On Fri, 20 Oct 2017, Ben Peart wrote:
> > While I am very much infavor of this change (I was not aware of the
> > --no-pretty option), I would like to see some statistics on that. Could
> > you measure the impact, please, and include the results in the commit
> > message?
> >
> > Ciao,
> > Johannes
> >
>
> I was also unaware of the --no-pretty option. I've tested this on Windows
> running version 4.9.0 of Watchman and verified that it does work correctly.
> I'm also curious if it produces any measurable difference in performance.
On a repository with ~160k files, the following test harness, which
requests all files inside the repository and parses that output:
--------------8<-----------
#!/usr/bin/perl
use strict;
use warnings;
use IPC::Open2;
my $pid = open2(\*CHLD_OUT, \*CHLD_IN, "watchman -j @ARGV")
or die "open2() failed: $!\n" .
"Falling back to scanning...\n";
my $query = qq|["query", "$ENV{PWD}", {}]|;
print CHLD_IN $query;
close CHLD_IN;
my $response = do {local $/; <CHLD_OUT>};
my $json_pkg;
eval {
require JSON::XS;
$json_pkg = "JSON::XS";
1;
} or do {
require JSON::PP;
$json_pkg = "JSON::PP";
};
my $o = $json_pkg->new->utf8->decode($response);
--------------8<-----------
...run with dumbbench[1], produces:
$ dumbbench -- ./test.pl
cmd: Ran 22 iterations (2 outliers).
cmd: Rounded run time per iteration: 5.240e+00 +/- 1.1e-02 (0.2%)
$ dumbbench -- ./test.pl --no-pretty
cmd: Ran 21 iterations (1 outliers).
cmd: Rounded run time per iteration: 4.866e+00 +/- 1.3e-02 (0.3%)
...so a modest 8% speedup. I note that those numbers are for a perl
with JSON::XS installed; without it installed, the runtime is so long
that I gave up waiting for it.
Anyways, I'll put that in the commit message in the re-roll.
- Alex
[1] https://metacpan.org/release/Dumbbench
