id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
15547	Serious autocomplete performance degradation	SafwatHalaby	Don-vip	"== Intro ==

I deal with a huge dataset (about 30k bus stops nodes) almost daily.
This was never a problem before, but since recently, JOSM often hangs when I edit the bus stop tags.
Waiting for a few seconds (can be up to ~30) always resolves this.

It happens seems to happen when editing massively used keys. For instance, all stops have a
""ref"" key, and when I click ""edit"" on a single stop's ""ref"", JOSM
stalls. A similar issue occurs when adding ""description"" to changeset
uploads. Description is also used by all stops. So it appears this is triggered whenever auto-complete is in use.

== Profiling ==

""I can reproduce this locally on JOSM 13106. According to jvisualvm cpu
profiling (on Oracle JDK), most time is spent in method
org.openstreetmap.josm.data.tagging.ac.AutoCompletionSet.add""
-- mmd


It's a CPU starvation issue and not a memory overuse issue. 
(Core at 100% for 10-30 seconds).

== Test case ==
Run the Overpass query below to obtain a huge bus stop dataset, then try editing the ref or name of a stop.
12712 works flawlessly.
13053 hangs for 10-30 seconds.

== Query ==
{{{
#!css
[out:xml][timeout:90][bbox:29.4013195,33.8818359,33.4131022,36.0791016]
;
(
area(3601473946); // Israel
area(3601803010); // Judea and Samaria district
)->.a;
(
  node[""highway""=""bus_stop""](area.a);
  way[""highway""=""bus_stop""](area.a);
)->.b;
(rel(bw.b);rel(bn.b))->.routes;
(.b;way(bn.b);)->.b;
(.b;node(w.b);)->.b;
(.b;.routes;);
out meta;
}}}

== Status report ==

{{{
URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2017-09-02 14:47:18 +0200 (Sat, 02 Sep 2017)
Build-Date:2017-09-02 20:53:16
Revision:12712
Relative:URL: ^/trunk

Identification: JOSM/1.5 (12712 en) Linux Debian GNU/Linux 9.2 (stretch)
Memory Usage: 468 MB / 811 MB (227 MB allocated, but free)
Java version: 1.8.0_141-8u141-b15-1~deb9u1-b15, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1366x768
Maximum Screen Size: 1366x768
Java package: openjdk-8-jre:amd64-8u141-b15-1~deb9u1
Java ATK Wrapper package: libatk-wrapper-java:all-0.33.3-13
Dataset consistency test: No problems found
}}}

Nothing fancy installed, everything is default. No extra plugins, validator rules, map paint styles, presets, etc."	defect	closed	major	17.11	Core		fixed	regression performance