Error opening matlabpool

I'm receiving the following error when attempting to issue a matlabpool open command:

Error using matlabpool (line 126) Java exception occurred: java.net.UnknownHostException: bob: bob at java.net.InetAddress.getLocalHost(Unknown Source)

Let's assume for the moment that the name of the Linux box running Matlab is bob. It's running Fedora with a current Java install (1.6.0_22) and the most recent version of the Parallel Computing Toolbox.

I get a similar error when attempting to query the current computer name using java.net.InetAddress.getLocalHost.getHostName. Fiddling with the hostname in dctconfig or pctconfig does not produce any useful results.

I'm sure this is just a newb java-matlab communication problem. Any tips out there?

[Thomas]

Are you running matlabpool on a local configuration (local machine) or do you have a parallel configuration for a cluster?

[Mark]

Local.

Answer 1

[Titus Edelhofer]

Could you try to add localhost with 127.0.0.1 to your /etc/hosts file?

Titus

[Mark]

It's already there. I also get an error with java.net.InetAddress.getLocalHost.getHostName.

[Titus Edelhofer]

Hi Mark,

in a shell (no MATLAB): what does "hostname -a" give?

Titus

[Mark]

hostname: Name or service not known

[Titus Edelhofer]

Hi Mark, this might explain your problems. hostname is usually /etc/hostname. Either etc is not in your path or you managed somehow to delete the program... Try to re-install (or add the folder /etc or whereever you find the program) to your path and then start MATLAB again.

Titus

[Mark]

But, the etc/hosts file does seem to be the key. I duplicated the 127.0.0.1 line but changed the host information, so the first two lines now read:

127.0.0.1 localhost.localdomain localhost

127.0.0.1 bob.localdomain bob

and matlabpool open works just fine. Thanks to everyone for the tips for getting me headed in the right direction.

[Titus Edelhofer]

Hi Mark,

I'm glad to hear it's running!

Titus

[Clayton]

I also had this problem (running linux RHEL 6 and Matlab R2014a).

>> parpool('local')
Error using parpool (line 99)
Java exception occurred:
java.net.UnknownHostException: EMS-GJDZW12: EMS-GJDZW12: Name or service not
known
  at java.net.InetAddress.getLocalHost(Unknown Source)
Caused by: java.net.UnknownHostException: EMS-GJDZW12: Name or service not known
  at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
  at java.net.InetAddress$1.lookupAllHostAddr(Unknown Source)
  at java.net.InetAddress.getAddressesFromNameService(Unknown Source)
  ... 1 more

I tested by pinging my hostname and localhost. Only the latter worked.

[clayton@myMachine ~]$ ping myMachine
ping: unknown host myMachine

[clayton@myMachine ~]$ ping localhost
PING localhost (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.048 ms
64 bytes from localhost (127.0.0.1): icmp_seq=2 ttl=64 time=0.029 ms

Then added third line to my /etc/hosts file so it looks like:

127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
127.0.0.1   myMachine.localdomain myMachine

And then I could ping my hostname and start parpool with no problems.

[clayton@myMachine ~]$ ping myMachine
PING myMachine.localdomain (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.035 ms
64 bytes from localhost (127.0.0.1): icmp_seq=2 ttl=64 time=0.037 ms
64 bytes from localhost (127.0.0.1): icmp_seq=3 ttl=64 time=0.036 ms

Answer 2

[Michal Kvasnicka]

Same error on openSUSE 12.1 with Matlab R2011b.

Any hints???

Answer 3

[Daniel Shub]

Works fine for me on r2011a and Arch:

>> matlabpool open
Starting matlabpool using the 'local' configuration ... connected to 8 labs.

MATLAB Version 7.12.0.635 (R2011a) Operating System: Linux 3.1.0-4-ARCH #1 SMP PREEMPT Mon Nov 7 22:47:18 CET 2011 x86_64 Java VM Version: Java 1.6.0_17-b04 with Sun Microsystems Inc. Java HotSpot™ 64-Bit Server VM mixed mode

I also get a meaningful result with:

java.net.InetAddress.getLocalHost.getHostName

I do have 127.0.0.1 in my /etc/hosts file.

Answer 4

[Thomas]

Can you try validating your local parallel configuration.

Parallel > Manage Configuration> select 'local'> Start Validation.

What results do you get?

Your output should be;

Validation Details

Configuration: "local"
Type: local

--------------------------------------
Stage: Find Resource

Status: Passed
Description:  Validation passed

Command Line Output: (none)

--------------------------------------
--------------------------------------
Stage: Distributed Job

Status: Passed
Description:  Validation passed

Command Line Output: (none)

--------------------------------------
--------------------------------------
Stage: Parallel Job

Status: Passed
Description:  Validation passed

Command Line Output: (none)

--------------------------------------
--------------------------------------
Stage: Matlabpool

Status: Passed
Description:  Validation passed

Command Line Output:
Starting matlabpool using the 'local' configuration ... Checking parallel job status.
Checking parallel job status.
Checking parallel job status.
Received a socket connection.
Received a socket connection.
Received a socket connection.
Received a socket connection.
Received a socket connection.
Received a socket connection.
Received a socket connection.
Received a socket connection.
connected to 8 labs.Sending a stop signal to all the labs ... stopped.
Did not find any pre-existing parallel jobs created by matlabpool.

[Mark]

Fails on the same Java call... I get:

Validation Details

Configuration: "local"

Type: local

--------------------------------------

Stage: Find Resource

Status: Failed

Description: An otherwise unexpected error is encountered.

Command Line Output: (none)

Error Report:

Java exception occurred:

java.net.UnknownHostException: bob: bob

at java.net.InetAddress.getLocalHost(Unknown Source)

Error in distcomp.localscheduler (line 57)

procInfo = struct('pid', pid, 'pidname', dct_psname(pid), ...

Error in distcomp/createObjectsFromProxies (line 46)

obj = constructor(proxies(i));

Error in findResource>iCreateFileBasedScheduler (line 393)

out = distcomp.createObjectsFromProxies(proxy, uddConstructor, distcomp.getdistcompobjectroot);

Error in findResource>iFindScheduler (line 345)

out = iCreateFileBasedScheduler(type);

Error in findResource (line 172)

[out, props, pvals] = iFindScheduler(props, pvals, configurationNameSpecified);

Error in validateConfig>@()findResource('scheduler','configuration',config) (line 80)

findResourceFcn = @() findResource('scheduler', 'configuration', config); %#ok<NASGU> - used in evalc

Error in validateConfig>doValidate (line 81)

[cmdWinOutput, scheduler] = evalc('findResourceFcn()');

Error in validateConfig (line 54)

doValidate(validationClient, config, timeout);

[output for other stages deleted as they are all skipped]

[Thomas]

This error means that it cannot find the ip address or hostname of the machine:

what output does the following command provide?

system('hostname')

[Titus Edelhofer]

Hi Thomas,

seems either not on the path or not installed, see Marks comment to my answer above ...

[Mark]

Actually hostname by itself was working fine, but without the additional line in /etc/hosts hostname -a was failing. In any case adding the line in etc/hosts has solved this problem for me -- hopefully it will do the same for others. Thanks to both of you for the help.

Answer 5

[Josh]

For me, running openSUSE, I fixed the issue in Yast->Network Settings->Hostname/DNS. Make sure the "Assign Hostname to Loopback IP" is checked. That did it for me.

Answer 6

[Gerald]

I'm receiving the following error when attempting to issue a parpool open command in Matlab 2014b based on Debian system

Error using parpool (line 99) Java exception occurred: java.net.UnknownHostException: (none): (none): Name or service not known at java.net.InetAddress.getLocalHost(Unknown Source) at com.mathworks.jmi.NativeMatlab.SendMatlabMessage(Native Method) at com.mathworks.jmi.NativeMatlab.sendMatlabMessage(NativeMatlab.java:266) at com.mathworks.jmi.MatlabLooper.sendMatlabMessage(MatlabLooper.java:120) at com.mathworks.jmi.Matlab.mtFevalConsoleOutput(Matlab.java:1690) at com.mathworks.jmi.MatlabWorker.feval(MatlabWorker.java:195) at com.mathworks.toolbox.distcomp.ui.desk.ParallelStatusIndicator$ParallelStatusIndicatorUI$9$1.runOnMatlabThread(ParallelStatusIndicator.java:772) at com.mathworks.jmi.MatlabWorker$2.run(MatlabWorker.java:79) at com.mathworks.jmi.NativeMatlab.dispatchMTRequests(NativeMatlab.java:475) Caused by: java.net.UnknownHostException: (none): Name or service not known at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method) at java.net.InetAddress$1.lookupAllHostAddr(Unknown Source) at java.net.InetAddress.getAddressesFromNameService(Unknown Source) ... 9 more

Error in parallel.internal.ui.PoolHelper.startPool (line 11) parpool();

I already changed the hosts files as described above and can ping localhost and myMachine. However, parpool still does not work.

Any tips out there?