Graph Processing & Bulk Synchronous Parallel Model

: public Vertex {
void Compute(MessageIterator* msgs) {
int mindist = IsSource(vertex_id()) ? 0 : INF;
Single Source Shortest Paths
for (; !msgs->Done(); msgs->Next())
mindist = min(mindist, msgs->Value());
if (mindist < GetValue()) {
class ShortestPathVertex *MutableValue() = mindist;
: public Vertex {
All VerFces tional iniFalized edge to can INF be
ad
OutEdgeIterator iter = GetOutEdgeIterator();
void Compute(MessageIterator* msgs) {
implemented a random
for (; !iter.Done(); iter.Next())
int mindist = IsSource(vertex_id()) SendMessageTo(iter.Target(),
? 0 : INF;
and a maximum-weig
for (; !msgs->Done(); msgs->Next())
mindist + iter.GetValue());
describe the former h
mindist = min(mindist, msgs->Value());
if (mindist < GetValue()) {
}
In the Pregel impl
Distance to source
tex value is a tuple o
*MutableValue() = mindist; VoteToHalt();
OutEdgeIterator iter = } GetOutEdgeIterator();
set the vertex is in (L
for (; !iter.Done(); }; iter.Next())
vertex once known.
SendMessageTo(iter.Target(),
carry no information)
mindist + iter.GetValue());
Edge algorithm Weight proceeds in
}
Figure 5: Single-source index shortest is justpaths.
the supe
VoteToHalt();
handshake.
}
};
class MinIntCombiner : public Combiner In phase 0{
of a cy
virtual void Combine(MessageIterator* sends a message msgs) { to ea
int mindist = INF;
and then unconditiona
Figure 5: Single-source for shortest (; !msgs->Done(); paths. msgs->Next()) (because it is already
mindist = min(mindist, msgs->Value());
or if all the message
class MinIntCombiner : public Combiner Output("combined_source", {
mindist); never be reactivated.
virtual void Combine(MessageIterator* }
msgs) {
in two supersteps and
int mindist = INF; };
In phase 1 of a cyc
for (; !msgs->Done(); msgs->Next())
randomly chooses on
mindist = min(mindist, msgs->Value());
Lecture
Output("combined_source",
14 : 590.02 Spring 13
mindist);
18 message granting tha