[concurrency-interest] regarding synchronized command and object'sfootprint

√iktor Ҡlang viktor.klang at gmail.com
Sun Mar 4 06:35:53 EST 2012


Parking threads is cheap...
On Mar 4, 2012 12:24 PM, "William Louth (JINSPIRED.COM)" <
william.louth at jinspired.com> wrote:

>  fix a relatively small memory allocation retention problem with a
> significant memory allocation rate problem...sounds great
>
> On 04/03/2012 12:05, √iktor Ҡlang wrote:
>
>
>
> On Sun, Mar 4, 2012 at 11:49 AM, David Holmes <davidcholmes at aapt.net.au>wrote:
>
>>  That is correct in Hotspot. If contention occurs a heavyweight monitor
>> has to be created (this is called monitor inflation). There is a freelist
>> of inflated monitors - if the list is non-empty then one of those monitors
>> is used, else a new one is created.  If the monitor becomes idle it can be
>> returned to the freelist during a safepoint. The monitors once created are
>> never destroyed.
>>
>
>  Another very good reason to stick to CAS unless the exact semantics of
> synchronized is desirable. But technically, if sequential access is
> desired, one can still avoid synchronization by switching to the correct
> model for that - actors.
>
>  Cheers,
> √
> Â
>
>>  Â
>> It has nothing to do with "barrier info" whatever that might be.
>>  Â
>> David Holmes
>>   Â
>> -----Original Message-----
>> *From:* concurrency-interest-bounces at cs.oswego.edu [mailto:
>> concurrency-interest-bounces at cs.oswego.edu]*On Behalf Of *Yechiel Feffer
>> *Sent:* Sunday, 4 March 2012 7:56 PM
>> *To:* 'Concurrency-interest at cs.oswego.edu'
>> *Subject:* [concurrency-interest] regarding synchronized command and
>> object'sfootprint
>>
>>   Hi
>>
>> I heard a claim that execution of synchronized(object)  command  (maybe
>> contended synchronized) raises the  object footprint in the java heap- a
>> raise the (partially ?) remains even after all threads exited the
>> synchronized block.
>>
>> Is it correct ? Is it related to barrier info java maintains ?
>>
>> Â
>>
>> Regards
>>
>> Yechiel
>>
>>
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>>
>
>
>  --
> Viktor Klang
>
> Akka Tech Lead
> Typesafe <http://www.typesafe.com/>Â - The software stack for
> applications that scale
>
> Twitter: @viktorklang
>
>
>
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