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

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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	Mon, 23 Jul 2012 02:03:28 +0200
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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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Thread

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++ 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++ 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++ Ricardo Nabinger Sanchez <rnsanchez@wait4.org> - 2012-08-14 22:48 +0000

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