Article View: borland.public.jbuilder.java.api
Article #280Re: Hashtable keys
From: Petar Banicevic
Date: Sat, 27 Mar 2004 21:51
Date: Sat, 27 Mar 2004 21:51
44 lines
2445 bytes
2445 bytes
Hi, 1) You can hear that GC uses reference counting, or mark and sweep mechanism to sweep the heap, but it is up to the JVM implementation and you can't be sure how it works. The only thing you can trust is the following definition: 2) Object is elibible for garbage collection when no live thread can access it (including main thread!). It is incorrect to say that the object is eligible for garbage collection when it has no references (case: islands of insolation) 3) Islands of insolation is the case when you have several objects cross-refering and none of them is reachable by any live thread. Then these two objects are considered to be "islands of objects". GC will discover them and sweep them out. Your case with hashtable is case 3. You need to know whether any of objects can be reached by living thread, including the Hashtable. If there is no references to Hashtable and objects in Hashtable from live threads, then GC will sweep them. If there are refs to Hashtable they won't be sweeped. If there are refs to objects but not to Hashtable, then only hashtable would be sweeped. HTH. Regards. "Jason Purcell" <purcelj@telkom.co.za> wrote in message news:406030e5$2@newsgroups.borland.com... > > I have a Hashtable where the keys are Connection objects, > and the values are Boolean objects. > > My question is: Will the Connection objects ever be > garbage-collected while the Hashtable is still valid > and being used? > > By extension, are keys in a Hashtable ever automatically > removed? > > Jason.
Technical Details
Message-ID:
<4065f73b@newsgroups.borland.com>Path:
arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!news.glorb.com!newsfeed00.sul.t-online.de!newsfeed01.sul.t-online.de!t-online.de!newsgroups.borland.com!not-for-mailReferences:
<406030e5$2@newsgroups.borland.com>Show Full Headers
Complete Article Headers
X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 1089d0,54684b980608b0f4 X-Google-Attributes: gid1089d0,public X-Google-ArrivalTime: 2004-03-27 14:09:27 PST From: "Petar Banicevic" <petar2@kupi.biz> Newsgroups: borland.public.jbuilder.java.api References: <406030e5$2@newsgroups.borland.com> Subject: Re: Hashtable keys Date: Sat, 27 Mar 2004 22:51:44 +0100 Lines: 46 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 NNTP-Posting-Host: 193.198.139.66 Message-ID: <4065f73b@newsgroups.borland.com> X-Trace: newsgroups.borland.com 1080424251 193.198.139.66 (27 Mar 2004 13:50:51 -0800) Path: arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!news.glorb.com!newsfeed00.sul.t-online.de!newsfeed01.sul.t-online.de!t-online.de!newsgroups.borland.com!not-for-mail