Re: Why is java consumer/producer so much faster than C++

From	Luca Risolia <luca.risolia@studio.unibo.it>
Newsgroups	comp.lang.c++, comp.programming.threads
Subject	Re: Why is java consumer/producer so much faster than C++
Date	2012-07-23 02:03 +0200
Organization	Aioe.org NNTP Server
Message-ID	<jui4cg$d5a$1@speranza.aioe.org> (permalink)
References	<juht3o$a3a$1@news.albasani.net> <ba6e5833-f9a2-428e-815b-aad0ebdf3c55@s6g2000pbi.googlegroups.com> <jui2a3$a3a$2@news.albasani.net>

Cross-posted to 2 groups.

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On 23/07/2012 01:28, Melzzzzz wrote:
> Still twice as fast as c++.
> What it looks like, is that c++ spends much more time in syscalls
> (futex) than java and that explains big difference.

A lock-free "BlockingQueue" would probably be more efficient.
You can also try to implement your Queue with std::array instead of 
std::deque and see how it performs.

In the C++ version change:

	while (queue_.size() >= capacity_)c_full_.wait(lock);
with
	c_full_.wait(lock, [this]{return queue_.size() < capacity_;});

and
	while (queue_.empty())c_empty_.wait(lock);
with
	c_empty_.wait(lock, [this]{return !queue_.empty();});

Also use a std::lock_guard in empty() instead of std::unique_lock. The 
former is faster.

(On a side note, the C++ version you have given does not have the best 
possible interface for a thread-safe queue)

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Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-22 23:59 +0200
  Re: Why is java consumer/producer so much faster than C++ Joshua Maurice <joshuamaurice@gmail.com> - 2012-07-22 15:42 -0700
    Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-23 01:28 +0200
      Re: Why is java consumer/producer so much faster than C++ Luca Risolia <luca.risolia@studio.unibo.it> - 2012-07-23 02:03 +0200
        Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-23 12:17 +0200
          Re: Why is java consumer/producer so much faster than C++ Luca Risolia <luca.risolia@studio.unibo.it> - 2012-07-24 00:33 +0200
            Re: Why is java consumer/producer so much faster than C++ Bo Persson <bop@gmb.dk> - 2012-07-24 19:50 +0200
  Re: Why is java consumer/producer so much faster than C++ Juha Nieminen <nospam@thanks.invalid> - 2012-07-23 06:37 +0000
    Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-23 12:33 +0200
      Re: Why is java consumer/producer so much faster than C++ Juha Nieminen <nospam@thanks.invalid> - 2012-07-23 11:46 +0000
        Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-23 15:33 +0200
  Re: Why is java consumer/producer so much faster than C++ Zoltan Juhasz <zoltan.juhasz@gmail.com> - 2012-07-23 06:57 -0700
    Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-23 18:42 +0200
      Re: Why is java consumer/producer so much faster than C++ Howard Hinnant <howard.hinnant@gmail.com> - 2012-07-23 13:23 -0700
        Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-24 00:32 +0200
          Re: Why is java consumer/producer so much faster than C++ Howard Hinnant <howard.hinnant@gmail.com> - 2012-07-23 18:11 -0700
            Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-24 11:21 +0200
            Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-24 21:45 +0200
              Re: Why is java consumer/producer so much faster than C++ Luca Risolia <luca.risolia@studio.unibo.it> - 2012-07-24 23:24 +0200
                Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-25 00:48 +0200
                Re: Why is java consumer/producer so much faster than C++ Luca Risolia <luca.risolia@studio.unibo.it> - 2012-07-25 01:21 +0200
              Re: Why is java consumer/producer so much faster than C++ Howard Hinnant <howard.hinnant@gmail.com> - 2012-07-24 17:35 -0700
              Re: Why is java consumer/producer so much faster than C++ Luca Risolia <luca.risolia@studio.unibo.it> - 2012-07-26 21:19 +0200
                Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-26 21:56 +0200
                Re: Why is java consumer/producer so much faster than C++ Luca Risolia <luca.risolia@studio.unibo.it> - 2012-07-26 22:15 +0200
                Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-26 23:01 +0200
                Re: Why is java consumer/producer so much faster than C++ Luca Risolia <luca.risolia@studio.unibo.it> - 2012-07-26 23:12 +0200
                Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-27 00:24 +0200
                Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-27 00:48 +0200
                Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-27 05:43 +0200
                Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-27 07:43 +0200
                Re: Why is java consumer/producer so much faster than C++ Marc <marc.glisse@gmail.com> - 2012-07-26 21:10 +0000
                Re: Why is java consumer/producer so much faster than C++ Donkey Hottie <donkey@fredriksson.dy.fi> - 2012-07-27 01:05 +0300
                Re: Why is java consumer/producer so much faster than C++ Paavo Helde <myfirstname@osa.pri.ee> - 2012-07-26 17:12 -0500
        Re: Why is java consumer/producer so much faster than C++ yatremblay@bel1lin202.(none) (Yannick Tremblay) - 2012-07-24 12:51 +0000
          Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-24 17:47 +0200
            Re: Why is java consumer/producer so much faster than C++ yatremblay@bel1lin202.(none) (Yannick Tremblay) - 2012-07-25 08:09 +0000
              Re: Why is java consumer/producer so much faster than C++ Howard Hinnant <howard.hinnant@gmail.com> - 2012-07-25 08:46 -0700
  Re: Why is java consumer/producer so much faster than C++ Dombo <dombo@disposable.invalid> - 2012-07-23 22:57 +0200
    Re: Why is java consumer/producer so much faster than C++ Joshua Maurice <joshuamaurice@gmail.com> - 2012-07-23 21:54 -0700
      Re: Why is java consumer/producer so much faster than C++ Jorgen Grahn <grahn+nntp@snipabacken.se> - 2012-07-24 12:50 +0000
  Re: Why is java consumer/producer so much faster than C++ James Kanze <james.kanze@gmail.com> - 2012-07-29 03:27 -0700
    Re: Why is java consumer/producer so much faster than C++ Melzzzzz <mel@zzzzz.com> - 2012-07-29 14:40 +0200
  Re: Why is java consumer/producer so much faster than C++ Ricardo Nabinger Sanchez <rnsanchez@wait4.org> - 2012-08-14 22:48 +0000

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