Following the current Quick Start document at
https://github.com/clojure/clojurescript/wiki/Quick-Start, I found that
there is a roughly one minute long extra wait after closure optimizations
have been applied before the JVM exits.
My setup: hello word example as on the Quick Start guide, build.clj is:
(require 'cljs.closure)
(cljs.closure/build "src"
{:output-to "out/main.js"
:verbose true})
With this build call (no optimizations), compile from cold is under 3s.
Adding simple optimizations to the above call:
(cljs.closure/build "src"
{:output-to "out/main.js"
:optimizations :simple
:verbose true})
makes the process take over a minute. The CPU is only active for a few
seconds at the beginning, for the remainder of the time nothing appears
to be happening (the output file is done and remains unchanged after the
first few seconds). Looking at the process in jvisualvm shows threads
called jscompiler that are also idle after a bit of activity at the
beginning. My suspicion is that there is a timeout somewhere but I have
not found exactly where. It looks as if it is in Google Closure as I can't find
any reference to threads called jscompiler in the ClojureScript sources.
A Thread dump during the wait time shows a jscompiler thread to be waiting:
"jscompiler" #16 prio=5 os_prio=0 tid=0x00007f2304efb800 nid=0x5032 waiting
on condition [0x00007f22e4713000]
java.lang.Thread.State: TIMED_WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x000000008725e6f8> (a
java.util.concurrent.SynchronousQueue$TransferStack)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
at
java.util.concurrent.SynchronousQueue$TransferStack.awaitFulfill(SynchronousQueue.java:460)
at
java.util.concurrent.SynchronousQueue$TransferStack.transfer(SynchronousQueue.java:362)
at java.util.concurrent.SynchronousQueue.poll(SynchronousQueue.java:941)
at
java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1066)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Locked ownable synchronizers:
- None
Adding a simple:
(System/exit 0)
after the cljs.closure/build call reduces compilation by almost exactly
a minute back down to 8 seconds with {:optimizations :simple}.
System is Debian Linux (testing), Oracle JDK 8, java -version:
java version "1.8.0_40"
Java(TM) SE Runtime Environment (build 1.8.0_40-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.40-b25, mixed mode)
Compilation command line is:
java -cp cljs.jar:src clojure.main build.clj
Has anybody else experienced this? Is there a way to reduce the wait?
Regards,
Caspar
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