Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!news.musoftware.de!wum.musoftware.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Ian Collins Newsgroups: comp.programming Subject: Re: reference count size Date: Sat, 09 Jun 2012 21:43:27 +1200 Lines: 21 Message-ID: References: <233b32fd-bdfc-4ffb-a9da-320abb11c07d@googlegroups.com> <05l1t7tvick0mve6on4fekg5hvr373u93l@4ax.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Trace: individual.net vk2gMExNxah3pFEZumj/vAub8iKIpoOSi4Za6hWJah88fSjpPAWF/qPXMJtm4xX8pn Cancel-Lock: sha1:uKVcQ25jt3U4JLn7aID6rHbJuzU= User-Agent: Mozilla/5.0 (X11; SunOS i86pc; rv:12.0) Gecko/20120423 Thunderbird/12.0 In-Reply-To: Xref: csiph.com comp.programming:1760 On 06/ 9/12 09:29 PM, Chris Uppal wrote: > Robert Wessel wrote: > >> 64 bit systems are all over the place. I've seen 32, 40, 48 and 64 >> bit reference counts, although 32 may be the most common for now (in >> both the 48 and 64 bit cases some bits nominally in the count field >> were repurposed). > > Interested to know where you've seen these choices ? > > To my knowledge, such as it is, reference-counting has all but died out. The > exceptions being more-or-less ad-hoc solutions to problems requiring GC in > languages which don't have it (e.g. COM); highly specialised domains (such as > Unix I-Nodes); and optimisations in "real" GC (which use only one or two bits + > saturation). Reference counting isn't only used in GC. C++ smart pointers (such as std::shared_ptr) are one common example. -- Ian Collins