Re: Proposed new Java feature

From:
"Mike Schilling" <mscottschilling@hotmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Sun, 27 May 2012 11:00:41 -0700
Message-ID:
<jptq42$1jo$1@dont-email.me>
"markspace" <-@.> wrote in message news:jptkmp$vbg$1@dont-email.me...

On 5/26/2012 4:11 PM, Mike Schilling wrote:

Proposed feature: a static method on Thread that clears all ThreadLocals
for
the current thread.


I can see your points. However, I don't have any real experience with
ThreadLocal, and when a neophyte agrees with your argument, that's a red
flag.

Here's a blog where someone seems to have the same issue as you.

<http://weblogs.java.net/blog/jjviana/archive/2010/06/10/threadlocal-thread-pool-bad-idea-or-dealing-apparent-glassfish-memor>

At the end of the comments, there's a suggestion to use
ThreadLocal::remove(), with the implication that it allows the thread
local variable to be garbage collection. Is there a reason that doesn't
work for you?


That acts on an individual ThreadLocal (and works quite well), but it
doens't allow removing all ThreadLocals that might have been accumlated.

My other thought is that "for the current thread" could be improved with
"for a given thread." So, inside an Executor, I can just call

  Thread t = ...
  // .. use the thread ..
  Thread.removeLocals( t );
  // now add the thread back into the pool...

And this seems better because I don't have to rely on the users of a
thread remembering to do it themselves. External control seems better
here.


Same comment. What I'm asking for is Thread.removeLocals(), which doesn't
currently exist.

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