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From "Shay Banon (JIRA)" <>
Subject [jira] [Commented] (LUCENE-5086) RamUsageEstimator causes AWT classes to be loaded by calling ManagementFactory#getPlatformMBeanServer
Date Thu, 04 Jul 2013 10:07:20 GMT


Shay Banon commented on LUCENE-5086:

The Java version on the Mac is the latest one:

java version "1.6.0_51"
Java(TM) SE Runtime Environment (build 1.6.0_51-b11-457-11M4509)
Java HotSpot(TM) 64-Bit Server VM (build 20.51-b01-457, mixed mode)

Regarding the catch, I think Throwable is the right exceptions to catch here. Catch all, who
cares, you don't want a bug in the JVM that throws an unexpected runtime exception to cause
Lucene to break the APP completely because its a static block, and I have been right there
a few times. But if you feel differently, go ahead and change it to explicitly catch whats
> RamUsageEstimator causes AWT classes to be loaded by calling ManagementFactory#getPlatformMBeanServer
> -----------------------------------------------------------------------------------------------------
>                 Key: LUCENE-5086
>                 URL:
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Shay Banon
>            Assignee: Dawid Weiss
> Yea, that type of day and that type of title :).
> Since the last update of Java 6 on OS X, I started to see an annoying icon pop up at
the doc whenever running elasticsearch. By default, all of our scripts add headless AWT flag
so people will probably not encounter it, but, it was strange that I saw it when before I
> I started to dig around, and saw that when RamUsageEstimator was being loaded, it was
causing AWT classes to be loaded. Further investigation showed that actually for some reason,
calling ManagementFactory#getPlatformMBeanServer now with the new Java version causes AWT
classes to be loaded (at least on the mac, haven't tested on other platforms yet). 
> There are several ways to try and solve it, for example, by identifying the bug in the
JVM itself, but I think that there should be a fix for it in Lucene itself, specifically since
there is no need to call #getPlatformMBeanServer to get the hotspot diagnostics one (its a
heavy call...).
> Here is a simple call that will allow to get the hotspot mxbean without using the #getPlatformMBeanServer
method, and not causing it to be loaded and loading all those nasty AWT classes:
> {code}
>     Object getHotSpotMXBean() {
>         try {
>             // Java 6
>             Class sunMF = Class.forName("");
>             return sunMF.getMethod("getDiagnosticMXBean").invoke(null);
>         } catch (Throwable t) {
>             // ignore
>         }
>         // potentially Java 7
>         try {
>             return ManagementFactory.class.getMethod("getPlatformMXBean", Class.class).invoke(null,
>         } catch (Throwable t) {
>             // ignore
>         }
>         return null;
>     }
> {code}

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