Bug 75610

Summary: push/shift fifo may consume excessive memory
Product: WebKit Reporter: Gavin Barraclough <barraclough>
Component: JavaScriptCoreAssignee: Nobody <webkit-unassigned>
Status: RESOLVED FIXED    
Severity: Normal CC: dglazkov, webkit.review.bot
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 75140    
Attachments:
Description Flags
Fix sam: review+, webkit.review.bot: commit-queue-

Gavin Barraclough
Reported 2012-01-05 01:05:48 PST
Array object commonly store data in a vector, consisting of a portion that is in use, a pre-capacity (m_indexBias) and a post-capacity (the delta between m_length and m_vectorLength). Calls to shift with grow the pre-capacity, and the current algorithm for increaseVectorLength (used by push, or [[Put]]) will never shrink the pre-capacity, so a push/shift fifo may consume an inordinate amount of memory, whilst having a relatively small active length.
Attachments
Fix (4.45 KB, patch)
2012-01-05 01:13 PST, Gavin Barraclough 		sam: review+
webkit.review.bot: commit-queue-
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Gavin Barraclough
Comment 1 2012-01-05 01:13:17 PST
Created attachment 121237 [details] Fix 10% overall speedup on the micro-benchmark attached to bug #75588 , largely due to a 20x speedup on the two smaller fifo tests (I think this makes sense - they'll currently be serving as tests for the OS's memory allocation speed!)
WebKit Review Bot
Comment 2 2012-01-05 09:40:03 PST
Comment on attachment 121237 [details] Fix Attachment 121237 [details] did not pass chromium-ews (chromium-xvfb): Output: http://queues.webkit.org/results/11146007 New failing tests: http/tests/inspector/network/download.html
Gavin Barraclough
Comment 3 2012-01-05 11:19:24 PST
(In reply to comment #2) > (From update of attachment 121237 [details]) > Attachment 121237 [details] did not pass chromium-ews (chromium-xvfb): > Output: http://queues.webkit.org/results/11146007 > > New failing tests: > http/tests/inspector/network/download.html Works for me, and this bug doesn't affect Chromium. Bad EWS.
Gavin Barraclough
Comment 4 2012-01-05 11:35:28 PST
Fixed in 104184.
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