Don’t Settle for Eventual Consistency

Stronger properties for low-latency geo-replicated storage

WYATT LLOYD, FACEBOOK; MICHAEL J. FREEDMAN, PRINCETON UNIVERSITY; MICHAEL KAMINSKY, INTEL LABS; DAVID G. ANDERSEN, CARNEGIE MELLON UNIVERSITY

Geo-replicated storage provides copies of the same data at multiple, geographically distinct locations. Facebook, for example, geo-replicates its data (profiles, friends lists, likes, etc.) to data centers on the east and west coasts of the United States, and in Europe. In each data center, a tier of separate Web servers accepts browser requests and then handles those requests by reading and writing data from the storage system

Don’t Settle for Eventual Consistency

 

Related:
Proving the Correctness of Nonblocking Data Structures
Eventual Consistency Today: Limitations, Extensions, and Beyond
Structured Deferral: Synchronization via Procrastination

Please Put OpenSSL Out of Its Misery

OpenSSL must die, for it will never get any better.

POUL-HENNING KAMP

The OpenSSL software package is around 300,000 lines of code, which means there are probably around 299 bugs still there, now that the Heartbleed bug — which allowed pretty much anybody to retrieve internal state to which they should normally not have access — has been fixed.

That’s really all you need to know, but you also know that won’t stop me, right?

Please Put OpenSSL Out of Its Misery

 

A Primer on Provenance

Better understanding of data requires tracking its history and context.

LUCIAN CARATA, SHERIF AKOUSH, NIKILESH BALAKRISHNAN, THOMAS BYTHEWAY, RIPDUMAN SOHAN, MARGO SELTZER, ANDY HOPPER

Assessing the quality or validity of a piece of data is not usually done in isolation. You typically examine the context in which the data appears and try to determine its original sources or review the process through which it was created. This is not so straightforward when dealing with digital data, however: the result of a computation might have been derived from numerous sources and by applying complex successive transformations, possibly over long periods of time.

A Primer on Provenance

 

Related:
Provenance in Sensor Data Management
CTO Roundtable: Storage
Better Scripts, Better Games

 

Multipath TCP

Decoupled from IP, TCP is at last able to support multihomed hosts.

CHRISTOPH PAASCH AND OLIVIER BONAVENTURE, UCL

The Internet relies heavily on two protocols. In the network layer, IP (Internet Protocol) provides an unreliable datagram service and ensures that any host can exchange packets with any other host. Since its creation in the 1970s, IP has seen the addition of several features, including multicast, IPsec (IP security), and QoS (quality of service). The latest revision, IPv6 (IP version 6), supports 16-byte addresses.

Multipath TCP

 

Related:
Passively Measuring TCP Round-trip Times 
You Don’t Know Jack about Network Performance 
TCP Offload to the Rescue

Major-league SEMAT: Why Should an Executive Care?

Becoming better, faster, cheaper, and happier

IVAR JACOBSON, PAN-WEI NG, IAN SPENCE, AND PAUL E. MCMAHON

In today’s ever more competitive world, boards of directors and executives demand that CIOs and their teams deliver “more with less.” Studies show, without any real surprise, that there is no one-size-fits-all method to suit all software initiatives, and that a practice-based approach with some light but effective degree of order and governance is the goal of most software-development departments.

Major-league SEMAT—Why Should an Executive Care?

 

Related:
The Essence of Software Engineering: The SEMAT Kernel
A Conversation with Steve Bourne, Eric Allman, and Bryan Cantrill
Voyage in the Agile Memeplex

The Logic of Logging

And the illogic of PDF

 

GEORGE NEVILLE-NEIL

 

Dear KV,

I work in a pretty open environment, and by open I mean that many people have the ability to become the root user on our servers so that they can fix things as they break. When the company started, there were only a few of us to do all the work, and people with different responsibilities had to jump in to help if a server died or a process got away from us. That was several years ago, but there are still many people who have rootly powers, some because of legacy and some because they are deemed too important to restrict. The problem is that one of these legacy users insists on doing almost everything as root and, in fact, uses the sudo command only to execute sudo su -. Every time I need to debug a system this person has worked on, I wind up on a two- to four-hour log-spelunking tour because he also does not take notes on what he has done, and when he’s finished he simply reports, “It’s fixed.” I think you will agree this is maddening behavior.

Routed by Root

 

http://queue.acm.org/detail.cfm?id=2588887

 

Eventually Consistent: Not What You Were Expecting?

Eventually Consistent: Not What You Were Expecting?

Wojciech Golab, Muntasir R. Rahman, Alvin AuYoung, Kimberly Keeton, Xiaozhou (Steve) Li

Methods of quantifying consistency (or lack thereof) in eventually consistent storage systems
Related:
Eventually Consistent
Eventual Consistency Today: Limitations, Extensions, and Beyond
BASE: An Acid Alternative

Scaling Existing Lock-based Applications with Lock Elision

Scaling Existing Lock-based Applications with Lock Elision

Andi Kleen

Lock elision enables existing lock-based programs to achieve the performance benefits of nonblocking synchronization and fine-grain locking with minor software engineering effort.
Related:
Proving the Correctness of Nonblocking Data Structures
Erlang for Concurrent Programming
Trials and Tribulations of Debugging Concurrency