Default configuration of open files in Wildfly

[arkadyz]

Hello,

I am getting following lines in my log files:

2017-01-11 02:32:46,940 WARN  [org.jboss.as.warn.fd-limit] JBAS015972: The operating system has limited the number of open files to 3072 for this process; a value of at least 4096 is recommended

...

2017-01-11 02:26:21 [ServerService Thread Pool -- 34] WARN wildfly.extension.io  - WFLYIO005: Your system is configured with 3072 file descriptors, but your current application server configuration will require a minimum of 3192 (and probably more than that); attempting to adjust, however you should expect stability problems unless you increase this number

My question is:

From where wildfly take actual file descriptors configuration 4096 & 3192?? I didn't find it in configuration files.

We are using Wildfly 8.2.0

Thanks in advance.

[mayerw01]

The MaxFileDescriptorCount may be checked via JConsole (MBeans -> java.lang -> Operating System -> Attributes)

[arkadyz]

I have no GUI packages installed on my machine. May be you can paste here lines of java code Wildfly run to get this info or to lead me where to download relevant source code ?

[ctomc]

Arkady Zelekman wrote:

I have no GUI packages installed on my machine. May be you can paste here lines of java code Wildfly run to get this info or to lead me where to download relevant source code ?

You can do simple mbean lookup for this. that is what io subsystem is doing. see wildfly-core/WorkerAdd.java at 2.x · wildfly/wildfly-core · GitHub

[mayerw01]

The Java docs provide more details (Standard MBeans (The Java™ Tutorials > Java Management Extensions (JMX) > Introducing MBeans) )

But such a program may be very simple like:

package source;

import java.lang.management.ManagementFactory;

import javax.management.MBeanServer;

import javax.management.ObjectName;

public class TestMbean {

    public static void main(String[] args) throws Exception {

        ObjectName name = new ObjectName("java.lang:type=OperatingSystem");

        MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();

        String attribute = "MaxFileDescriptorCount";

        System.out.println(attribute + " = "

                + Long.parseLong(mbs.getAttribute(name, attribute).toString())) ;

    }

}

[arkadyz]

Wolfgang, thanks

If I understand correctly from here: OperatingSystemMXBean (Java Platform SE 7 ), this message bean is published by JVM of Wildfly during start.

So, the value of MaxFileDescriptorCount is calculated and by JVM of Wildfly.

Am I understand correctly ?

Thanks.

[arkadyz]

I am also would like to know how this value is calculated. Is it in Wildfly sources or it is in JDK ?

[mayerw01]

Neither nor. This value shows the hard limits set in your operating system. In Linux you may check the max number of open files via 'prlimit -n'. This shows as well the hard as the soft limits. But you can also use the command 'ulimit -n' to show the soft and 'ulimit -Hn' to show the hard limits. In the man pages you may find more details regarding these commands.

[abhinav.gupta01]

I assume you want to increase limits.. This properties are not at wildlfy level as pointed already above.

Have a look in below files on you linux box :

1. In /etc/security/limits.conf file add

<usernmae> hard nofile <limitvalue>

<username> soft nofile <limitvalue>
  where <username>is the user (login user)

2. In /etc/sysctl.conf file add

fs.file-max = 68157440

PS : This will need restart and if you dont see this property , you can add new.

[arkadyz]

'prlimit -n' doesn't work in Red Hat linux. What is the right command in Reh Hat linux ?

Thanks,

Arkady