Well...
after various tests I downgraded to lucene 1.9.1 to see if that had
any effect... doesn't seem that way.
I have set up a JMeter test with 5 concurrent users doing a search (a
silly search for a two letter word) every 3 seconds (with a random of
+/- 500ms).
- With 512 MB xms/xmx memory usage settles between 400/500 after a few
iterations, but no OOME.
At the end of the run memory settles usually between 200-300 somewhere
(really depends), but no cleanup occurs for minutes ...unless I do a
forced GC.
- Did the same run with 384MB and hit 2 OOME
- Did the same run with 256MB and hit 5 or 6 OOME
Tried to run tomcat with jdk 1.6 and -server option as well, but
didn't seem to help at all either.
The finally I ran the test scenario above but with 1536MB xms/xmx...
and guess what. It used it all pretty quickly. It used between
1000-1400/1500 for most of the run. At the end of the run memory usage
settled at about 750 MB ... until I did a forced gc.
This do bother me, if the solution could have been to throw more
memory at the problem I could live with that, but it just seems to
consume all memory it can get it hands on (:-
Is there any way to limit the memory usage in Lucene (configuration) ?
Im obviously not sure if lucene is the culprit as Im using spring
(2.5) , hibernate (3.3) and open session in view and lots of other
stuff etc in my app. So I guess my next step would be to create a very
limited web app with just a servlet calling the lucene api.Then do
some profiling on that.
cheers
Magnus
On 3. des.. 2008, at 14.45, Michael McCandless wrote:
Are you actually hitting OOME?
Or, you're watching heap usage and it bothers you that the GC is
taking a long time (allowing too much garbage to use up heap space)
before sweeping?
One thing to try (only for testing) might be a lower and lower -Xmx
until you do hit OOME; then you'll know the "real" memory usage of
the app.
Mike
Magnus Rundberget wrote:
Sure,
Tried with the following
Java version: build 1.5.0_16-b06-284 (dev), 1.5.0_12 (production)
OS : Mac OS/X Leopard(dev) and Windows XP(dev), Windows 2003
(production)
Container : Jetty 6.1 and Tomcat 5.5 (latter is used both in dev
and production)
current jvm options
-Xms512m -Xmx1024M -XX:MaxPermSize=256m
... tried a few gc settings as well but nothing that has helped
(rather slowed things down)
production hw running 2 XEON dual core processors
in production our memory reaches the 1024 limit after a while (a
few hours) and at some point it stops responding to forced gc
(using jconsole).
need to digg quite a bit more to figure out the exact prod
settings. But safe to say the memory usage pattern can be recreated
on different hardware configs, with different os's, different 1.5
jvms and different containers (jetty and tomcat).
cheers
Magnus
On 3. des.. 2008, at 13.10, Glen Newton wrote:
Hi Magnus,
Could you post the OS, version, RAM size, swapsize, Java VM version,
hardware, #cores, VM command line parameters, etc? This can be very
relevant.
Have you tried other garbage collectors and/or tuning as described
in
http://java.sun.com/javase/technologies/hotspot/gc/gc_tuning_6.html?
2008/12/3 Magnus Rundberget <[EMAIL PROTECTED]>:
Hi,
We have an application using Tomcat, Spring etc and Lucene 2.4.0.
Our index is about 100MB (in test) and has about 20 indexed fields.
Performance is pretty good, but we are experiencing a very high
usage of
memory when searching.
Looking at JConsole during a somewhat silly scenario (but
illustrates the
problem);
(Allocated 512 MB Min heap space, max 1024)
0. Initially memory usage is about 70MB
1. Search for word "er", heap memory usage goes up by 100-150MB
1.1 Wait for 30 seconds... memory usage stays the same (ie no gc)
2. Search by word "og", heap memory usage goes up another 50-100MB
2.1 See 1.1
...and so on until it seems to reach the 512 MB limit, and then a
garbage
collection is performed
i.e garbage collection doesn't seem to occur until it "hits the
roof"
We believe the scenario is similar in production, were our heap
space is
limited to 1.5 GB.
Our search is basically as follows
----------------------------------------------
1. Open an IndexSearcher
2. Build a Boolean Query searching across 4 fields (title,
summary, content
and daterangestring YYYYMMDD)
2.1 Sort on title
3. Perform search
4. Iterate over hits to build a set of custom result objects
(pretty small,
as we dont include content in these)
5. Close searcher
6. Return result objects.
You should not close the searcher: it can be shared by all queries.
What happens when you warm Lucene with a (large) number of
queries: do
things stabilize over time?
A 100MB index is (relatively) very small for Lucene (I have indexes
100GB). What kind of response times are you getting, independent of
memory usage.
-glen
We have tried various options based on entries on this mailing
list;
a) Cache the IndexSearcher - Same results
b) Remove sorting - Same result
c) In point 4 only iterating over a limited amount of hits rather
than whole
collection - Same result in terms of memory usage, but obviously
increased
performance
d) Using RamDirectory vs FSDirectory - Same result only initial
heap usage
is higher using ramdirectory (in conjuction with cached
indexsearcher)
Doing some profiling using YourKit shows a huge number of char[],
int[] and
string[], and ever increasing number of lucene related objects.
Reading through the mailing lists, suspicions are that our
problem is
related to ThreadLocals and memory not being released. Noticed
that there
was a related patch for this in 2.4.0, but it doesn't seem to
help us much.
Any ideas ?
kind regards
Magnus
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