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
<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
