It would indeed be interesting to evaluate. The naive CC a= lgorithm does have a huge impact on memory, and i have the feeling that it&= #39;s often a choice of feasibility more than performance, meaning that oft= en the naive approach might not be a solution at all due to the huge memory= footprint.
Given that Pregel/Giraph is network-bound, my bet is that one more iteratio= n should be cheaper than lots of large messages.

On Tue, May 6, 2014 at 3:05 = PM, Dionysis Logothetis wrote:
Hi guys,

One o= f the ways we've thought about improving the clustering implementation = in the Okapi library (although we haven't implemented it yet) is the fo= llowing. In the naive implementation EVERY vertex sends its friend list to = ALL its neighbours. But, because in a triangle it's enough for just 1 o= f the vertices to detect the triangle, you can have a vertex send its frien= d list only to neighbors that have lower id. This way, the node with the lo= wer id in the triangle can detect the triangle and simply notify its neighb= ors that they belong to one (every vertex needs to know).

Now, I think this works only for undirected graphs and it ad= ds an extra iteration with respect to the naive implementation, but can pro= bably reduce the amount of traffic and memory used significantly.

By taking a quick look at the algorithm by Ediger= et al that Arun implemented, it uses a similar approach, that is, selectiv= ely propagating vertex ids. That one introduces more iterations, but probab= ly reduces the amount of traffic even more which can be very beneficial. It= could be interesting to compare these approaches.

On Tue, May 6, 2014 a= t 12:47 PM, Lukas Nalezenec wrote:
=20 =20 =20
Hi,
```It has been some time and I don't remember all my comm=
ents.  I think you can replace LongArrayListWritables with class that will =
sort numbers inside, make a diff compression and write variable length numb=
ers.
This might cut memory usage by 80~90% (depending on graph properties).
You could also reduce a number of memory allocations and use primitive coll=
ections.

Regards
Lukas

```

On 6.5.2014 09:08, Arun Kumar wrote:
=20
Hi

For Okapi ML library it is mentioned that some tuning should be done .Can you clarify that what modification we have to do?

Regards
Arun

On Tue, Mar 18, 2014 at 2:30 PM, Lukas Nalezenec wrote:
Hi,
Check Okapi ML library from Grafos:
http://grafos.ml/okapi.html#collaborative-als
It needs some tuning but it will work.

Regards
Lukas

On 17.3.2014 20:17, Suijian Zhou wrote:
Hi, Experts,
=C2=A0 Does anybody know if there are examples of implementation in giraph for clustering coefficient (counting triangles)? Thanks!

=C2=A0 Best Regards,
=C2=A0 Suijian

--
=C2=A0 =C2=A0Claudio Martella
=C2=A0 =C2=A0
--047d7bdc843a20b5b904f8bb886c--