Bug 49050

Summary:	[PATCH] Inefficient concatenation of ContinueRecord contents in AbstractEscherHolderRecord
Product:	POI	Reporter:	Trejkaz (pen name) <trejkaz>
Component:	HSSF	Assignee:	POI Developers List <dev>
Status:	RESOLVED FIXED
Severity:	major	Keywords:	PatchAvailable
Priority:	P2
Version:	3.5-FINAL
Target Milestone:	---
Hardware:	All
OS:	All
Attachments:	Proposed patch Proposed patch

Description Trejkaz (pen name) 2010-04-06 03:49:05 UTC

We encountered a spreadsheet with a lot of drawings in it, which resulted in a DrawingGroupRecord which was so large it had multiple separate ContinueRecord entries to make up all its data.

Subsequently, the gradual growing of the byte array as these were encountered became a performance issue, with the file taking around 20 minutes to load.

I can't provide a sample file, but I will provide a patch which reduces this case to around 3 seconds.

Comment 1 Trejkaz (pen name) 2010-04-06 03:52:15 UTC

Created attachment 25231 [details]
Proposed patch

Proposed patch fixes the issue for that specific record type.

I took a look at some other record types (e.g. DrawingRecord.)  A lot of them assume a single ContinueRecord and indeed I haven't seen a case of them having more than one.  But in the event that one day they do, this solution would work there as well.

Another thing I noticed is that other record types explicitly keep the ContinueRecord data separate and serialise it separately, whereas with EscherDrawingRecord this was not the case.  This may not be a problem though, I just thought it was worth noting.

Comment 2 Trejkaz (pen name) 2010-04-06 04:33:32 UTC

Created attachment 25232 [details]
Proposed patch

Newer version after our own review.

Comment 3 Nick Burch 2010-05-05 12:46:41 UTC

Thanks for the patch, applied in r941379.