develooper Front page | perl.perl6.language | Postings from February 2001

Re: Garbage collection (was Re: JWZ on s/Java/Perl/)

Thread Previous | Thread Next
Jan Dubois
February 11, 2001 18:28
Re: Garbage collection (was Re: JWZ on s/Java/Perl/)
Message ID:
On Sun, 11 Feb 2001 21:11:09 -0500, "Bryan C. Warnock"
<> wrote:

>On Sunday 11 February 2001 19:08, Jan Dubois wrote:
>> However, I couldn't solve the problem of "deterministic destruction
>> behavior": Currently Perl will call DESTROY on any object as soon as the
>> last reference to it goes out of scope.  This becomes important if the
>> object own scarce external resources (e.g. file handles or database
>> connections) that are only freed during DESTROY.  Postponing DESTROY until
>> an indeterminate time in the future can lead to program failures due to
>> resource exhaustion.
>But doesn't resource exhaustion usually trigger garbage collection and 
>resource reallocation?  (Not that this addresses the remainder of your 

Not necessarily; you would have to implement it that way: When you try to
open a file and you don't succeed, you run the garbage collector and try
again.  But what happens in the case of XS code: some external library
tries to open a file and gets a failure.  How would it trigger a GC in the
Perl internals?  It wouldn't know a thing that it had been embedded in a
Perl app.

This scheme would only work if *all* resources including memory and
garbage collection are handled by the OS (or at least by a virtual machine
like JVM or .NET runtime).  But this still doesn't solve the destruction
order problem.


Thread Previous | Thread Next Perl Programming lists via nntp and http.
Comments to Ask Bjørn Hansen at | Group listing | About