Re: BUG #5066: plperl issues with perl_destruct() and END blocks

From: Tim Bunce <Tim(dot)Bunce(at)pobox(dot)com>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: Tim Bunce <Tim(dot)Bunce(at)pobox(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #5066: plperl issues with perl_destruct() and END blocks
Date: 2009-09-21 10:05:43
Message-ID: 20090921100543.GA961@timac.local
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On Sun, Sep 20, 2009 at 10:00:01PM -0400, Alvaro Herrera wrote:
> There's a definitional problem here however. When should we call the
> destructor? My impression is that it should happen when the calling
> query terminates, not when the backend shuts down. I'm sure this will
> cause other issues -- for example %_SHARED will be destroyed way too
> early.

The perlmod man page says:

An "END" code block is executed as late as possible, that is, after
perl has finished running the program and just before the interpreter
is being exited, even if it is exiting as a result of a die() function.
[...]
Note that "END" code blocks are not executed at the end of a string
"eval()": if any "END" code blocks are created in a string "eval()",
they will be executed just as any other "END" code block of that pack‐
age in LIFO order just before the interpreter is being exited.

so executing at the end of query, a transaction, or a session would be
wrong. They should execute "as late as possible", "just before the
interpreter being exited".

Tim.

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