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Groups > comp.lang.java.programmer > #30919
| From | Robbie Brown <rob@example.com> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: a simple multi-thread question |
| Date | 2015-01-26 18:05 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <ma5vk9$vu7$1@dont-email.me> (permalink) |
| References | <60c8877a-8321-4ba5-ab9a-8ccabd77874b@googlegroups.com> <ma5o15$s9p$1@dont-email.me> |
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.
--
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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