On May 21, 5:38 pm, Dustin <dsalli...@gmail.com> wrote:
..
>
> I can't imagine why it wouldn't be worse. On each iteration, you
> compile a SQL query then block on network activity 20 times in the
> memcached case. You're doing almost the entire SQLite workload in the
> memcached case and then mixing in a gang of network round trips.
>
> In the SQLite case, you should've expected a performance gain since
> you're compiling queries less frequently than you did in the previous
> version.
>
> memcached is a network service. You'd never structure code such
> that the inner loop of your program requires a full round trip over
> the network. Perform a single get for all of the keys you want and if
> you miss any, compile the query at that time, backfill them, and fill
> in the holes.
Nice. I changed the code to
sub {
my $sth = $dbh->prepare($sql);
my @res = ();
my $hashref = $memd->get_multi(@ids);
while (my ($id, $str) = each %$hashref) {
unless ($str) {
$sth->execute($id);
($str) = $sth->fetchrow_array;
$memd->set($id, $str);
}
push @res, [$_, $str];
}
out(@res);
}
and now I get
Benchmark: timing 10000 iterations of query_dbh, query_mem...
query_dbh: 6 wallclock secs ( 3.28 usr + 1.03 sys = 4.31 CPU) @
2320.19/s (n=10000)
query_mem: 10 wallclock secs ( 6.57 usr + 1.45 sys = 8.02 CPU) @
1246.88/s (n=10000)
instead of
Benchmark: timing 10000 iterations of query_dbh, query_mem...
query_dbh: 6 wallclock secs ( 3.29 usr + 1.03 sys = 4.32 CPU) @
2314.81/s (n=10000)
query_mem: 54 wallclock secs (30.02 usr + 8.24 sys = 38.26 CPU) @
261.37/s (n=10000)
an almost 5 times improvement.
