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README.md

Clojure Startup Profiling

This is a profiling test to see where the time goes when a Clojure application boots on the desktop. The test program is the following:

(ns hello.core
  (:gen-class))

(defn -main []
  (println "Hello world"))

It is run from the command line like any other Java program using various techniques to profile the startup time.

Environment

Tool Version
Java Runtime Java(TM) SE Runtime Environment (build 1.7.0_60-b19)
JVM Java HotSpot(TM) 64-Bit Server VM (build 24.60-b09, mixed mode)
Clojure 1.6.0
Operating System Ubuntu Linux 13.10 64 bit
Computer Lenovo Yoga 2 Pro i7-4500U 1.8 GHz, 4 GB RAM, 256 GB SSD

Setup for all experiments

Compile Clojure sources:

java -cp src/clj:../../clojure-1.6.0.jar -Dclojure.compile.path=classes clojure.lang.Compile hello.core

No profiling (for comparison)

This test runs the program without any profiling. This is to provide a baseline to see how much overhead the different profiling techniques introduce.

Execute program:

java -cp ../../clojure-1.6.0.jar:classes hello.core

Class loading timestamps

This test introduces a simple Java profiling agent to get timestamps for class loading events. The profiling agent wraps class loading to print the current time before each class is loaded. By observing these times one can infer roughly the amount of wall time spent on JVM startup, Clojure runtime startup, loading core Clojure classes, and executing the user's Clojure code. This introduces a small amount of overhead.

Compile and build Java profiling agent:

javac -d classes src/java/ClassLoadTracer.java
jar -cvfm classes/tracer.jar src/java/manifest.mf classes/ClassLoadTracer*.class

Execute program with profiling agent:

java -javaagent:classes/tracer.jar -cp ../../clojure-1.6.0.jar:classes hello.core

Tracing

This uses the YourKit Java profiler to get more detailed profiling information. The YourKit profiler must be available through the YJP_PATH environment variable.

Execute program with profiling agent:

java -agentpath:$YJP_HOME/bin/linux-x86-64/libyjpagent.so=dir=logs,logdir=logs,probe_disable=*,quiet,disablealloc,disablestacktelemetry,disableexceptiontelemetry,disabletracing,tracing -cp $YJP_HOME/lib/yjp.jar:../../clojure-1.6.0.jar:classes hello.core

Sampling

The YourKit sampling profiler can also be used by substituting sampling for tracing.

Execute program with profiling agent:

java -agentpath:$YJP_HOME/bin/linux-x86-64/libyjpagent.so=dir=logs,logdir=logs,probe_disable=*,quiet,disablealloc,disablestacktelemetry,disableexceptiontelemetry,disabletracing,sampling -cp $YJP_HOME/lib/yjp.jar:../../clojure-1.6.0.jar:classes hello.core