[concurrency-interest] OpenJDK Project Loom - lightweight threads for Java

Joshua Bloch jbloch at gmail.com
Wed Oct 25 15:34:28 EDT 2017


This is very similar in spirit to the "many-to-few" threading model that
was popular in the '90s. You can read about it in Butenhof's *Programming
with POSIX Threads (Addison-Wesley, 1997)*, §5.6.3. The concept pretty much
died on the vine when kernel threads got faster and cheaper, but everything
old is new again.

BTW, I believe that by far the most important thing this project could do
for the average Java programmer is to provide yield iterators, à la C#.
Writing your own iterator is difficult, and writing one for collections
whose traversal is inherently recursive is extremely difficult: you have to
translate the recursive algorithm into an iterative one by maintaining an
explicit stack instead of using the thread's stack. Giving people yield
iterators makes it trivial to write iterators. This should be a tier 1 use
case: If a proposed solution can't handle it, the solution should be
repaired or discarded.

Josh

On Wed, Oct 25, 2017 at 11:42 AM, Andrig Miller <anmiller at redhat.com> wrote:

>
>
> On Wed, Oct 25, 2017 at 11:31 AM, thurstonn <thurston at nomagicsoftware.com>
> wrote:
>
>> Love it.
>>
>> BTW, for those with institutional memory, isn't that what "green threads"
>> more or less were meant to be, back in the earlier days of Java?  Before
>> my
>> time, and I never used them . . .
>>
>
> ​If memory serves me correctly, green threads were only present for
> platforms that didn't have threads in their kernel.
>
> Andy
>>
>>
>>
>>
>> --
>> Sent from: http://jsr166-concurrency.10961.n7.nabble.com/
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>
>
>
> --
> Andrig (Andy) T. Miller
> Global Platform Director, Middleware
> Red Hat, Inc.
>
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