Comments on: ThreadLocal in One Click http://blogs.jetbrains.com/idea/2009/10/threadlocal-in-one-click/ tips & tricks, news, how-to's Mon, 13 Feb 2012 08:06:24 +0000 http://wordpress.org/?v=2.6.5 By: Niels Harremoes http://blogs.jetbrains.com/idea/2009/10/threadlocal-in-one-click/#comment-173195 Niels Harremoes Sat, 19 Mar 2011 16:12:27 +0000 http://blogs.jetbrains.com/idea/?p=2230#comment-173195 Sorry to revive an old thread, but I just stumbled upon this. I think this is a very dangerous quickfix, since it introduces a memory leak in an app server environment, where you want your classloaders to be unloadable? Threadlocals are implemented as per-thread weak hashmaps. If the value contains a reference to the key, the values will never die, before the thread dies. The value in this case is a SAXBuilder instance. This, of course has a reference to the SAXBuilder.class, which has a reference to the classloader for jdom, which has a reference to the JDOMUtil class, which has a reference to the static field, i.e. the ThreadLocal instace. So the loop is tied, and your jdom classloader can now never be garbage collected :-( So IF the initial value in any way references the classloader which loaded the containing class, that classloader will be uncollectable. This may or may not be a problem, depending on the use case. But I think it is a bit too dangerous to have as a quickfix? Sorry to revive an old thread, but I just stumbled upon this. I think this is a very dangerous quickfix, since it introduces a memory leak in an app server environment, where you want your classloaders to be unloadable?

Threadlocals are implemented as per-thread weak hashmaps. If the value contains a reference to the key, the values will never die, before the thread dies.

The value in this case is a SAXBuilder instance. This, of course has a reference to the SAXBuilder.class, which has a reference to the classloader for jdom, which has a reference to the JDOMUtil class, which has a reference to the static field, i.e. the ThreadLocal instace. So the loop is tied, and your jdom classloader can now never be garbage collected :-(

So IF the initial value in any way references the classloader which loaded the containing class, that classloader will be uncollectable.
This may or may not be a problem, depending on the use case. But I think it is a bit too dangerous to have as a quickfix?

]]> By: Markus Jevring http://blogs.jetbrains.com/idea/2009/10/threadlocal-in-one-click/#comment-127409 Markus Jevring Mon, 01 Mar 2010 13:06:23 +0000 http://blogs.jetbrains.com/idea/?p=2230#comment-127409 Unfortunately, this wonderful little trick doesn't work in the Community Edition =( Unfortunately, this wonderful little trick doesn’t work in the Community Edition =(

]]> By: anjan bacchu http://blogs.jetbrains.com/idea/2009/10/threadlocal-in-one-click/#comment-118709 anjan bacchu Fri, 30 Oct 2009 13:29:19 +0000 http://blogs.jetbrains.com/idea/?p=2230#comment-118709 hi there, cool! how long before eclipse copies it ? (as it's been doing for the last 8 years :-) ) BR, ~A hi there,

cool!

how long before eclipse copies it ? (as it’s been doing for the last 8 years :-) )

BR,
~A

]]> By: Felipe Cypriano http://blogs.jetbrains.com/idea/2009/10/threadlocal-in-one-click/#comment-118703 Felipe Cypriano Fri, 30 Oct 2009 11:52:06 +0000 http://blogs.jetbrains.com/idea/?p=2230#comment-118703 These "little" details makes idea the best IDE These “little” details makes idea the best IDE

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