05 July 2011, 16:22

Firefox developers locate a source of bloat

Firefox Aurora Firefox developers have been hunting down memory issues in Firefox and appear to have located a major one in the JavaScript engine. It appears, according to the bug report, that memory was fragmenting within the JavaScript engine due to it keeping 1MB chunks alive for long living system objects.

The developers then created a patch to reduce fragmentation by taking account of system objects and the results were described as "ridiculously good". In the test, memory usage without the patch was measured at around 239 MB and with the patch at 189 MB; after running "minimise memory usage", the unpatched Firefox was using 108 MB while the patched version was using only 21 MB, five times better. Together with a fix for bug 656120 – which will see the TraceMonkey JavaScript engine running garbage collection far more frequently – these changes should see Firefox consuming less memory.

The changes though will only appear in Firefox 7; Firefox 6 is about to go beta, so Firefox 7 is the earliest the modifications can appear; Firefox 7 is due to arrive in the Aurora channel at the same time as 6 goes beta.

(djwm)

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