Re: java thread for core 2 due processors

Joshua Cranmer <Pidgeot18@verizon.invalid>
Mon, 17 Aug 2009 15:52:58 -0400
Motaz K. Saad wrote:

I am working on file processing (large number of files) which is
totally independent task for each file. I want to speedup processing
using java thread but I do not want overwhelm my processor (core 2 due
processor) with all threads at the same time.

Depending on what you are exactly doing, it seems to me that doing two
threads at a time will not be maximizing throughput. They could be
spending most of their time waiting around for disk I/O. On modern
processors, one thread-per-core is generally not optimal; ISTR hearing
somewhere that the correct number is about 1.5-2 per core.

I want to run 2 parallel threads simultaneously and wait until they
finish then run the next 2 threads. furthermore, each thread allocate
large amount of memory so I need to de-allocate the thread after
collecting the result from it.

As long as you watch who holds references to what, the GC will clear
memory up itself. I think it would generally be sufficient to make sure
that you don't keep references to the threads unless necessary--good
programming practices will likely confine the leaks.

I would appreciate if anyone direct my to similar set example
I would appreciate guideline and help

The first thing to recommend is that you have a grasp on how to do
concurrent programming. If your tasks do not communicate to each other
or to the main program, you probably don't have any thread-safety issues.

The best way to actually implement this is probably with the new from
Java 5 ExecutorService API, as others have stated.

Beware of bugs in the above code; I have only proved it correct, not
tried it. -- Donald E. Knuth

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