Janino

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: None
• Fix Version/s: None
• Component/s: None
• Labels:

  None
• Environment:

  Any

Janino currently uses repeated calls to the String.concat() method to implement the concatenation of strings using the + operator. While this is certainly optimal in the case of two operands, larger numbers of operands result in degraded performance (due to the resulting quadratic complexity). Though Janino performs a 'constant folding' optimization that resolves this in many/most instances, the performance of non-constant concatenation is still a problem.

A test case can be dowloaded from:
http://www.tomgibara.com/janino-evaluation

A preliminary benchmark comparing the performance of concat() to StringBuffers and StringBuilders in Java 1.5 and Java 6 might be useful and is available at:
http://www.tomgibara.com/janino-evaluation/string-concatenation-benchmark

Note this behaviour has been observed in Janino versions 2.5.1 - 2.5.3 inclusive, but is probably present in all versions.

• Assignee:

  Arno Unkrig

  Reporter:

  Tom Gibara

• Created:

  02/Feb/07 2:12 PM

  Updated:

  15/Feb/07 2:06 PM

  Resolved:

  15/Feb/07 2:06 PM