[SPARK-32578] PageRank not sending the correct values in Pergel sendMessage

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Invalid
• Affects Version/s: 2.3.0, 2.4.0, 3.0.0
• Component/s: GraphX
• Assignee: Unassigned
• Reporter: Shay Elbaz
• Created: 10/Aug/20 06:20
• Updated: 15/Sep/20 08:16
• Resolved: 15/Sep/20 08:16

Description

The core sendMessage method is incorrect:

def sendMessage(edge: EdgeTriplet[(Double, Double), Double]) = {
 if (edge.srcAttr._2 > tol) {
   Iterator((edge.dstId, edge.srcAttr._2 * edge.attr))
                          // *** THIS ^ ***
 } else {
   Iterator.empty
 }
}

 

Instead of using the source PR value, it's using the PR delta (2nd tuple arg). This is not the documented behavior, nor a valid PR algorithm AFAIK.

This is a 7 years old code, all versions affected.