jm + qcon   7

Building a Modern Website for Scale (QCon NY 2013) [slides]
some great scalability ideas from LinkedIn. Particularly interesting are the best practices suggested for scaling web services:

1. store client-call timeouts and SLAs in Zookeeper for each REST endpoint;
2. isolate backend calls using async/threadpools;
3. cancel work on failures;
4. avoid sending requests to GC'ing hosts;
5. rate limits on the server.

#4 is particularly cool. They do this using a "GC scout" request before every "real" request; a cheap TCP request to a dedicated "scout" Netty port, which replies near-instantly. If it comes back with a 1-packet response within 1 millisecond, send the real request, else fail over immediately to the next host in the failover set.

There's still a potential race condition where the "GC scout" can be achieved quickly, then a GC starts just before the "real" request is issued. But the incidence of GC-blocking-request is probably massively reduced.

It also helps against packet loss on the rack or server host, since packet loss will cause the drop of one of the TCP packets, and the TCP retransmit timeout will certainly be higher than 1ms, causing the deadline to be missed. (UDP would probably work just as well, for this reason.) However, in the case of packet loss in the client's network vicinity, it will be vital to still attempt to send the request to the final host in the failover set regardless of a GC-scout failure, otherwise all requests may be skipped.

The GC-scout system also helps balance request load off heavily-loaded hosts, or hosts with poor performance for other reasons; they'll fail to achieve their 1 msec deadline and the request will be shunted off elsewhere.

For service APIs with real low-latency requirements, this is a great idea.
gc-scout  gc  java  scaling  scalability  linkedin  qcon  async  threadpools  rest  slas  timeouts  networking  distcomp  netty  tcp  udp  failover  fault-tolerance  packet-loss 
june 2013 by jm
Videos from the Continuous Delivery track at QCon SF 2012
Think we'll be watching some of these in work soon -- Jez Humble's talk (the last one) in particular looks good:

Amazon, Etsy, Google and Facebook are all primarily software development shops which command enormous amounts of resources. They are, to use Christopher Little’s metaphor, unicorns. How can the rest of us adopt continuous delivery? That’s the subject of my talk, which describes four case studies of organizations that adopted continuous delivery, with varying degrees of success.

One of my favourites – partly because it’s embedded software, not a website – is the story of HP’s LaserJet Firmware team, who re-architected their software around the principles of continuous delivery. People always want to know the business case for continuous delivery: the FutureSmart team provide one in the book they wrote that discusses how they did it.
continuous-integration  continuous-delivery  build  release  process  dev  deployment  videos  qcon  towatch  hp 
may 2013 by jm
Performance Testing Java Applications [talk]
Martin "Disruptor" Thompson on performance testing.

This talk explores when to start performance testing, how to avoid the common pitfalls, how to profile when the results cause your team to pull a funny face, and what you can do about that funny face. Specific issues to Java and managed runtimes in general will be explored, but if other languages are your poison, don't be put off as much of the content can be applied to any development.
testing  performance  towatch  talks  video  slides  infoq  qcon 
march 2013 by jm
Extreme Performance with Java - Charlie Hunt [slides, PDF]
presentation slides for Charlie Hunt's 2012 QCon presentation, where he discusses 'what you need to know about a modern JVM in order
to be effective at writing a low latency Java application'. The talk video is at http://www.infoq.com/presentations/Extreme-Performance-Java
low-latency  charlie-hunt  performance  java  jvm  presentations  qcon  slides  pdf 
january 2013 by jm
InfoQ: Lock-free Algorithms
Michael Barker and Martin Thompson's talk at the last QCon on the LMAX Disruptor, and other nifty lock-free techniques and patterns. 'Martin Thompson and Michael Barker explain how Intel x86_64 processors and their memory model work, along with low-level techniques that help creating lock-free software.'
lock-free  locking  mutexes  algorithms  lmax  disruptor  infoq  slides  presentations  qcon  java 
april 2012 by jm
Cloud Architecture Tutorial - Platform Component Architecture (2of3)
Amazing stuff from Adrian Cockroft at last week's QCon. Faceted object model, lots of Cassandra automation
cassandra  api  design  oo  object-model  java  adrian-cockroft  slides  qcon  scaling  aws  netflix 
march 2012 by jm

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