id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
20405	[Patch] History browser for complex relations requires lots of memory	GerdP	GerdP	"==== What steps will reproduce the problem?
1. Browse history of !r2795128 (EuroVelo 3 - Pilgrim's Route - part Germany), a relation with > 1200 versions and > 4600 members 
2. Open e.g. VisualVm to create and analyse a heapdump
==== What is the expected result?
No (additional) instances for RelationMemberData as the dialog doesn't show any member specific data
==== What happens instead?
5.345.959(!) instances of `RelationMemberData` which require ~244 MB 
The single instance of `HistoryRelation` retains ~300MB.
==== Please provide any additional information below. Attach a screenshot if possible.
I think it would be better to wait for the use to actually select the members tab before we create instances of `RelationMemberData`. Should not take too long when the corresponding changeset files were downloaded and cached.

{{{
URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-12-28 22:03:23 +0100 (Mon, 28 Dec 2020)
Build-Date:2020-12-30 02:30:55
Revision:17428
Relative:URL: ^/trunk

Identification: JOSM/1.5 (17428 en) Windows 10 64-Bit
OS Build number: Windows 10 Home 2004 (19041)
Memory Usage: 1414 MB / 3641 MB (1083 MB allocated, but free)
Java version: 1.8.0_221-b11, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Look and Feel: com.sun.java.swing.plaf.windows.WindowsLookAndFeel
Screen: \Display0 1920×1080 (scaling 1.00×1.00)
Maximum Screen Size: 1920×1080
Best cursor sizes: 16×16→32×32, 32×32→32×32
VM arguments: [-XX:StartFlightRecording=name=MyRecording2,settings=d:\dbg\gerd.jfc, -XX:FlightRecorderOptions=defaultrecording=true,dumponexit=true,dumponexitpath=e:\ld\perf_20210119_072729.jfr]

Plugins:
+ ColumbusCSV (35640)
+ buildings_tools (35669)
+ o5m (35640)
+ pbf (35650)
+ poly (35640)
+ reltoolbox (35640)
+ reverter (35688)
+ undelete (35640)
+ utilsplugin2 (35682)

Validator rules:
+ c:\josm\core\resources\data\validator\geometry.mapcss
}}}
"	enhancement	closed	normal	24.01	Core		fixed	template_report history performance	Don-vip