我有兴趣并行执行多个数据库操作。我玩过Perl Parallel :: ForkManager,但还没有用过任何数据库。我已经读过这个数据库连接not supported very well。有没有人有这方面的经验?
作为一个例子,我可能会产生一个系统调用(它使DBI工作)不是原始代码,即
#!/opt/local/bin/perl -w
use strict;
use Parallel::ForkManager;
$| = 1;
my $max_procs = 10;
my $pm = new Parallel::ForkManager($max_procs);
for (my $var = 0; $var <= 10; $var++) {
my $pid = $pm->start('proc'.$var) and next;
sleep ( 2 );
system( "./DBworker.pl $var" );
$pm->finish(0);
}
print "Waiting for child procs\n";
$pm->wait_all_children;
print "complete!\n";
答案 0 :(得分:9)
如果其他程序正在完成工作,则fork
没有危险。当您打开与数据库的连接然后fork时,会出现危险。孩子不能重复使用父母的联系;但是,看看DBIx::Connector
,它会处理fork
之后您需要做的事情,并且运行多个程序通常不是正确的答案。
#!/usr/bin/perl
use strict;
use warnings;
use DBIx::Connector;
use Parallel::ForkManager;
my $dsn = "dbi:SQLite:dbname=foo.db";
my $user = "";
my $pass = "";
my $conn = DBIx::Connector->new($dsn, $user, $pass,
{
AutoCommit => 0,
PrintError => 0,
RaiseError => 1,
ChopBlanks => 1,
FetchHashKeyName => 'NAME_lc',
}
);
END { unlink "foo.db" }
#setup table
$conn->run(fixup => sub {
my $dbh = $_;
$dbh->do("create table foo ( id integer, name char(35) )");
my $sth = $dbh->prepare("insert into foo (id, name) values (?, ?)");
while (<DATA>) {
chomp;
$sth->execute(split /,/);
}
});
my $pm = Parallel::ForkManager->new(3);
my $sth = $conn->dbh->prepare("select * from foo where id = ?");
for my $id (1 .. 3) {
next if $pm->start;
$sth->execute($id);
while (my $row = $sth->fetchrow_hashref) {
print "$id saw $row->{id} => $row->{name}\n";
}
$pm->finish;
}
$pm->wait_all_children;
print "done\n";
__DATA__
1,foo
2,bar
3,baz