From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 24152 invoked by alias); 19 Dec 2011 11:52:12 -0000 Received: (qmail 24141 invoked by uid 22791); 19 Dec 2011 11:52:11 -0000 X-SWARE-Spam-Status: No, hits=-2.9 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from localhost (HELO gcc.gnu.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 19 Dec 2011 11:51:56 +0000 From: "redi at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/51618] synchronous futures are slow Date: Mon, 19 Dec 2011 12:08:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: libstdc++ X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: redi at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2011-12/txt/msg02094.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51618 --- Comment #1 from Jonathan Wakely 2011-12-19 11:51:52 UTC --- Could you expand on what you mean by "no attached synchronization"? If a global future visible to all threads stores a deferred function then it still needs synchronization to ensure only one thread can invoke the deferred function and that other threads will wait for it to complete. std::async is not meant to be the fastest or most flexible solution, it's meant to be a simple way to exploit a limited amount of concurrency, without breaking the Kona compromise. Better solutions are suitable for TR2.