[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
If I[he] were king: A proposal for fixing the Java programming language's threading problems
An interesting article by Allen Holub with the above title appears here:
As someone who implements sysThreadCreate, sysMonitorEnter and most of the
these proposals would boil down to I find them very interesting.
Would their implementation be welcomed as a sensible evolutionary
or a missed opportunity for introducing more radical elements?
>From the commercial world's point of view my vision is constrained by the
of reliability, speed and scalability of a particular JVM implementation
and the need
for a common standard - to prevent fragmentation of the Java market which
then be very much more vulnerable to spoiler initiatives like '.net'
However (and remembering the above), I cannot help thinking that having
humans manage concurrency
too much (especially in a world of weak consistency MP boxes, parallelising
optimising C compilers that reorder statements, (explicit) parallelising
processors etc etc) is akin to the time when humans wrote
code overlays before we had virtual memory subsystems.
Is the final goal not one where the amount of parallelism is left to the
and humans are left to specify as little (or as much) as they want to .
If I have a code block like:
y = 4;
Then I might infer that both assignments run on the same thread, on the
in a particular order and have even happened at all by the time the "}" is
Down at the bit level, all of these assumptions are getting harder to
support in modern systems,
(and a cause of defects on weakly consistent;/RMO machines)
so why are they so hard-wired into our favourite languages? Are we just
stuck in 'linear' mode
as Edward De Bono would say or is this a vital part of making a programming
Sure,some algorithms are most clearly represented as a stateful thread that
created and destroyed and given something to do (wait on a mutex, condition
when we really don't want it to do anything. It is just that I cannot help
feeling that I
would rather have the system deal with the actual thread physical threads
most of the time.
Does this lead us to the 'task' engine, munching through requests, such as
or a more functional language (like Erlang?) or one based on a particular
process algebra (like Pict?)
or libraries like JCSP and CTJ?
I would be very interested in your thoughts regarding the longer term view.
PS. In this note my views are my own and don't represent any IBM
position on Java threads or related areas.
IBM Java Technology Centre,
IBM Hursley, UK.
Notes: Gordon Hutchison/UK/IBM
Phone: (+44)/(0) 1962 815646 (Internal IBMUK-245646)