Reading List: Interviews

The Horrifically Dystopian World of Software Engineering Interviews

I had a similar experience after getting fired from twitter. I attend 20-30 interviews and I managed to clear one. The experience frustrated me to no end.

My personal experience at Square interview was one of humiliation. I was escorted out after the 1st round as I could not write code.

cottage industry

There is a cottage industry springing up around passing interviews - All of this algorithm challenge hubub started with popular companies like Google. There were several engineers who worked at these popular tech companies that saw an opportunity to make a few bucks be offering prep material. There were two influential books written on the subject: Cracking the Coding Interview and Elements of Programming Interviews. Both of these books offer guided interview preparation material. The problem is that the industry got a hold of these books and tailored their interviews to the book’s material.

This is real. So many start-ups help you prepare for the interview.

Acceptance

Complaining about it wont do any good. - Sooner or later I’m going to have to get another job. Even if I don’t like the methodology, I am going to have to go through the loop again.

The final conclusions makes it a balanced article, in my opinion.

There is no good way to find the right candidates. These interviews of-course help test if the candidate can code, has prepared for the interview and is taking the process seriously. I am with this process until we find a better one.


ZooKeeper- Wait-free coordination for Internet-scale systems

By Patrick Hunt and Mahadev Konar of Yahoo! Grid and Flavio P. Junqueira and Benjamin Reed of Yahoo! Research

wait-free

Our system, Zookeeper,hence implements an API that manipulates simple wait-free data objects organized hierarchically as in file systems.

Linearizable writes

With ZooKeeper, we are able to implement all coordination primitives that our applications require, even though only writes are linearizable.

Ordering Gaurantees

ZooKeeper has two basic ordering guarantees.

Linearizable writes: All requests that update the state of ZooKeeper are serializable and respect precedence.

FIFO client order: All requests from a given client are executed in the order that they were sent by the client.

The important design of the Zookeeper was in the Client API used by the clients, server is a well defined architecture.

I used Zookeeper for the Packer service, which is a service to manage artifacts on Aurora scheduler (on Mesos) at twitter. ZK was used along with hadoop for storing package metadata. This was overkill for simple operation, and it was decided migrate the service from ZK to a relational database like MySQL.

I had worked on the client of this service in python and also wrote certain parts the migration client in java.


Byzantine Fault Tolerance

Zookeeper is not Byzantine Fault Tolerant. Author say for the production uses they have have not observed the failure that could have been prevented by then proposed systems to make Zookeeper Byzantine Fault Tolerant.


Chubby

The Chubby lock service for loosely-coupled distributed systems By Mike Burrows, Google Inc

intended use

It is intended for use within a loosely-coupled distributed system consisting of moderately large numbers of small machines connected by a high-speed network. For example, a Chubby instance (also known as a Chubby cell) might serve ten thousand 4-processor machines connected by 1Gbit/s Ethernet. Most Chubby cells are confined to a single data centre or machine room, though we do run at least one Chubby cell whose replicas are separated by thousands of kilometres.

backup

Every few hours, the master of each Chubby cell writes a snapshot of its database to a GFS file server in a different building. The use of a separate building ensures both that the backup will survive building damage, and that the backups introduce no cyclic dependencies in the system; a GFS cell in the same building potentially might rely on the Chubby cell for electing its master.

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