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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)