  We present a new record on computing specific bits of Pi, the mathematical
constant, and discuss performing such computations on Apache Hadoop clusters.
The specific bits represented in hexadecimal are 0E6C1294 AED40403 F56D2D76
4026265B CA98511D 0FCFFAA1 0F4D28B1 BB5392B8. These 256 bits end at the
2,000,000,000,000,252nd bit position, which doubles the position and quadruples
the precision of the previous known record. The position of the first bit is
1,999,999,999,999,997 and the value of the two quadrillionth bit is 0. The
computation is carried out by a MapReduce program called DistBbp. To
effectively utilize available cluster resources without monopolizing the whole
cluster, we develop an elastic computation framework that automatically
schedules computation slices, each a DistBbp job, as either map-side or
reduce-side computation based on changing cluster load condition. We have
calculated Pi at varying bit positions and precisions, and one of the largest
computations took 23 days of wall clock time and 503 years of CPU time on a
1000-node cluster.
