Here's the diff http://cr.openjdk.java.net/~tonyp/8170910/webrev.0/
To setup an env to reproduce the issue, on a OSX machine with >= 10.12,
turn off services that register with mDNS. For my laptop, I had to turn off
iTunes and General System Preferences, disable "Allow Handoff between this
Mac and your iCloud services". You might have to restart. The reporter on
the ticket said to run `dns-sd -lo -B _services._dns-sd._udp local` to see
whether you have any running.
The file I used for exercising the behavior looks like this
import java.net.InetAddress;
public class Test {
public static void main(String[] args) throws Exception {
for (int i=0;i<4;i++){
long start = System.currentTimeMillis();
InetAddress localHost = InetAddress.getLocalHost();
System.out.println(localHost);
System.out.println(System.currentTimeMillis() - start);
}}}
The output I get on my laptop when I've set things up this way looks like
this on JDK 13 EA. The first call takes the full 5 seconds and subsequent
ones hit a cache.
nhoward.local/10.0.0.3
5044
nhoward.local/10.0.0.3
0
nhoward.local/10.0.0.3
0
nhoward.local/10.0.0.3
0
On JDK 8, each request takes 5 seconds. JDK 8's address lookup cache works
differently. It's localhost name cache expiry is 5 seconds.
On Thu, Apr 4, 2019 at 2:41 AM Michael McMahon <michael.x.mcma...@oracle.com>
wrote:
> Hi Nora,
>
> At first sight, the approach sounds reasonable to me. I'd like to see the
> patch
> and also do you have detailed instructions on how to reproduce the issue
> (the 5 second delay)?
>
> Thanks,
> Michael.
>
> On 03/04/2019, 17:46, Nora Howard wrote:
>
> I'd initially sent this to jdk-dev, but I was asked to move it to net-dev.
>
> On OSX 10.12 or later, when no mDNS services are registered, getaddrinfo
> fails on looking up localhost addresses[1]. The jdk’s current
> implementation falls back to getifaddrs after getaddrinfo fails[2]. When
> getaddrinfo fails in this way, it takes 5 seconds to fail [3]. This means
> that calls to InetAddress.getLocalHost() may take up to 5 seconds to run.
>
> I’d like to change the jdk’s behavior in this instance so that instead of
> falling back to calling getifaddrs after getaddrinfo fails, it instead
> calls getifaddrs first if we’re on OSX and the hostname is localhost’s.
>
> Doing this will eliminate the 5 second delay looking up localhost on
> machines with this network setup. When looking up non-localhost addresses,
> it’ll add a call to os:gethostname and a comparison.
>
> I’d like to get some feedback about whether this approach sounds
> reasonable, and some guidance about next steps. I’ve read the “how to
> contribute” page[4], and the “code review” guide[5].
>
> I’ve put together a patch that I’ve tested locally by turning off mDNS
> services on my local OSX machine and exercising the behavior. I’d like to
> submit patches that target dev trunk as well as the jdk 8 and 11 branches.
>
> References
>
> 1.
>
>> On a Macintosh running 10.12 or later, if there are no apps that have a
>> mDNS services registered (for instance, iTunes) and there are no services
>> selected in the Sharing System Preferences, then the getaddrinfo will fail.
>>
> (https://bugs.openjdk.java.net/browse/JDK-8170910)
>
> 2.
> http://hg.openjdk.java.net/jdk/jdk/file/cd3b7ad53265/src/java.base/unix/native/libnet/Inet6AddressImpl.c#l252
> http://hg.openjdk.java.net/jdk/jdk/file/cd3b7ad53265/src/java.base/unix/native/libnet/Inet4AddressImpl.c#l132
> (The lookupIfLocalhost function checks the passed hostname against
> os::get_host_name, and if they match, looks up via getifaddrs.)
>
> 3. This comment describes how to reproduce the issue. I’ve reproduced it
> locally on jdk 8, 11 and 13 ea.
> https://bugs.openjdk.java.net/browse/JDK-8170910?focusedCommentId=14038262&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-14038262
>
> 4. https://openjdk.java.net/contribute/
>
> 5. https://openjdk.java.net/guide/codeReview.html
>
> Thanks,
> --
> Nora
>
>
--
Nora
