Apache Ignite Tip: Peer Class Loading Deployment Magic

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Apache Ignite Tip: Peer Class Loading Deployment Magic

Apache Ignite is great for modern data processing. It has a feature called Zero Deployment which is very useful for P2P class loading.

· Big Data Zone ·
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In this article, I will focus on Zero Deployment in Apache® Ignite™.

There is a very useful feature in Apache Ignite for inter-node byte-code exchange called peer class loading, also referred to as P2P class loading. Let’s take a look at this in little more detail.

Peer Class Loading

In Apache Ignite, there is a special distributed ClassLoader which, if enabled, will automatically redeploy Java or Scala code on every node in a grid each time the code changes.

Let’s review a simple Java code snippet from the Apache Ignite documentation shown in Figure 1.

IgniteCluster cluster = ignite.cluster();

// Compute instance over remote nodes.

IgniteCompute compute = ignite.compute(cluster.forRemotes());

// Print hello message on all remote nodes.

compute.broadcast(() -> System.out.println("Hello node: " + cluster.localNode().id()));

Figure 1: "Hello node" example

This code enables a “Hello node” message to be broadcast to all nodes in an Apache Ignite cluster. The code would run on all remote nodes without the need for a deployment step. So, if the code were changed, it would not be necessary to manually redeploy the code; the special distributed ClassLoader would manage the redeployment for us.

To configure peer class loading, we can use either an XML config file or program code. Figure 2 shows an example from the Apache Ignite documentation that uses Java code.

IgniteConfiguration cfg = new IgniteConfiguration();

// Enable or disable peer class loading.


// Start Ignite node.

Ignite ignite = Ignition.start(cfg);

Figure 2: Enable peer class loading

Specifically, there is a simple two-step process involved for using peer class loading, as follows:

  1. If a class that is called is already available locally on a node, then Apache Ignite will use this class and there is no requirement to request the class from a peer node.
  2. If a class is not available locally, a request is sent to the originating node. This originating node will send the byte-code so that the class can be loaded on the worker node.

Obviously, there are significant productivity gains in using peer class loading.


With peer class loading there are:

  • No Ant scripts to run.
  • No Jar files to copy or FTP.
  • No nodes to restart.

For developers working with Apache Ignite, peer class loading provides significant productivity gains, thus saving time and effort.

apache ignite ,big data ,peer class loading ,tutorial ,zero deployment

Published at DZone with permission of Akmal Chaudhri . See the original article here.

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