolate work and improve stability.
Quick Fact: The clojure.exe launcher promotes JVM-based isolation, letting multiple Clojure tasks co-exist without corrupting each other.
Types of Clojure Processes
- Launcher Process: clojure.exe itself coordinates startup and basic I/O for Clojure runs (1 instance)
- JVM Process: Runs the Clojure runtime and your code (one or more per REPL, script, or build task)
- Build Tool Process: Leiningen/Boot/Deps.edn tasks may spawn dedicated JVMs during builds
- Compiler/Reader Process: Clojure compiler and reader components engaged during compilation
- Tooling/IDE Process: nREPL servers or IDE integrations connect to clojure.exe for evaluation
- Background/Utility Process: Background watchers, hot-reload tasks, or file-change scanners
Is clojure.exe Safe?
Yes, clojure.exe is safe when downloaded from official sources and used to launch legitimate Clojure programs.
Is clojure.exe a Virus or Malware?
The real clojure.exe is not a virus. However, malware may masquerade as a clojure.exe to mislead users.
How to Tell if clojure.exe is Legitimate or Malware
- File Location: Must be in C:\\Program Files\\Clojure\\clojure.exe or C:\\Program Files (x86)\\Clojure\\clojure.exe. Any other location is suspicious.
- Digital Signature: Right-click clojure.exe -> Properties -> Digital Signatures. Signature should verify against the official Clojure project signer.
- Resource Usage: Normal usage is 1-15% CPU and 50-200 MB memory per active JVM. Constant high usage when idle is suspicious.
- Behavior: clojure.exe should run only when you start a Clojure session or tool. Background mining or constant activity is a red flag.
Red Flags: If clojure.exe appears outside expected folders, runs when idle, lacks a Digital Signature, or uses persistent high resources, scan with antivirus. Watch for similarly named files like 'clojure32.exe'.
Why Is clojure.exe Running on My PC?
clojure.exe runs when you start a Clojure program or when tooling initializes a REPL, build task, or watcher. It may also remain active if a project uses a persistent nREPL server.
Reasons it's running:
- Active Clojure Session: You are actively running a Clojure program, REPL, or test suite; each session creates a JVM instance
- Background Tooling: IDE integrations (nREPL, pretty printers, linters) may keep a clojure.exe/JVM active
- Build or Dependency Task: Leiningen, Boot, or deps.edn tasks spawn JVMs to compile, test, or package your code
- Hot Reload / Watchers: Figwheel, shadow-cljs, or file watchers keep CLJ code changes active for reloads
- Startup Configuration: If Windows or your shell launches Clojure at login, clojure.exe will start on boot
Can I Disable or Remove clojure.exe?
Yes, you can disable clojure.exe. It's safe to close CLJ sessions when not in use and you can uninstall the Clojure distribution if you prefer a different setup.
How to Stop clojure.exe
- End Active Sessions: Stop the REPL from your IDE, or press Ctrl+C in the REPL to terminate the JVM
- Close Applications: Close all Clojure-enabled applications and editors
- End JVMs: Open Task Manager and end any java.exe/javaw.exe processes associated with clojure
- Prevent Startup: Disable any Windows startup entry or shell alias that launches clojure.exe
- Stop Background Tasks: In IDEs, disable watchers or disable 'start nREPL at launch' options
How to Uninstall Clojure
- ✔ Windows Settings => Apps => Apps & Features => Clojure => Uninstall
- ✔ Control Panel => Programs => Uninstall a program => Clojure => Uninstall
- ✔ Delete the Clojure distribution directory if you no longer need it
Common Problems: High CPU or Memory Usage
If clojure.exe is consuming excessive resources:
Common Causes & Solutions
- Large REPL session with loaded namespaces: Close unused namespaces or restart the REPL; consider lazy loading and trimming project scopes
- Heavy tooling extensions: Disable or remove unnecessary IDE plugins; minimize nREPL instrumentation
- Leiningen/Boot tasks: Limit parallel tasks; run with fewer cores; use profiles to reduce work
- Frequent file watchers: Disable extra watchers; configure only essential hot reload
- Outdated JVM or Clojure version: Update to latest stable Java and Clojure; ensure compatibility
- Memory pressure from Heap size: Adjust JVM heap in your launcher or tooling; use smaller dev profiles
Quick Fixes:
1. Use your IDE to stop the CLJ REPL sessions
2. Close unused Clojure tool windows and tabs
3. Restart clojure.exe with a smaller heap if configurable
4. Disable unnecessary extensions in your IDE
5. Update Java and Clojure to latest stable versions
Frequently Asked Questions
Is clojure.exe a virus?
No, the legitimate clojure.exe from the official Clojure project is not a virus. Verify the file path (C:\\Program Files\\Clojure\\clojure.exe) and a valid signer for safety.
Why is clojure.exe using so much CPU?
High CPU usually comes from large REPL sessions, heavy mutual references, or your IDE's nREPL connections. Use the CLJ task manager in your IDE to identify culprits, then optimize or close them.
Can I delete clojure.exe?
Yes, you can uninstall the Clojure distribution if you no longer need it. This will remove clojure.exe and related tools from your system.
Can I disable clojure.exe?
Yes, you can disable it by preventing startup, stopping active sessions, and closing IDEs that spawn clojure.exe.
Why is clojure.exe running at startup?
If a startup script or IDE extension launches Clojure on login, clojure.exe may start automatically. Remove or disable that startup entry.
Why are there so many clojure.exe processes?
Clojure uses a JVM-based, multi-process approach; each REPL session or tool may spawn its own JVM, leading to multiple java processes associated with clojure.exe.