Apr 4 2018
At Allegro, feature velocity is a top priority. We believe that one of our critical competitive advantages
is the rate at which we introduce new features. In order to achieve a high feature velocity, one of the architectural
choices that Allegro made a while back was to move to microservice architecture. So when somebody uses Allegro, a
request comes in (and we just have a hypothetical example here) to service D — and we can imagine a service D being a
proxy or an API layer — and whatever that service is, it is not going to have all the information it needs to serve a
response. So the service D is going to reach out to service C and service F, and F in turn will reach out to A, and it
will in turn reach out to B and E, and you see that this very quickly gets complicated. Allegro has somewhere around
500 microservices, so you can imagine how complicated the communication map looks.
Mar 12 2018
This is a post for those seeking to accomplish business goals and ensure stability of the solutions developed
while maintaining focus on people. The model of three basic psychological needs that I’m presenting here may be
useful for leaders, agile coaches, and scrum masters. I also encourage developers to do some self-reflection.
This is the knowledge I’ve gained at the World Conference of Transactional Analysis in Berlin.
Transactional Analysis (TA) is a theory of interpersonal relationships developed by Eric Berne which has a
practical application in various fields, including organizations.
Feb 15 2018
Application release process, or in fact software development process, as a release is the final stage of application
development, is not an easy thing. Books and IT websites discuss many approaches and each has its supporters and
opponents. On the one hand, you have product owners, project managers and customers who want a ready-to-use application
as soon as possible. On the other hand, we developers and testers, would like to release an application of the highest
quality, which may affect the delivery time. Balancing these needs is a hard nut to crack. Usually, both
sides need to make some compromises to establish a common way of working. For developers and testers, it involves
answering several questions concerning software development methods, skills, use of manual or automated testing, and
storage of test cases and test logs. In this article I describe best practices and tips for starting a new project.
I think that by following them, you will make the software development process as effective as possible and adjusted
to conditions of your project.
Jan 11 2018
Apache Mesos is an open-source project to manage computer clusters. In this
article we present one of its components called Executor and more specifically
the Custom Executor. We also tell you why you should consider writing your own
executor by giving examples of features that you can benefit from by taking
more control over how tasks are executed. Our executor implementation is
available at github.com/allegro/mesos-executor
Nov 24 2017
Some of our engineers run their own tech blogs.
We encourage them to move here, but for various reasons,
they prefer to publish on private blogs. We respect their decisions.
What we can do is to gather all the blog posts published by allegro.tech
engineers around the web in the one place.
Jul 24 2017
In this post I present a story of a bug that hit us recently. Everything was
caused by unexpected (although documented) behavior of Go built-in function
append. This bug has lived silently
for nearly a year in
allegro/marathon-consul. Ensure
you run the latest version.
Jun 29 2017
I bet you have found this article after googling some of the issues you encounter when working with a Hadoop cluster.
You probably deal with Hive queries used for exploratory data analysis that are processed way too long. Moreover, you
cannot adapt Spark in your organization for every use case because of the fact that writing jobs requires quite strong
programming skills. Clogged Yarn queues might be your nightmare and waiting for the launch of the container when you run
even a small query drives you mad. Before we deployed Presto — a Fast SQL engine provided by Facebook — our
analysts struggled with these problems on a regular basis.
Jun 12 2017
Last year Agile Testing Days Conference was held between 6th and 8th December in Potsdam, Germany.
According to statistics provided by organizers there were around 600 attendants and about 30 speakers in keynotes / workshops.
During the whole event around 22 different workshops took place, 9 keynotes
and around 30 other speeches / presentations divided into 7 parallel tracks.
I had the opportunity to attend the first two days of the conference and in
this article I’d like to share with you a short review of the most
interesting sessions and my impressions about the event.
Apr 21 2017
In our services ecosystem it’s usually the case that services can handle
a limited amount of requests per second.
We show how we introduced a new algorithm for our publish-subscribe queue system.
The road to production deployment highlights some key distributed systems’ takeaways we’d like to discuss.
Mar 20 2017
Running
Mesosphere
Marathon
is like running… a marathon. When you are
preparing for a long distance run, you’ll often hear about
Hitting the wall.
This effect is described mostly in running and cycling but affects all
endurance sports. It happens when your body does not have enough glycogen to
produce power and this results in a sudden “power loss” so you can’t run
anymore. At Allegro
we have experienced a similar thing with Mesosphere Marathon. This
is our story on using Marathon in a growing microservice ecosystem, from tens of
tasks and a couple applications, to thousands of tasks and over a hundred applications.
If there is no mention of Marathon version, it is 1.3.10 and below; we need
some time to test and deploy the latest 1.4 release.
If you are interested in how our ecosystem is built, take a look at below MesosCon
presentation.
Jan 26 2017
Caching is a good and well-known technique used to increase application performance and decrease overall system load.
Usually small or medium data sets, which are often read and rarely changed, are considered as a good candidate for
caching. In this article we focus on determining optimal cache size based on big data techniques.
Dec 29 2016
Understanding data model is sufficient to design good database schema in RDBMS (relational
database management system). Having this knowledge you are able to construct normalized tables, add appropriate
constraints and finally create indexes to speed up queries.
In the world of NoSQL there are no simple solutions, rules and answers. That’s why we can only talk about
patterns, tips and hints. MongoDB is not an exception. Besides the comprehension of stored data, deep
understanding of an access pattern, how data is searched, inserted and updated by an application is needed.
Dec 19 2016
At Allegro we are faced with a technical challenge: how to recognize whether a given image
(a product thumbnail) shows just a product itself. One of the things that we would like to detect is when the product
is surrounded by a frame. In this post we would like to present our approach for detecting a frame in the image.
Nov 28 2016
Are you developing a service and planning to make it publicly available? Do you want developers of mobile applications to get integrated
with your API fast and painless? Do you care how stable and predictable mobile applications using your service are?
Oct 24 2016
We’re all familiar with
TDD, or at least write unit tests for our software,
but unit tests won’t check application state after complex UI interactions.
If you want to make sure that an application behaves correctly when users interact with it,
then you need to write UI tests.
Oct 17 2016
In July we attended the scientific conference SIGIR 2016 held in Pisa, Italy. SIGIR is an annual conference
related to new advances in Information Retrieval. The shortcut is for
Special Interest Group on Information Retrieval.
This is an annual conference with the highest ranking at
Microsoft Academic Research in Information Retrieval field
field and the 16th in the ranking in the whole Computer Science field.
Sep 30 2016
In everyday work programmers are facing various problems. We would like to focus on two of them: big systems
with non-blocking API and specific business needs that can be solved using Expression Language. Hold tight!
Sep 23 2016
High performance and availability are always hard to achieve,
and microservice architecture is no exception.
In the microservices world, every user request sent to a frontend application triggers a cascade
of remote calls.
The frontend application calls API facades, API facades ask backend services,
backend services communicate with databases and even more backend services.
Statistics work against you. Latencies add up but failure probabilities combine
by multiplication.
The more services are engaged in a flow, the more threats for performance and availability.
Sep 21 2016
This article is a part of CQK Top 10 series.
Sep 21 2016
This article is a part of CQK Top 10 series.
Sep 21 2016
This article is a part of CQK Top 10 series.
Sep 16 2016
Code reviews play an important role in how we develop software at Allegro. All code we developers write is reviewed
by our peers. If you apply for a job with us, we may ask you to review a sample piece of code during your interview. A code review done
right carries a lot of value, but if done wrong it can become a waste of time. In this article I will describe what I think makes a good
code review, how reviews have evolved over time at the teams I worked with and what you can do in order to make code reviews worthwhile.
Sep 2 2016
At Allegro we want to be sure that our software works as designed. That’s why tests are so important to us.
In several projects we are using Elasticsearch. In order to
make writing integration tests that uses Elasticsearch easier, we’ve created a little tool called
embedded-elasticsearch. It sets up Elasticsearch
instance that you need for your tests (including installation of plugins) and gives you full control of it.
Aug 9 2016
This article tells a story of chasing an iOS bug – a bug hidden so deep that it
required many different skills and debugging on different levels to identify it.
I think every native mobile app developer (not only an iOS developer) will find
this text interesting. Non-mobile developers may find it an intriguing read as
well.
Jun 20 2016
Kotlin may seem like a new kid on the block — itʼs been officially released only in February.
Its history however dates a few years back
and itʼs mature and stable enough to be used for developing solid reliable applications.
Therefore at Allegro we decided to give it a chance — we built our new
shiny server-side system using Kotlin as its primary language and we do not regret it.
