BigDecimal performance notes

Anders — Wed, 04 Jun 2008 13:47:00 -0400

Notes on java.math.BigDecimal’s performance (in Java 1.5):

Sorting

BigDecimal’s compareTo method relies on both of the BigDecimals being in the same internal form. Internally BigDecimal uses either a BigInteger or, when possible, a native integer to represent its value. To compare two BigDecimals they’re both normalized (“inflated”) to the BigInteger form. This means that simply sorting a list of BigDecimals can cause memory use to increase. Not what you’d expect.

Serialization

Serialization of BigDecimal is surprisingly slow. Not only do they inflate their internal representation, just like when comparing, but they also use a lot of CPU for some reason. When serializing large graphs of objects of a lot of different classes, the BigDecimals stood out like a sore thumb in the CPU profile. Dumping them as String representations instead was quicker and didn’t use as much memory.

A View From Above: Tag performance

BigDecimal performance notes

Sorting

Serialization