1998210 - ObjectToSource is inefficient and can create very large output strings

Status: NEW

(Core :: JavaScript Engine, defect, P5)

Description

[Jon Coppeard (:jonco)]

This is not high priority as this is not really exposed to the web any more, but it is used when creating error messages which can be triggered from the web.

ObjectToSource is very inefficient. It creates creates tons of intermediate JSStrings as it builds up its output and this can cause unnecessary GC activity and take a long time.

Also the size of its output is also basically unbounded. Including multiple MBs of object representation in error messages is not useful.

For a situation where this can happen see the testcase in bug 1968172.

Ideally this would 1) use a JSStringBuffer to build up the result rather than creating JSStrings and concatenating them 2) allow a size limit on the output to be specified.