jmx-dev JDK-8031753: JMXServiceURL should not use getLocalHost or its usage should be enhanced
Maryan Bagnyuk (aka Maryan Bahnyuk)
marbuga at gmail.com
Tue Feb 4 23:32:25 PST 2014
Hello
I'd like to note that fixing hostname requires additional development
(as a separate module/script/program) or support (by system
administrator, support staff, etc.).
Making the suggested (from my side) fix of JMXServiceURL.java file
should resolve current issue is the
fastest/easiest/most_clear/most_correct way (indeed IMHO).
I am ready to prepare the needed patch and tests (for 7, 8, 9 versions
of jdk).
Could you please let me know if you are ready to accept following this
way (replace getLocalHost by getByName) or are you not interested in
such approach and everyone have to fix hostname?
Thanks
P.S. Or should I send the patch and you'll make a decision after
reviewing it?
On 02/04/2014 09:20 PM, Maryan Bagnyuk (aka Maryan Bahnyuk) wrote:
> Hello.
>
> Do I understand correctly that my conclusions regarding "fixing the
> hostname is not an option" are incorrect?
>
> Or may/should it be fixed in the following way:
>
> try {
> - local = InetAddress.getLocalHost();
> + local = InetAddress.getByName("localhost");
> } catch (UnknownHostException e) {
>
> Sincerely, Maryan
>
> P.S. Sorry if my previous message was impolite or jokes were too plain
>
> On 01/28/2014 02:50 AM, Rob McKenna wrote:
>> 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
>>>
>>
>
--
Sincerely,
Maryan Bagnyuk (aka Maryan Bahnyuk)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.openjdk.java.net/pipermail/jmx-dev/attachments/20140205/0d7762b0/attachment.html
More information about the jmx-dev
mailing list