[TRINIDAD-906] optimize getClientId - use per thread shared StringBuilder

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.2.5-core
• Fix Version/s: 1.0.6-core, 1.2.6-core
• Assignee: Gabrielle Crawford
• Reporter: Gabrielle Crawford
• Created: 18/Jan/08 23:59
• Updated: 27/Jan/10 08:45
• Resolved: 19/Jan/08 00:20

Description

In getClientId/getContainerClientId we create a new stringBuilder.

However when creating a client id we only use one stringBuilder at a time, so have a single instance of a StringBuilder saved on thread local.

Have a utility to get this instance, and any time a user gets the instance, set the length of the stringBuilder to 0. This will completely break if a user tries to call it for 2 stringbuilders, so doc this well.

Preliminary testing by a performance person here at Oracle found "the saving is ~300KB out of 5850KB for the request. This is about 5% total request memory. As expected profile shows that most of the memory saving comes from not creating huge number of string builders"