ADF Performance Monitor: Thread Wait and Blocked Time

Uncategorized
| May 6, 2020

Last week we had a new version of the ADF Performance Monitor available – version 9.5.

In this blog I will write on one of the new features; thread wait and thread blocked time of requests. Sometimes we cannot explain a poor performance, disruptions, hiccups. If we dive into the world of Java threads, we often can. It can be that some threads were waiting on some resources or were being blocked. Or if (more...)

Reconnect Plugin

Uncategorized
| May 2, 2020

On the forum of PL/SQL Developer there was a message by my good friend Erik van Roon. He was having trouble with Reconnecting. Even my plugin didn’t help him. I figured I should update the plugin.

The plugin wasn’t really updated since its first version. Only some cosmetic changes, like adding new buttons.
I have decided to make use of all the features of the newer versions of PL/SQL Developer. The new version now has (more...)

Add tests for Angular and Node.js webapp in Azure Pipelines (part 3)

Uncategorized
| May 1, 2020

In the previous article I showed how to build a webapp in the Azure pipeline. In this article I will explain to you how you run tests in your pipeline. I will show you how to do this for both Angular and Node.js.

Adding tests frontend – Angular

Adding tests to the frontend is a bit harder than for the backend, so will we start out with this.
This article helped me out a (more...)

Azure Pipeline: Build Angular and Node.js webapp (part 2)

Uncategorized
| Apr 30, 2020

In the previous article, we discussed how we can set up a pipeline with multiple stages in Azure Pipelines. In this article we will discuss how we can build the Angular and Node.js apps in the pipeline itself.
I usually put all the build processes in one stage. In that stage I have one job for the backend and one job for the frontend. Check out the Azure documentation on basics about the (more...)

What happened to NEXTGRES?

Uncategorized
| Apr 22, 2020
I’ve received a few questions in regard to the state of my company, NEXTGRES, and why the site now only contains a terse reference to the Janus Database Compatibility System. While it’s not specifically related to Oracle Database internals, as it’s been discussed on my blog and Twitter for many years, here’s an update. MisconceptionsOver […]

Distributed Deep Learning for Physics with TensorFlow and Kubernetes

Uncategorized
| Mar 26, 2020
Summary: This post details a solution for distributed deep learning training for a High Energy Physics use case, deployed using cloud resources and Kubernetes. You will find the results for training using CPU and GPU nodes. This post also describes an experimental tool that we developed, TF-Spawner, and how we used it to run distributed TensorFlow on a Kubernetes cluster.

Authors: Riccardo.Castellotti@cern.ch and Luca.Canali@cern.ch

A Particle Classifier

  
This work (more...)

Development Standards for API Policies?

Uncategorized
| Dec 16, 2019

When it comes to development, we have had coding standards for almost as long as we have been coding. We tend to look at coding standards for purposes of helping to promote good quality code and reduce the likelihood of bugs and so on. But they also help with readability, making it easy to navigate a code base and so on. This is sufficiently important that there is a vast choice of tools to help (more...)

PostgreSQL Invalid Page and Checksum Verification Failed

Uncategorized
| Nov 8, 2019

At the Seattle PostgreSQL User Group meetup this past Tuesday, we got onto the topic of invalid pages in PostgreSQL. It was a fun discussion and it made me realize that it’d be worth writing down a bunch of the stuff we talked about – it might be interesting to a few more people too!

Invalid Page In Block

You see an error message that looks like this:

ERROR: invalid page in block 1226710  (more...)

Radical Candor

Uncategorized
| Oct 23, 2019

Radical Candor

Radical Candor — The Surprising Secret to Being a Good Boss

Buy the book: Radical Candor by Kim Scott

deltalounge

Speeding up APEX Static Application and Workspace Files

Uncategorized
| Jul 24, 2019

A few years ago it was deemed state-of-the-art to store any kind of extra resources (images, css/js-files) directly on the webserver.

Of course this was just the best-practice, left with many who were not able to follow because of company restrictions: no access to web server, not allowed to store files, too many regulations, and so on.

Luckily APEX 5++ gave us nicely working Static Application Files and Static Workspace Files. Now everyone is using (more...)

First episode of the bol.com TechLab podcast

Uncategorized
| May 2, 2019

First episode of the bol.com TechLab podcast

Today we released the first episode of the bol.com TechLab podcast. The subject of this first episode is our Kotlin adoption journey.

In this podcast, we share our experience with you to learn and entertain. Peeking behind the screens of IT and Tech in general at bol.com. Showing you our approach to IT, e-commerce and retail platforms. We have a lot of fun creating the (more...)

Scripts to deal with SQL Plan Baselines, SQL Profiles and SQL Patches

Uncategorized
| Dec 15, 2018

To mitigate SQL performance issues, I do make use of SQL Plan Baselines, SQL Profiles and SQL Patches, on a daily basis. Our environments are single-instance 12.1.0.2 CDBs, with over 2,000 PDBs. Our goal is Execution Plan Stability and consistent performance, over CBO plan flexibility. The CBO does a good job, considering the complexity imposed by current applications design. Nevertheless, some SQL require some help in order to enhance their plan stability.

(more...)

SparkMeasure, a tool for performance troubleshooting of Apache Spark workloads

Uncategorized
| Aug 23, 2018

SparkMeasure 

 SparkMeasure simplifies the collection and analysis of Spark task metrics data. It is also intended as a working example of how to use Spark listeners for collecting and processing Spark performance metrics.
The work on sparkMeasure has been previously presented in this blog with examples. Recently, an updated version of sparkMeasure (version 0.13) introduces additional integration for the PySpark and Jupyter environments, improved documentation and additional features provided by the community via (more...)

Day 2 problems in the Cloud

Uncategorized
| Jan 26, 2018

Day 2 problems in the Cloud

When moving to the Cloud companies run into “Day 2 problems”. The technology, interfaces and how to use all the stuff are super easy however on the second day comes the real challenge: How to use all this great stuff in a structured way on company/enterprise level?

Here is a great read on “Day 2 problems in the Cloud“. Day 2 is a management problem, not a (more...)

How does IT work at bol.com?

Uncategorized
| Dec 13, 2017

How does IT work at bol.com?

Check part 1 of the video we created on How IT works at bol.com.

deltalounge

Performance Analysis of a CPU-Intensive Workload in Apache Spark

Uncategorized
| Sep 29, 2017
Topic: This post is about techniques and tools for measuring and understanding CPU-bound and memory-bound workloads in Apache Spark. You will find examples applied to studying a simple workload consisting of reading Apache Parquet files into a Spark DataFrame.
 

Why are the topics discussed here relevant

Many workloads for data processing on modern distributed computing architectures are often CPU-bound. Typical servers underlying current data platforms have a large and increasing amount of RAM and (more...)

Two interesting reads on team structure and focus

Uncategorized
| Sep 29, 2017

Two interesting reads on team structure and focus

(Re)discovered two interesting reads on team structure and focus this week that I like to share.

Pioneers, Settlers and Town Planners

pioneer, settler and town planner The Pioneers, Settlers and Town Planners approach help structure organisations and teams. It takes into account how activities and practices move from chaotic (poorly understood, uncertain, constantly changing, rare, future source of worth) to more linear (well-defined, predictable, stable, common, cost of doing business) and how (more...)

Video applying web scale patterns – Codemotion 2017

Uncategorized
| Aug 3, 2017

Video applying web scale patterns – Codemotion 2017

During my holiday the video of my applying web scale patterns at Codemotion Amsterdam 2017 was released on youtube.

deltalounge

Travis Law

Uncategorized
| Aug 3, 2017

Travis Law

Travis’s Law:

Our product is so superior to the status quo that if we give people the opportunity to try it, they will defend it and demand its right to exist.

Travis Law is a quote from a speech by Travis Kalanick founder of Red Swoosh and wider known Uber. In his CEO role at Uber, there have been quite some scrimmages with local governments and unions. This law is one of the (more...)

Presentation Applying “web scale” patterns in the bol.com back office

Uncategorized
| May 18, 2017

Presentation Applying “web scale” patterns in the bol.com back office

Codemotion web scale pattern presentationThis week at Codemotion I gave a presentation on web scale patterns and how we apply them in the bol.com back office services. Codemotion is the biggest tech conference in Italy and one of the most important in Europe.

The presentation shows how we go from business goals to software patterns. The following patterns were covered: CQRS, event sourcing, polyglot persistence (more...)