Garbage Collector question?

[davids@xxxxxxxxxxxxxxxx (David Soroko)]

Is this behavior part of some spec or is a description of a particular VM
implementation?

I vaguely remember that some (early) versions of hot spot were so aggressive
in their GC algorithm
that local variables were GCed while the were still in scope and not used
beyond certain point.
I am not sure that this approach was in any sense illegal, just strange.

--

============================================
David Soroko
mailto:davids@xxxxxxxxxxxxxxxx
http://www.geocities.com/SiliconValley/Campus/1628/
Group Manager, Core Technologies
Manna Inc.
============================================


>
> > -----Original Message-----
> > From: Yogesh Pandeya [mailto:yogesh@xxxxxxxxx]
> > Sent: Tuesday, November 30, 1999 9:15 PM
> > To: 'Shrihari.S.C'; Java Mail List
> > Subject: RE: Garbage Collector question?
> >
> >
> > Hi Srihari,
> > Its not always the case that gc runs as a low priority thread.
> > When the JVM runs short of memory, gc runs at high priority to
> > reclaim space. If it could not get space by gc, it(JVM) gets more
> > memory from the system.(correct me Gurus if I am wrong)
> >
> > About temperory objects....
> > If you are declaring an object handle locally, and assigning new
> > object to it, it will be gabage collected if it goes out of
> > scope. If you are declaring the handle at the top level, and
> > allocate a new object to it, it will hang around with you unless
> > you assign it to null. This kind of memory leaks are programer's
> > creation and he/she has to take care of it.
> > If you need to create many objects locally many times, its always
> > a good idea to use object pool as it will improve the performance
> > significantly as "new" is a costly affair.
> > Does this make sense or I am missing somthing???
> > regards,
> > Yogesh
> >
> >
> > -----Original Message-----
> > From:	Shrihari.S.C [SMTP:sriharis@xxxxxxxxxxxxxxxxxxxx]
> > Sent:	Tuesday, November 30, 1999 2:41 PM
> > To:	Java Mail List
> > Cc:	yogesh@xxxxxxxxx
> > Subject:	RE: Garbage Collector question?
> >
> > Hi Yogesh,
> > 	The System.gc() is a low priority thread that cleans those
> > set of objects
> > that are not from the primordial class loader , but from the
> custom class
> > loader and those which has been assigned null. But considering
> > the fact that
> > the class contains too many objects that have been temporarily created
> > because of some intermediate computation and have not been
> assigned null,
> > before which the computation is exited, the System.gc() siezes to work
> > because of improper set of unreferenced objects to be
> > deallocated. What do u
> > think can be set of other options left out to see this problem ?
> > 			Regards
> > 								Shrihari
> > > -----Original Message-----
> > > From: Yogesh Pandeya [mailto:yogesh@xxxxxxxxx]
> > > Sent: Tuesday, November 30, 1999 7:32 PM
> > > To: 'magesh@xxxxxxxxxxxxxxxx'; 	 punam
> > > chordia
> > > Subject: RE: Garbage Collector question?
> > >
> > >
> > >
> > > Hi Magesh,
> > > Another sequence on gc!!!! Anyway.....
> > >
> > > Putting System.gc() doesn't guarantee that it will run when you
> > > want to. Its VM's prerogative to run gc or not. It is guaranteed
> > > run at the point you put System.gc(), only if you run the
> > > application with -noclassgc (or -Xnoclassgc) option.
> > > Other point to note is, if you are creating objects temporarily,
> > > you can use an object pool and reuse your objects. There is good
> > > article this month's Javaworld.
> > > Hope it helps,
> > > cheers,
> > > Yogesh
> > >
> > >      -----Original Message-----
> > > From:	magesh@xxxxxxxxxxxxxxxx [SMTP:magesh@xxxxxxxxxxxxxxxx]
> > > Sent:	Tuesday, November 30, 1999 1:23 PM
> > > To:	advanced-java@xxxxxxxxxxxxxxxx; punam chordia
> > > Subject:	RE: Garbage Collector question?
> > >
> > >
> > >
> > > Hi,
> > >
> > > Does this guarantee that the System.gc() will run without
> > getting context
> > > switched
> > > because it has a low priority??
> > >
> > > thanks,
> > > mmp.
> > >
> > >
> > >
> > >
> > >
> > > punam chordia <punamac@xxxxxxx> on 11/30/99 02:44:03 AM
> > >
> > > To:   Mageshkumar Maruthapillai/Technology Providers/lk
> > > cc:
> > > Subject:  RE: Garbage Collector question?
> > >
> > >
> > >
> > >
> > > We also had a similar problem.
> > > U can run garbage collector explicitly by writing the
> following line of
> > > code,
> > > System.gc();
> > > I hope it helps you.
> > > Punam Chordia
> > > Software Engineer
> > > ITL Infosys, Pune.
> > > Ph. 91-020-647420/1 Extension: 1046
> > > > -----Original Message-----
> > > > From:   magesh@xxxxxxxxxxxxxxxx [SMTP:magesh@xxxxxxxxxxxxxxxx]
> > > > Sent:   Tuesday, November 30, 1999 PM 01:06
> > > > To:     advanced-java@xxxxxxxxxxxxxxxx
> > > > Subject:     Garbage Collector question?
> > > >
> > > >
> > > >
> > > > Hi,
> > > >
> > > >     My server code is consuming a lot of memory dur to a
> large number
> > > > of objects being created temporarily.
> > > >
> > > > I want to be able to get a reference to the garbage collector
> > > > of the virtual machine so that I can give it a high priority to it
> > > > very short intervals intermittently.
> > > >
> > > >
> > > > Is there a way to get the reference to the garbage collector?
> > > >
> > > >
> > > > any help is appreciated.
> > > >
> > > > thanks,
> > > > mmp
> > > >
> > > >
> > > >
> > > > ---
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> > >
> > >
> > >
> > >
> > >
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> >
>
>
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