Re: cgi-bin

[Jeff Sturm <jsturm at one-point dot com>]

On Sun, 14 Sep 2003, Erik Poupaert wrote:
> -rwxr-xr-x    1 erik     users     2221532 Sep 14 18:33 test.cgi
> -rwxr-xr-x    1 erik     users       84064 Sep 14 17:01 webmail.cgi
>
> Frustrating, isn't it?

Indeed.  Shared libraries are the way to go, but libgcj.so needs to be
more efficient.

The three important considerations in my mind are (in no particular
order):

1) startup time
2) memory footprint
3) runtime overhead

At the moment, libgcj.so loses on all three :-(

> Actually, webmail.cgi also revolves primarily around printf-ing to stdout
> (apparently cgi doesn't require much more).

CGI is extremely simple and requires no runtime support beyond env vars
and simple I/O.  (I once had an employer who created CGI executables in
FORTRAN.  They worked remarkably well!)

> > (RH9, maybe?)
> If they have it, they've been really quiet about it.

I grabbed prelink-0.2.0-18.i386.rpm from a RH9 mirror, and tried
prelinking a "Hello, World" executable.  The results are impressive!

before:

$ /usr/bin/time ./hello
Hello World
0.11user 0.01system 0:00.11elapsed 100%CPU (0avgtext+0avgdata 0maxresident)
0inputs+0outputs (1631major+158minor)pagefaults 0swaps

after:

$ /usr/bin/time ./hello
Hello World
0.02user 0.02system 0:00.03elapsed 108%CPU (0avgtext+0avgdata 0maxresident)
0inputs+0outputs (864major+193minor)pagefaults 0swaps

$ size hello
   text    data     bss     dec     hex filename
  89951     708       0   90659   16223 hello

Page faults are way down, and quite possibly memory usage as well.
There's still a lot of memory touched due to class registrations
at startup (easy to fix), and GC conservatively scanning all writable
data segments (harder).

Contrast with a static build:

$ size hello.static
   text    data     bss     dec     hex filename
2216037  365104  371400 2952541  2d0d5d hello.static

$ /usr/bin/time ./hello.static
Hello World
0.04user 0.01system 0:00.04elapsed 111%CPU (0avgtext+0avgdata 0maxresident)
0inputs+0outputs (659major+340minor)pagefaults 0swaps

The prelinked libgcj.so wins!

> # prelink test.cgi
> prelink: /usr/X11R6/bin/uil: Could not parse `/usr/X11R6/bin/uil: error while loading
> shared libraries: libMrm.so.3: cannot open shared object file: No such file or
> directory' prelink: /usr/X11R6/bin/xmanimate: Could not parse
> `/usr/X11R6/bin/xmanimate: error while loading shared libraries: libMrm.so.3: cannot

Hmm, odd that it would look in /usr/X11R6/bin at all.  Anyway, it looks as
though you need root privs to run prelink, since it wants to prelink all
dependent libs at once, including those in /lib.

Jeff