我试图实现一个不可靠的服务器的请求。该请求是一个很好的,但我的Perl脚本不能100%成功完成。问题在于服务器偶尔会发生死锁(我们试图弄清楚原因),并且请求永远不会成功。由于服务器认为它是活动的,因此它保持套接字连接打开,因此LWP :: UserAgent的超时值对我们来说没有好处。对请求执行绝对超时的最佳方式是什么?LWP :: UserAgent请求方法的真正超时
仅供参考,这不是DNS问题。这个僵局与大量更新同时触发我们的Postgres数据库有关。出于测试目的,我们已经在服务器响应处理程序中放了一段时间(1){}行。
目前,代码看起来像这样:
my $ua = LWP::UserAgent->new;
ua->timeout(5); $ua->cookie_jar({});
my $req = HTTP::Request->new(POST => "http://$host:$port/auth/login");
$req->content_type('application/x-www-form-urlencoded');
$req->content("login[user]=$username&login[password]=$password");
# This line never returns
$res = $ua->request($req);
我一直在使用信号触发超时尝试过,但似乎并没有工作。
eval {
local $SIG{ALRM} = sub { die "alarm\n" };
alarm(1);
$res = $ua->request($req);
alarm(0);
};
# This never runs
print "here\n";
最终的答案,我将使用脱机被提出的一个人,但我会在这里提到它。出于某种原因,SigAction可以工作,而$ SIG(ALRM)则不可以。仍然不知道为什么,但这已经过测试,以工作。这里有两个工作版本:
# Takes a LWP::UserAgent, and a HTTP::Request, returns a HTTP::Request
sub ua_request_with_timeout {
my $ua = $_[0];
my $req = $_[1];
# Get whatever timeout is set for LWP and use that to
# enforce a maximum timeout per request in case of server
# deadlock. (This has happened.)
use Sys::SigAction qw(timeout_call);
our $res = undef;
if(timeout_call(5, sub {$res = $ua->request($req);})) {
return HTTP::Response->new(408); #408 is the HTTP timeout
} else {
return $res;
}
}
sub ua_request_with_timeout2 {
print "ua_request_with_timeout\n";
my $ua = $_[0];
my $req = $_[1];
# Get whatever timeout is set for LWP and use that to
# enforce a maximum timeout per request in case of server
# deadlock. (This has happened.)
my $timeout_for_client = $ua->timeout() - 2;
our $socket_has_timedout = 0;
use POSIX;
sigaction SIGALRM, new POSIX::SigAction(
sub {
$socket_has_timedout = 1;
die "alarm timeout";
}
) or die "Error setting SIGALRM handler: $!\n";
my $res = undef;
eval {
alarm ($timeout_for_client);
$res = $ua->request($req);
alarm(0);
};
if ($socket_has_timedout) {
return HTTP::Response->new(408); #408 is the HTTP timeout
} else {
return $res;
}
}
的可能的复制[如何执行在Perl明确超时?](http://stackoverflow.com/questions/15899855/how-to-enforce-a -definite-timeout-in-perl) – sixtyfootersdude 2016-02-24 22:51:45