Apache Ignite

Monday September 20, 2021

Apache Ignite 2.11: Stabilization First

The new Apache Ignite 2.11 was released on September 17, 2021. It can be considered to be a greater extent as a stabilization release that closed a number of technical debts of the internal architecture and bugs. Out of more than 200 completed tasks, 120 are bug fixes. However, some valuable improvements still exist, so let's take a quick look at them together.

Thin Clients

Partition awareness is enabled by default in the 2.11 release and allows thin clients to send query requests directly to the node that owns the queried data. Without partition awareness, an application executes all queries and operations via a single server node that acts as a proxy for the incoming requests.

The support of Continuous Queries added to the java thin client. For the other supported features, you can check - the List of Thin Client Features.

Cellular-clusters Deployment

The Apache Ignite internals has the so-called switch (a part of Partition Map Exchange) process that is used to perform atomic execution of cluster-wide operations and move a cluster from one consistent state to another, for example, a cache creation/destroy, a node JOIN/LEFT/FAIL operations, snapshot creation, etc. During the switching process, all user transactions are parked for a small period of time which in turn increases the average latency and decreases throughput of the overall cluster.

Splitting the cluster into virtual cells containing 4-8 nodes may increase the total cluster performance and minimize the influence of one cell on another in case of node fail events. Such a technique also significantly increases the recovery speed of transactions on cells not affected by failing nodes. The time when transactions are parked also decreases on non-affected cells which in turn decreases the worst latency for the cluster operations overall.

From now on, you can use the RendezvousAffinityFunction affinity function with ClusterNodeAttributeColocatedBackupFilter to group nodes into virtual cells. Since the node baseline attributes are used as cell markers the corresponding BASELINE_NODE_ATTRIBUTES system view was added.

See benchmarks below that represent the worst (max) latency, which happens in case of node left/failure/timeout events on broken and alive cells.

723rhosidfgu4787fh9sdhf.png

New Page Replacement Policies

When Native Persistence is on and the amount of data, which Ignite stores on the disk, is bigger than the off-heap memory amount allocated for the data region, another page should be evicted from the off-heap to the disk to preload a page from the disk to the completely full off-heap memory. This process is called page replacement. Previously, Apache Ignite used the Random-LRU page replacement algorithm which has a low maintenance cost, but it has many disadvantages and greatly affects the performance when the page replacement is started. On some deployments, administrators even force a cluster restart periodically to avoid page replacement. There are a few new algorithms available from now on:

  • Segmented-LRU Algorithm
  • CLOCK Algorithm

Page replacement algorithm can be configured by the PageReplacementMode property of DataRegionConfiguration. By default, the CLOCK algorithm is now used. You can check the Replacement Policies in the documentation for more details.

Snapshot Restore And Check Commands

Check

All snapshots are fully consistent in terms of concurrent cluster-wide operations as well as ongoing changes with Ignite. However, in some cases and for your own peace of mind, it may be necessary to check the snapshot for completeness and for data consistency. The Apache Ignite is now delivered with a built-in snapshot consistency check commands that enable you to verify internal data consistency, calculate data partitions hashes and pages checksums, and print out the result if a problem is found. The check command also compares hashes calculated by containing keys of primary partitions with corresponding backup partitions and reports any differences.

# This procedure does not require the cluster to be in the idle state.
control.(sh|bat) --snapshot check snapshot_name

Restore

Previously, only the manual snapshot restore procedure was available by fully copying persistence data files from the snapshot directory to the Apache Ignite work directory. The automatic restore procedure allows you to restore cache groups from a snapshot on an active cluster by using the Java API or command line script (using CLI is recommended). Currently, the restore procedure has several limitations, so please check the documentation pages for details.

Start restoring all user-created cache groups from the snapshot "snapshot_09062021".
control.(sh|bat) --snapshot restore snapshot_09062021 --start

# Start restoring only "cache-group1" and "cache-group2" from the snapshot "snapshot_09062021".
control.(sh|bat) --snapshot restore snapshot_09062021 --start cache-group1,cache-group2

# Get the status of the restore operation for "snapshot_09062021".
control.(sh|bat) --snapshot restore snapshot_09062021 --status

# Cancel the restore operation for "snapshot_09062021".
control.(sh|bat) --snapshot restore snapshot_09062021 --cancel

Tuesday September 14, 2021

Apache Ignite Momentum: Highlights from 2020-2021

When Apache Ignite entered the Apache Software Foundation (ASF) Incubator in 2014, it took less than a year for the project and its community to graduate from the Incubator and become a top-level project for the ASF. Since then, Ignite has experienced a significant and steady growth in popularity, and it has been used by thousands of application developers and architects to create high-performance and scalable applications used by millions of people daily. In this article, we’ll recap the achievements of Ignite in 2020-2021.


Ignite is Ranked as a Top 5 Project

The ASF has ranked Apache ignite as a Top 5 project in various categories since 2017. That year, Ignite was in the Top 5 of Apache Project Repositories by Commits and most active Apache mailing lists. Today, the momentum continues, and Ignite continues to be ranked as a Top 5 project in multiple categories: second on the Top 5 big data user lists, third on the Top 5 big data dev lists, second on the Top 5 of all user lists, third on the Top 5 repos by size.

Of greatest significance, the continued Top 5 ranking on the “dev list” reflects an active community of contributors who are committed to keeping the code base growing, while the Top 5 ranking on the “user list” means that more and more Ignite application developers come to the community to ask questions – indicating continued growth in adoption.

The Worldwide Ignite community is Engaged

This broad and growing interest in Apache Ignite has continued over the last year and a half. However, faced with the pandemic and shelter-in-place orders around the world, the community sought ways to stay in touch and continue sharing experiences. The community naturally turned to a virtual format and established two new successful programs.

The first was a series of Ignite Virtual Meetups, where Apache Ignite users, developers, committers, contributors and architects worldwide could share experiences on a wide range of topics, ask questions, and help drive the project forward. Since these virtual meetups began, the community has already held 17 events, which were attended by hundreds of community members and developers.

The second new program was launched this May with the virtual Ignite Summit, the first global conference designed for the entire Ignite community. Twenty-five speakers from industry-leading companies including finance, biotech, health & fitness, construction and cloud computing led 15 hours of discussion about how Apache Ignite delivers the performance and scale required to address the world’s most challenging computational and hybrid transactional/analytical processing requirements. The Summit had attendees from North America, Latin America, EMEA and APAC. Remarkably, attendees spent an average of nearly 5 hours at the event!

Innovation Continues at a Rapid Pace

Over the last year and a half, the community has released five new versions of Ignite 2.x. The releases introduce numerous improvements and optimizations, including major features, such as new monitoring and profiling frameworks, cluster snapshots, encoding keys rotation for transparent data encryption, and more.

The community also put significant effort into contributing and releasing new documentation, which is now hosted on the Ignite website. Since the new documentation was posted, it has become the most visited resource on the website – a clear indication that it is helping Ignite developers make faster, easier progress on their Ignite development and optimization tasks.

Further, Igniters have begun working on the next major release, Ignite 3.0, which introduces significant usability improvements, a new SQL engine based on Apache Calcite, a Raft-based consistency protocol, and many other improvements. Users can already try the first two Alpha versions:

The payoff – Ignite Downloads Continue to Soar

The inherent benefits of Apache Ignite, combined with all the effort of a dedicated community, has resulted in a popular project that continues to see increasing adoption. Ignite Maven monthly downloads are skyrocketing, and we have seen a 65% year-over-year growth in downloads so far in 2021, resulting in hundreds of thousands of downloads each month.

We eagerly look forward to the full release of Apache ignite 3.0 and fully expect downloads, adoption and community enthusiasm to continue to soar. Good luck to the Ignite community!

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