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From: les@chinet.chi.il.us (Leslie Mikesell)
Newsgroups: comp.lang.perl
Subject: Re: can we ever compile perl?
Message-ID: <1990Dec17.192346.9898@chinet.chi.il.us>
Date: 17 Dec 90 19:23:46 GMT
References: <1990Dec13.034336.21769@usenet@scion.CS.ORST.EDU> <93725765@bfmny0.BFM.COM> <1990Dec15.161911.27401@NCoast.ORG>
Organization: Chinet - Public Access UNIX
Lines: 34

In article <1990Dec15.161911.27401@NCoast.ORG> allbery@ncoast.ORG (Brandon S. Allbery KB8JRR) writes:
>As quoted from <93725765@bfmny0.BFM.COM> by tneff@bfmny0.BFM.COM (Tom Neff):
>+---------------
>|  2. For many of us, it would be enough to be able to make fast-loadable
>|     "Perl object files," i.e., write all data structures to disk after
>|     compilation & before execution.  The resulting "compiled scripts"
>|     would run faster because the parsing pass would be eliminated.
>|     Especially wonderful with large scripts!
>+---------------

>I mentioned this to Larry once; he pointed out that Perl's internal structures
>aren't particularly easy to save/restore in a portable way.  Of course, it
>might be possible to write(savefd, etext, sbrk(0) - etext), but this is also
>nonportable.

A reasonable solution is to not require the saved copy to be portable or
even explicitly saved.  Instead, add a  statement and/or command line
option to specify a directory to cache the parsed output allowing
the usual expansions of ~/, $HOME, etc. to give a choice between saving
in a public-writable directory or making a private copy for each user.
Then, if the directory exists and some quick checks establish that
the cached copy was written later than the script on a machine with
the same variable types, the parsing pass could be skipped.  Otherwise
a parsed copy would be saved in that directory (if permissions allow)
for the new run to use.  I think this would be a big help on machines
with slow disks and demand paged executables since it would likely
avoid the need to page in a lot of the perl program that would otherwise
be needed for the compile pass.  It might chew up some disk space,
but probably nowhere near to the extent that perl -u does, and this way
you still get the advantage of shared text when multiple copies of perl
are running.

Les Mikesell
  les@chinet.chi.il.us