On Feb 11, 2015, at 2:43 AM, David Holmes <david.hol...@oracle.com> wrote:
> Adding Doug Lea.
>
> On 11/02/2015 12:51 AM, Paul Sandoz wrote:
>> On Feb 10, 2015, at 3:39 PM, Chris Hegarty <chris.hega...@oracle.com> wrote:
>>>>
>>>> Adding native methods to 166 classes will introduce another form of
>>>> dependency on the platform that i would prefer to avoid.
>>>
>>> Right. And I suspect that the separate distributable of 166, outside of the
>>> Java Platform, would not want to have to carry a separate platform specific
>>> native library.
>>
>> Yes.
>
> Right and for that reason jsr166 distribution would not want to have to know
> whether to use Thread or Unsafe.
>
And that's why it should just be the former for the Java 9 platform and beyond.
The general strategy is to reduce dependency on Unsafe, including for 166
classes. The VarHandles effort is part of that strategy to replace Unsafe
enhanced access with a public alternative that is safe and just as performant.
>>
>>>
>>>>> But I don't see any reason why we couldn't move the implementation from
>>>>> unsafe.cpp to jvm.cpp and invoke via a native method implementation of
>>>>> LockSupport. It would still be just as "unsafe" of course.
>>>>>
>>>>
>>>> Can you think of any reasons, beyond that of "don't touch the core
>>>> classes", why we cannot copy this functionality over to java.lang.{*,
>>>> Thread} ?
>>>
>>> Would you be thinking of making the changes public, i.e. new standard API
>>> on java.lang.Thread ?
>>>
>>
>> Yes, j.l.Thread seems like the ideal location :-)
>
> I don't see any point in moving it to Thread now. The public supported API
> already exists in LockSupport.
Yes, but as i said the point is to tease apart the internal dependencies
between the platform and LockSupport class. (A simple solution is to copy and
rename this class to java.lang.ThreadSupport :-) .)
> The issue is not LockSupport versus Thread, but the use of Unsafe.
>
It's because LockSupport uses Unsafe to access non-public fields of Thread, and
i also want to break that internal dependency.
I presume that LockSupport was created because agreement was not reached to add
such core *thread*-based functionality to Thread. I dunno why such agreement
was not reached, but so far i am not hearing any compelling technical reasons.
Paul.
<snip>
> As I said you'd have to deprecate it in 9 with an intent to remove in 10 -
> assuming you are even allowed to do that.
>
Opinions differ but i think we should be more serious about removing stuff that
has been marked deprecated for one major release if the intent to do so is made
clear when deprecating.
