Hadoop jobs are great to compute and aggregate tons of data. However, getting a feedback from batches can take up to hours depending on the workflow. In some contexts, a minute of latency to get the feedback can cost money. At Big Data Berlin on April 30th, Sofian talked about how Criteo switched from a batch-only architecture to a lambda architecture during our internal Hackathon.

1. From 6 hours to 1 minute... in 2 days!
How we managed to stream our (long)
Hadoop batches
1
Sofian DJAMAA - Software engineer
@sdjamaa

2. Phase 1 - Buy displays
Phase 2 - Sell clicks
Phase 3 - ???
Phase 4 - Profit
Criteo

3. How does it work?
What’s
on Bild website
today?
user
We gather the
information for the
retargeting process
Let’s go on
Amazon!!
The website
contains a
« pixel » used
to put
information
on the user
cookie
user
eCommerce
website
publisher
website
Using the
information we have
on the user, tagged
by a cookie, we
display the right ad
Advertiser side
Publisher side

4. HOW DO THEY
KNOOOOOOOOWW????

5. Our constraints
6 datacenters
!
3 billions events a day
!
+50 PB of data in our Hadoop cluster
!
800K HTTP requests/second
!
JIRA ticket generation

6. How do we use the data? Where’s my
money?
WHERE’S
MY F@*#
MONEY?!?!
Where’s my
client’s money?
finance
sales
business devinternal
reports
client
reports
billing
(heavy) data
transformation
clicks, displays,
purchases…
client
YAY!!
MAKIN’
MONEY!!
client dashboard
(web)

7. But this takes time…

8. Where goes the data? There’s
an issue… let’s
investigate
WTF?!?!?
business
escalation
relase
management
Data not aggregated cross-DC
!
Granularity limited due to the volume
of data
!
Load time can be huge even if we bulk
insert (or move files)
clicks, displays,
purchases…
IIS web
servers
SQL Server DBs
(multiple instances
per DC)
Graphite
monitoring
Scaling is limited therefore
only the most aggregated
level is kept in Graphite
production
alert

9. Up to 6 hours for some metrics
!
Volume being huge, processing and
storage takes time (SQL Server
replication hell…)
!
Multiple datacenters containing data
with latency issues

10. 6 hours to get business data
+ 1 hour to check data/raise alerts
+ 1 hour to find root cause
!
- SSome big money (up to million €)

11. finance
sales
release
management
(heavy) data
transformation
PBs of data to
replay
client
A lot of people need the same aggregated data but all with their own
constraints…
Consistency
required
Quick feedback

12. Batching on Hadoop or SQL Server
doesn’t fill the requirement
!
We need to have our checks as soon
as something wrong happens
!
We need to handle both real-time
and batch mode

13. But who can do it?

15. Some amazing projects such as:
!
- Ads in GIF format
!
- Embedded ad banners in movies
!
- Streaming service stopping several times a movie to display an ad
!
- Ponys
!
- And something about Chuck Norris (‘cause he’s awesome)
Internal hackathon

16. No team wanted to take the responsibility of project so we built our
own:
!
- 3 1/2 developers
!
- 1 business release manager (as a product owner)
!
- 2 business intelligence engineers (the guys that write SQL queries all day long)
!
- 1 business developer (doesn’t code a business layer obviously)
!
- 1 creative
!
- 1 release manager
!
- 1 technical solution guy (the guy who helps in putting the pixels)
Turbo

17. What people think a hackathon
is…

18. What really a hackathon is….

20. SummingBird computations
Metric aggregations at banner/zone level
- Clicks, displays, sales, revenue…
!
Real-time part
Aggregates are updated and sent after each event
30K messages/second
!
Batch part
Computes the expected trend of data for each period (reference data)
Using lasso: sum of squared errors, with a bound on the sum of the absolute
values of the coefficients

21. data processing is done in batches
on each side
when an offline batch is ready, it becomes the truth for the
whole system
online batches are computed in
streaming
batch #1 (e.g.
1H)
batch #2 batch #3
insert AND update
aggregated results
for each event
insert aggregated results
for 1 hour of events

22. λ =
http://github.com/twitter/summingbird

23. Platform[T]
def job = source.map { !
/* your job here */ "
}.store()
P#Source P#Store
job is
executed on
sends job results
to store
redirects input
to job

24. Why not streaming everything
then ?
Streaming costs a lot of infrastructure
!
Sometimes we need to replay (backfilling) events from the
past to correct a bug or adjust a formula
!
With PBs of data generated per day, a streaming
architecture needs to be massively parallelized (much
more than a batching architecture) for replays
!
Lambda Architecture is a good way to move towards a
full streaming architecture

25. Rule engine
Developed in Prolog
!
10K decisions/minute
!
Linked to the real-time flow to compute the
discrepancies with expected values and tag
abnormal data

26. Vizatra
In-house analytic visualization stack: world map, graphs, real-
time curves…
!
AngularJS, Bootstrap, Scala, Finagle, any DB supporting SQL
!
Web-component oriented: easy customization
!
Query deconstruction and NOT query building :-)
!
Open-source release coming soon

27. Riemann
Monitoring system with a « powerful stream processing
language » (nah, just Clojure configuration files)
!
Sends alerts based on tags sent by the rule engine
!
Scoped alerts
!
Alerts are emails and SMS to on-duty people
!
JIRA ticket generation

28. Awesomeness
✓ Data granularity
- Checks at banner/zone levels for
better investigations
✗ Data granularity
- Checks only at publisher website
level (only on RTB)
- No checks on the client side
✗ Latency up to 6 hours ✓ Latency of 1 minute
✗ Data aggregated hourly ✓ Data aggregated in 5-min period
✗ Money in the bank: $ ✓ Money in the bank: $$$$$

29. Even more…
Thanks to the hackathon, we are now able to provide real-time
feedback to sales, business developers, MDs and VPs which led
us to :
!
- Getting more clients as they love having a quick feedback on
their campaigns
!
- Adjust CPC in real-time
- For special occasions like sales
- To test aggressively our prediction models in an A/B test
!
- And more…

30. Some feedbacks
✗ Exponential learning curve with all frameworks
✗ A lot of features are missing (e.g. stores)
✗ Very limited documentation or tutorial
✗ Testing the error rate between Hadoop and Storm is
really too long for a 2 day development period
✗ Cassandra was a bad choice because of the data model
needed for the visualization part (lot of joins)

31. #Paris, #BigData, #MachineLearning, #NerfGuns, #Hadoop, #Storm, #Spark,
#Cassandra, #MongoDB, #Riemann, #Scala, #C# (?!), #Java
31
Sofian DJAMAA - Software engineer
@sdjamaa
WE RECRUIT!!!!
We have many open positions in the R&D:
!
• Data Processing Systems Manager
• Senior Software Engineer (Grenoble)
• Software Development lead/Manager
• SRE OPS Manager
• Senior Software Engineer – Palo Alto, CA.
• Python Software Lead Engineer - Paris
• Software Development Engineer –Paris
• Machine Learning Scientist