JniPing vs. JnaPing

November 28, 2024 6 min read Monitoring How-To OpenNMS Ronny Trommer

As described in the previous article we have build an OpenNMS Horizon Core component from source. If you don’t do anything else, it will uses an ICMP implementation using Java Native Access (JNA). The big benefit here, it’s all Java and supports IPv4 and IPv6. You also don’t need additional permissions on your Linux system such as net.ipv4.ping_group_range and SELinux. It makes it perfect for local development and also if you want to run OpenNMS on exotic architectures where you can’t easily compile or build the JNI equivalent written in C from the source code. The downside it comes with some overhead for each ICMP service test. You can see the effect on the latency measurements, especially on very fast responding IP addresses, such as the local loopack interface.

Jni6Pinger measuring latency against the same local IPv6 address

The image gives you a similar time frame testing the ICMP response times using the JNA implementation compared with the measured response times from the JNI implementation.

💁‍♀️ In production environments, it would be fair to say to use the JNI 6 pinger to get a) faster release of Pollerd threads with large ICMP service test workloads and b) more accuracy for latency measurements. This will also be valid if StrafePing for monitoring Jitter is used.

In this session we want to go through the process compiling and building the JICMP and JICMP6 libraries from source code on Rocky Linux 9.

Requirements

Working directory is the home directory of a user who can do administrative tasks with sudo , in this case a user rocky in /home/rocky
You need git, internet access to GitHub, and access to public Rock Linux packages
For this session, I’m using the installed OpenNMS Horizon Core instance from the OpenNMS - Auf die harte Tour article which is using the JnaPinger by default
The configuration scripts are generated with autoconf and libtool (sudo dnf install -y autoconf libtool)
☢️ JICMP and JICMP6 use javah to build the C header and source files from Java classes. javah is removed with OpenJDK 10. You have to install a JDK 8 Development Kit to make it work (dnf install -y java-1.8.0-openjdk-devel).

Build JICMP

The JICMP library, is implementing ICMP for IPv4 only. It will be referenced in Pollerd as org.opennms.netmgt.icmp.jni.JniPinger.

git clone https://github.com/opennms/jicmp

Generate the configure scripts

cd jicmp
autoreconf -fvi

Configure the build environment. The configure script will pick automatically Java 8 even when you have more than one JDK installed.

💁‍♀️ The options --with-java=JAVA_HOME and --with-jvm-arch=(32|64) can be applied to the ./configure script in case you have a very specific build environment.

./configure

Compile and install the JAR and shared object library with

make && sudo make install

The JAR and the library will be installed to

/usr/local/share/java/jicmp.jar
/usr/local/lib/libjicmp.so
/usr/local/lib/libjicmp.la

Build JICMP6

The JICMP library, is implementing ICMP for IPv4 and IPv6. It will be referenced in Pollerd as org.opennms.netmgt.icmp.jni6.Jni6Pinger. The installation procedure is exactly the same as for JICMP.

git clone https://github.com/opennms/jicmp6

Generate the configure scripts

cd jicmp6
autoreconf -fvi

Configure the build environment. The configure script will pick automatically Java 8 even when you have more than one JDK installed.

💁‍♀️ The options --with-java=JAVA_HOME and --with-jvm-arch=(32|64) can be applied to the ./configure script in case you have a very specific build environment.

./configure

Compile and install the JAR and shared object library with

make && sudo make install

The JAR and the library will be installed to

/usr/local/share/java/jicmp6.jar
/usr/local/lib/libjicmp6.so
/usr/local/lib/libjicmp6.la

Configure OpenNMS Horizon with JICMP and JICMP6

To make the Horizon Core instance aware of the libraries, you can use the install command in the OpenNMS bin directory. It’s better to stop the Core service first.

sudo systemctl stop opennms
sudo -u opennms /opt/opennms/bin/install -dS

The following lines are important:

DEBUG: Platform is IPv6 ready: true
- searching for libjicmp.so:
  - trying to load /usr/local/lib/libjicmp.so: OK
- searching for libjicmp6.so:
  - trying to load /usr/local/lib/libjicmp6.so: OK

The path will be written to the /opt/opennms/etc/libraries.properties file which is used during startup.

When you start up the Core service, look at the manager.log. The algorithm detecting the Ping implementation tells you if OpenNMS Horizon is able to use it.

If you see permission errors look at the Troubleshooting ICMP permissions article which helps you to solve this problem.

If you don’t want to rely on the algorithm to determine the best ICMP implementation for Ping, you can enforce it by setting the org.opennms.netmgt.icmp.pingerClass property in /opt/opennms/etc/opennms.properties.d/icmp.properties.

# To use the JNI ICMPv4/ICMPv6 implementation, use the following property:
#org.opennms.netmgt.icmp.pingerClass=org.opennms.netmgt.icmp.jni6.Jni6Pinger
#
# To use the JNI ICMPv4 interface only, use the following property:
#org.opennms.netmgt.icmp.pingerClass=org.opennms.netmgt.icmp.jni.JniPinger
#
# To use the JNA ICMPv4/ICMPv6 implementation, use the following property:
#org.opennms.netmgt.icmp.pingerClass=org.opennms.netmgt.icmp.jna.JnaPinger

☢️ You can’t install just JICMP6 alone, you need JICMP as well. When I started OpenNMS with that configuration. The Ping implementation algorithm will fallback to JNA. If you enforce it with the property, the startup will crash with a thread dump like shown below with journalctl -u opennms.

Nov 28 13:16:55 rocky-dev systemd[1]: opennms.service: Supervising process 2701 which is not our child. We'll most likely not notice when it exits.
Nov 28 13:17:22 rocky-dev systemd[1]: opennms.service: Supervising process 2701 which is not our child. We'll most likely not notice when it exits.
Nov 28 13:22:03 rocky-dev systemd[1]: Stopping OpenNMS server...
Nov 28 13:22:05 rocky-dev opennms[2701]: 2024-11-28 13:22:05
Nov 28 13:22:05 rocky-dev opennms[2701]: Full thread dump OpenJDK 64-Bit Server VM (17.0.13+11-LTS mixed mode, sharing):
Nov 28 13:22:05 rocky-dev opennms[2701]: Threads class SMR info:
Nov 28 13:22:05 rocky-dev opennms[2701]: _java_thread_list=0x00007f832acaa2b0, length=488, elements={
Nov 28 13:22:05 rocky-dev opennms[2701]: 0x00007f83cc135f60, 0x00007f83cc137350, 0x00007f83cc140660, 0x00007f83cc141a20,
Nov 28 13:22:05 rocky-dev opennms[2701]: 0x00007f83cc142e20, 0x00007f83cc144240, 0x00007f83cc145c00, 0x00007f83cc147140,
Nov 28 13:22:05 rocky-dev opennms[2701]: 0x00007f83cc1505a0, 0x00007f83cc15bc30, 0x00007f83cc18b0e0, 0x00007f83cc02d950,
Nov 28 13:22:05 rocky-dev opennms[2701]: 0x00007f832909e910, 0x00007f832949e080, 0x00007f8329554290, 0x00007f8329555030,
Nov 28 13:22:05 rocky-dev opennms[2701]: 0x00007f8329556420, 0x00007f83295574d0, 0x00007f8329559780, 0x00007f832955c100,
Nov 28 13:22:05 rocky-dev opennms[2701]: 0x00007f832955d100, 0x00007f832955e100, 0x00007f83299cf3f0, 0x00007f8328f14670,
Nov 28 13:22:05 rocky-dev opennms[2701]: 0x00007f8328caec90, 0x00007f8328cb18e0, 0x00007f8328cb1e60, 0x00007f8328f130b0,

Creating RPM packages

When you run the ./configure scripts, you need verify the following output:

checking for rpmbuild... no
*** RPM Configuration Failed
*** Failed to find the rpmbuild program.  If you want to build rpm packages
*** indicate the path to the rpmbuild program using  --with-rpmbuild-prog=PROG

To solve this optional build dependency, you need to install the RPM build environment.

sudo dnf install -y rpm-build

Re-run ./configure and you should have now a RPM configuration which should look like this:

checking for rpmbuild... /usr/bin/rpmbuild
checking how rpm sets %{_rpmdir}... /home/rocky/rpmbuild/RPMS
checking how rpm sets %{_srcrpmdir}... /home/rocky/rpmbuild/SRPMS
checking where RPMs end up... /home/rocky/rpmbuild/RPMS/$(RPM_ARCH)/$(PACKAGE)-$(VERSION)-$(RELEASE).$(RPM_ARCH).rpm
checking where source RPMs end up... /home/rocky/rpmbuild/SRPMS/$(PACKAGE)-$(VERSION)-$(RELEASE).src.rpm
checking where source files go... /home/rocky/rpmbuild/SOURCES

The configure scripts, gives you now the additional make goal rpm which you can run with

make rpm

The RPM and SRPM build artifacts are located in your home directory in ${HOME}/rpmbuild

The procedure for JICMP and JICMP6 is exactly the same.

What can we do next?

There are now additional steps we can take from here, most notably:

Compile and install IPLIKE stored procedure in PostgreSQL
Compile and install RRDTool support using JRRD2
Building Core, Minion, and Sentinel RPM packages
Create Docker container images

Stay tuned and so long