From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: fac41,15edb893ef79e231 X-Google-Attributes: gidfac41,public X-Google-Thread: f4fd2,23202754c9ce78dd X-Google-Attributes: gidf4fd2,public X-Google-Thread: 103376,15edb893ef79e231 X-Google-Attributes: gid103376,public X-Google-Thread: 114809,15edb893ef79e231 X-Google-Attributes: gid114809,public X-Google-ArrivalTime: 2002-01-22 14:09:59 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!cyclone.bc.net!newsfeed.direct.ca!look.ca!wn1feed!worldnet.att.net!135.173.83.71!wnfilter1!worldnet-localpost!bgtnsc05-news.ops.worldnet.att.net.POSTED!not-for-mail Message-ID: <3C4DE336.3080102@worldnet.att.net> From: Jim Rogers User-Agent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:0.9.4) Gecko/20011128 Netscape6/6.2.1 X-Accept-Language: en-us MIME-Version: 1.0 Newsgroups: comp.lang.lisp,comp.lang.ada,comp.lang.eiffel,comp.lang.smalltalk Subject: Re: True faiths ( was Re: The true faith ) References: <%njZ7.279$iR.150960@news3.calgary.shaw.ca> <3c36fbc5_10@news.newsgroups.com> <4idg3u40ermnp682n6igc5gudp7hajkea9@4ax.com> <76be8851.0201101909.9db0718@posting.google.com> <9jtu3u8cq92b05j47uat3412tok6hqu1ki@4ax.com> <3C3F8689.377A9F0F@brising.com> <3219936759616091@naggum.net> <3C483CE7.D61D1BF@removeme.gst.com> <7302e4fa4a.simonwillcocks@RiscPC.enterprise.net> <3C4D9B03.60803@mail.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 22 Jan 2002 22:09:58 GMT NNTP-Posting-Host: 12.86.33.31 X-Complaints-To: abuse@worldnet.att.net X-Trace: bgtnsc05-news.ops.worldnet.att.net 1011737398 12.86.33.31 (Tue, 22 Jan 2002 22:09:58 GMT) NNTP-Posting-Date: Tue, 22 Jan 2002 22:09:58 GMT Organization: AT&T Worldnet Xref: archiver1.google.com comp.lang.lisp:25010 comp.lang.ada:19199 comp.lang.eiffel:5501 comp.lang.smalltalk:18480 Date: 2002-01-22T22:09:58+00:00 List-Id: Bruce Hoult wrote: > Garbage collection has a *lot* to do with this problem! > > A large proportion of assignments in languages such as C++ are done > merely in order to resolve the question of who owns an object and who is > responsible for eventually deleting it. > > With GC available, objects are seldom copied with pointers to them being > passed around instead. You don't care who "owns" the object, because it > just magically goes away when all the pointers to it get forgotten. Copying pointers and using GC or even reference counting is a very nice solution for single threaded applications. It becomes a very messy solution for multi-threaded applications. Now all those copied pointers need to be protected from inappropriate simultaneous access by several threads. In threaded applications GC solves no concurrency issues, but it does complicate them. How can a semaphore be "held" by only one thread if only one instance exists, and all threads hold a pointer to that instance? How can you keep one thread from consuming all the free store or "heap"? Obviously there are answers to all those questions. Unfortunately, those answers a generally pretty messy unless someone has designed your GC solution with concurrency in mind. Jim Rogers Colorado Springs, Colorado USA