jmx-dev JDK-8031753: JMXServiceURL should not use getLocalHost or its usage should be enhanced (original) (raw)

Rob McKenna rob.mckenna at oracle.com
Mon Jan 27 16:50:23 PST 2014

Hi Maryan,

I'm cc'ing the jmx-dev folks. (and bcc'ing the jdk7u-dev alias) Hopefully they'll help move this conversation forward.

 -Rob

On 27/01/14 20:42, Maryan Bagnyuk (aka Maryan Bahnyuk) wrote:

Hello

As a reporter of JI-9009639 / JDK-8031753 <https://bugs.openjdk.java.net/browse/JDK-8031753> bug I'd like to inform you about the following.

Jaroslav Bachorík <https://bugs.openjdk.java.net/secure/ViewProfile.jspa?name=jbachorik>added a comment -2014-01-22 04:32 Not a regression. Oops. Sorry. Indeed I should have left this field blank. I'd understood the meaning of 'Regression' field incorrectly and had filled it in bug report by mistake. :( Jaroslav Bachorík <https://bugs.openjdk.java.net/secure/ViewProfile.jspa?name=jbachorik>added a comment -2014-01-22 04:32 If you insist on this issue being a regression, please, provide the exact version where the behavior was as expected. As I see all branches have this code for ages... [marbug at server1 jdk]$ pwd && hg annotate -f -a -u -d -n -c ./src/share/classes/javax/management/remote/JMXServiceURL.java | grep 'local = InetAddress.getLocalHost();' /home/marbug/cpp/jab/tmp/jdk6/jdk ohair 9 2d585507a41b Fri Jan 30 16:27:33 2009 -0800 src/share/classes/javax/management/remote/JMXServiceURL.java: local = InetAddress.getLocalHost(); [marbug at server1 jdk]$ pwd && hg annotate -r 0 -f -a -u -d -n -c ./src/share/classes/javax/management/remote/JMXServiceURL.java | grep 'local = InetAddress.getLocalHost();' /home/marbug/cpp/jab/tmp/jdk6/jdk duke 0 0c738a3e5791 Fri Jan 30 16:00:53 2009 -0800 src/share/classes/javax/management/remote/JMXServiceURL.java: local = InetAddress.getLocalHost(); [marbug at server1 jdk]$ cd ../../jdk7u/jdk/ [marbug at server1 jdk]$ pwd && hg annotate -f -a -u -d -n -c ./src/share/classes/javax/management/remote/JMXServiceURL.java | grep 'local = InetAddress.getLocalHost();' /home/marbug/cpp/jab/tmp/jdk7u/jdk duke 0 37a05a11f281 Sat Dec 01 00:00:00 2007 +0000 src/share/classes/javax/management/remote/JMXServiceURL.java: local = InetAddress.getLocalHost(); [marbug at server1 jdk]$ cd ../../jdk8/jdk/ [marbug at server1 jdk]$ pwd && hg annotate -f -a -u -d -n -c ./src/share/classes/javax/management/remote/JMXServiceURL.java | grep 'local = InetAddress.getLocalHost();' /home/marbug/cpp/jab/tmp/jdk8/jdk duke 0 37a05a11f281 Sat Dec 01 00:00:00 2007 +0000 src/share/classes/javax/management/remote/JMXServiceURL.java: local = InetAddress.getLocalHost(); [marbug at server1 jdk]$ cd ../../jdk9/jdk/ [marbug at server1 jdk]$ pwd && hg annotate -f -a -u -d -n -c ./src/share/classes/javax/management/remote/JMXServiceURL.java | grep 'local = InetAddress.getLocalHost();' /home/marbug/cpp/jab/tmp/jdk9/jdk duke 0 37a05a11f281 Sat Dec 01 00:00:00 2007 +0000 src/share/classes/javax/management/remote/JMXServiceURL.java: local = InetAddress.getLocalHost(); So the expected behaviour is just my conslusion/suggestion. Jaroslav Bachorík <https://bugs.openjdk.java.net/secure/ViewProfile.jspa?name=jbachorik>added a comment -2014-01-22 04:32 I would argue that workaround should be L - it is easy to fix the hostname and the solution is persistent. If the reporter can describe a situation where fixing the hostname is not an option the workaround should stay at M. As I understand you suggest to fix hostname and/or an appropriate record in /etc/hosts (under Linux). Everyone suggest this in 'google search'... :( But IMHO it's not an option because: 1) As far as I know no one must have root access to run programs with JMX agent. 1.1) With this suggestion everyone must have root access (because only root or sudo-ed user may change hostname and/or /etc/hosts) 1.1.1) What if someone do not have root access to his PC (some companies do not allow to install additional software without their permissions)? 1.1.2) Will you add the appropriate note to the 'Install' section in Java manual/documentation? Or should everyone just google this exception to find the fix of this issue? :) 2) Indeed Agent does not use hostname or it's IP to run JMX server (please take a look at my original post) 2.1) If Agent does not use it (i.e. hostname/IP) then why should it depend on it? 3) Why should I change hostname if other services work correctly without it? 3.1) OS ignores that hostname can't be resolved to some IP and is started successfully 3.2) Apache does so too (because it listens on 0.0.0.0 in IPv4) 3.3) SSH server as well ... 3.4) etc., etc., etc. 3.5) but java throws an exception IMHO this does not follow the 'general' scheme ;) 4) How about JMX client (i.e. "Connecting to the JMX Agent Programmatically ")? http://docs.oracle.com/javase/7/docs/technotes/guides/management/agent.html#gdevg STR: 4.1) server1 is behind NAT (example 1: on my VM, example 2: in Amazon Cloud) 4.2) port mapping is configured from external IP to the local one (i.e. there is only local network IP on interface) 4.3) I have associated my hostname (for instance, server1.customer22.example.com) with 127.0.0.1 ( Is it a good idea to do this in Amazon Cloud? IMHO no. ;) ) 4.4) I start a program (Cassandra, Program4STR, etc.) via Agent 4.5) if someone will change a record for server1.customer22.example.com to the correct external IP then why should agent connect to external IP instead of local one? :) 4.5.1) if I run client on server1 then it's enough to connect to localhost instead of external IP. Isn't it? 4.5.2) if I start client on another PC then in any case I'll pass the needed value in 'host' parameter to JMXServiceURL(...) 5) etc., etc., etc. (see examples from my original post and imagine how client will connect to JMX server in each case) Indeed the decision is 'up to you' but IMHO making the suggested change will simplify everything, save time of many people (they will not need to change hostname and/or /etc/hosts), google will deprecate search of ' Error: Exception thrown by the agent : java.net.MalformedURLException: Local host name unknown:' string and at least several developers and system administrators will be happy not to take care about hostname ... At least for Java and programs which use Agent ;) Thanks

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