I suggest you store this information as a property of the vertex. If its just a flag, you could use a BooleanWritable. That would be the V in <I, V, E>.
________________________________ From: Sardeshmukh, Vivek [vivek-sardeshm...@uiowa.edu] Sent: Monday, July 21, 2014 2:05 PM To: user@giraph.apache.org Subject: Setting variable value in Compute class and using it in the next superstep Hi, all-- In my algorithm, I need to set a flag if certain conditions hold (locally at a vertex v). If this flag is set then execute some other block of code *only once*, and do nothing until some other condition is hold. My question is, can I declare a flag variable in the class where I override compute function? I defined the flag as a public variable and setting it once the conditions are met but it seems the value is not "carried" over to the next superstep. I dig a little bit in this mailing list and found this https://www.mail-archive.com/user@giraph.apache.org/msg01266.html This post also suggests (along with what I described above) to have a field in the vertex value itself. For that I need to change the vertex input format and also create my own custom vertex class. Is it really necessary? By the way, I am using Giraph 1.1.0 compiled against Hadoop 1.0.3. I was able to run SimpleShortestPathComputation successfully. Here are more technical details of my algorithm: I am trying to implement Delta-stepping shortest path algorithm ( http://dl.acm.org/citation.cfm?id=740136 or http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.46.2200 ). This was mentioned in Pregel paper. A vertex "relax" light edges if it belongs to the minimum bucket index (of course, aggregators!). Once a vertex is done with relaxing light edges it relaxes heavy edges (here is where I need a flag) once. A vertex may be "re-inserted" to a newer bucket and may have to execute all the steps that I described here again. Thanks. Sincerely, Vivek A beginner in Giraph (and Java too!)
