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Groups > comp.lang.java.programmer > #30928
| From | Robbie Brown <rob@example.com> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: a simple multi-thread question |
| Date | 2015-01-26 19:51 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <ma65qf$tlm$1@dont-email.me> (permalink) |
| References | <60c8877a-8321-4ba5-ab9a-8ccabd77874b@googlegroups.com> <ma5o15$s9p$1@dont-email.me> <ma5vk9$vu7$1@dont-email.me> <54c686fe$0$288$14726298@news.sunsite.dk> |
On 26/01/15 18:27, Arne Vajhøj wrote:
> On 1/26/2015 1:05 PM, Robbie Brown wrote:
>> On 26/01/15 15:55, Eric Sosman wrote:
>>> On 1/26/2015 10:40 AM, John wrote:
>>>>
>>>> I am amazed at what I saw:
>>>>
>>>> synchronized private void print()
>>>> {
>>>> System.out.println("printing A");
>>>> System.out.println("printing B");
>>>> System.out.println("printing C");
>>>> }
>>>> [... he gets interleaved output ...]
>>>
>>> Each Java object has its own lock ("monitor"), independent of the
>>> locks belonging to other Java objects. When you call a synchronized
>>> instance method, Java acquires the lock of the "this" object before
>>> proceeding, and releases it when the method finishes. If there are
>>> several object instances floating around, there are several "this"
>>> and several independent locks.
>>>
>>>> I thought the method is atomic.
>>>
>>> No. Synchronization is not about methods (or code blocks), but
>>> about objects: You lock the *object*, not a method.
>>
>> Are you sure?
>>
>> If you have a class with two methods and one (or more) of them is
>> synchronized and one (or more) isn't then a thread can obtain the lock
>> on an instance of that class which locks out all other threads from the
>> synchronized methods but the non synchronized methods of that instance
>> are still available to other threads.
>>
>> At least that's how I remember it.
>
> I think that is what Eric is saying.
Really?
"No. Synchronization is not about methods (or code blocks), but
about objects: You lock the *object*, not a method"
seems pretty clear to me. 'still, I'm sure you know best.
--
Not floundering ... just fishing
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a simple multi-thread question John <xsli2@yahoo.com> - 2015-01-26 07:40 -0800
Re: a simple multi-thread question Arne Vajhøj <arne@vajhoej.dk> - 2015-01-26 10:53 -0500
Re: a simple multi-thread question Robert Klemme <shortcutter@googlemail.com> - 2015-01-26 07:54 -0800
Re: a simple multi-thread question Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-01-26 10:55 -0500
Re: a simple multi-thread question Robbie Brown <rob@example.com> - 2015-01-26 18:05 +0000
Re: a simple multi-thread question Robbie Brown <rob@example.com> - 2015-01-26 18:08 +0000
Re: a simple multi-thread question Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-01-26 17:19 -0500
Re: a simple multi-thread question Arne Vajhøj <arne@vajhoej.dk> - 2015-01-26 13:27 -0500
Re: a simple multi-thread question Robbie Brown <rob@example.com> - 2015-01-26 19:51 +0000
Re: a simple multi-thread question Jukka Lahtinen <jtfjdehf@hotmail.com.invalid> - 2015-01-28 21:55 +0200
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