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Top 23 Java High Performance Projects
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> are they using a connection pooler
We use Hikari [1] an in-process connection pooler. We didn't opt for pgbouncer at al, because we didn't want to add the extra infra yet.
> since what they did in code can be natively done with PgBouncer, PgCat, et al.
Can you point me to a reference I could look at, about doing a major version upgrade with PgBouncer et al? My understanding that we would still need to write a script to switch masters, similar to what we wrote.
> all the active connections
The active connections we were referring too were websocket connections, we haven't had problems with PG connections.
Right now the algorithm we use to find affected queries and notify websockets starts to falter when the number of active websocket connections get too high. We're working on improving it in the coming weeks. I'll update the essay to clarify.
> I did feel for them here:
Thank you! That part was definitely the most frustrating.
[1] https://github.com/brettwooldridge/HikariCP
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InfluxDB
InfluxDB – Built for High-Performance Time Series Workloads. InfluxDB 3 OSS is now GA. Transform, enrich, and act on time series data directly in the database. Automate critical tasks and eliminate the need to move data externally. Download now.
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LMAX have an open source version of the disruptor in GitHub https://github.com/LMAX-Exchange/disruptor
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Project mention: Ash Framework – Model your domain, derive the rest | news.ycombinator.com | 2025-05-14
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seatunnel
SeaTunnel is a next-generation super high-performance, distributed, massive data integration tool.
Project mention: How to Build Real-Time Data Pipelines with SQL Server CDC and Apache SeaTunnel | dev.to | 2025-06-17Change Data Capture (CDC) is a powerful feature in SQL Server that enables real-time data integration by tracking INSERT, UPDATE, and DELETE operations on tables. In this article, we’ll explore how SQL Server CDC works, and how to integrate it seamlessly with Apache SeaTunnel to build efficient, scalable data pipelines for AI-ready systems.
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Project mention: Fahmatrix – A Lightweight, Pandas-Like DataFrame Library for Java (GitHub) | news.ycombinator.com | 2025-05-16
Always great to see efforts to make working with data frames easier. Here are some similar data frame libraries for Java:
https://github.com/jtablesaw/tablesaw
https://github.com/dflib/dflib
My preferred way is just use duckdb java API. I didn't see anything better in performance/efficiency. Also a SQL query is often easier to write
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SaaSHub
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Eclipse Collections
Eclipse Collections is a collections framework for Java with optimized data structures and a rich, functional and fluent API.
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tlaplus
TLC is a model checker for specifications written in TLA+. The TLA+Toolbox is an IDE for TLA+.
TLA+ toolbox binaries — a Java based TLA+ IDE;
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fastutil
fastutil extends the Java™ Collections Framework by providing type-specific maps, sets, lists and queues.
Project mention: Do you know how to evaluate performance of your Java applications? | dev.to | 2025-02-27For a request with thousands of IDs (e.g., batch validation), each Integer requires unboxing. The alternative? Use int[] and IntHashSet (from the FastUtil library).
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GS Collections
GS Collections has been migrated to the Eclipse Foundation, re-branded as Eclipse Collections. https://www.eclipse.org/collections/
3. Eclipse Collections
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bitsail
BitSail is a distributed high-performance data integration engine which supports batch, streaming and incremental scenarios. BitSail is widely used to synchronize hundreds of trillions of data every day.
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linstor-server
High Performance Software-Defined Block Storage for container, cloud and virtualisation. Fully integrated with Docker, Kubernetes, Openstack, Proxmox etc.
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9. Koloboke
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ActiveJ
ActiveJ is an alternative Java platform built from the ground up. ActiveJ redefines core, web and high-load programming in Java, providing simplicity, maximum performance and scalability
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Java High Performance discussion
Java High Performance related posts
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How to Build Real-Time Data Pipelines with SQL Server CDC and Apache SeaTunnel
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How to Seamlessly Integrate SeaTunnel MySQL-CDC with Databend: Formats Explained & Best Practices
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A New Paradigm of Natural Language Data Integration: In-depth Exploration of SeaTunnel MCP
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Apache SeaTunnel has surpassed 8,500 GitHub Stars
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Contributor Spotlight: How I Brought Apache SeaTunnel from First PR to Production
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Practical experience in deploying K8s clusters in Apache SeaTunnel separated cluster mode
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You’re Invited: Apache SeaTunnel Biweekly Community Meeting on April 8, 2025
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A note from our sponsor - SaaSHub
www.saashub.com | 21 Jun 2025
Index
What are some of the best open-source High Performance projects in Java? This list will help you:
# | Project | Stars |
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1 | HikariCP | 20,505 |
2 | Disruptor | 17,851 |
3 | Vert.x | 14,504 |
4 | seatunnel | 8,592 |
5 | fastjson2 | 4,063 |
6 | JCTools | 3,675 |
7 | Tablesaw | 3,646 |
8 | Agrona | 3,018 |
9 | Eclipse Collections | 2,518 |
10 | tlaplus | 2,451 |
11 | fastutil | 1,890 |
12 | GS Collections | 1,817 |
13 | bitsail | 1,652 |
14 | Rapidoid | 1,629 |
15 | Simple Java Mail | 1,254 |
16 | linstor-server | 1,084 |
17 | DSL-JSON | 1,032 |
18 | Koloboke | 1,014 |
19 | HPPC | 1,014 |
20 | ActiveJ | 961 |
21 | cicada | 949 |
22 | Zero-Allocation-Hashing | 808 |
23 | colfer | 749 |