28 May
2014
28 May
'14
6:02 p.m.
Thomas,
thanks for your fast response. My comments are below.
On 05/28/14 05:27 PM, Thomas Mortagne wrote:
You are mixing several things here. It's not
because you hit Out of
memory errors that you have a memory leak, it can simply mean that you
have a document cache too big for the memory you allocated for
example. You can modify the documents cache size in xwiki.cfg.
I see two caches in that file:
xwiki.store.cache
xwiki.render.cache
both seems to be commented out.
How much memory did you allocated ? XWiki is not a
small beast and it
require a minimum to work. See
http://platform.xwiki.org/xwiki/bin/view/AdminGuide/Performances#HMemory.
To prevent misunderstanding. I've not set any limit on memory etc. I
just simply use xwiki-enterprise-jetty-hsqldb-6.0.1.zip as distributed
on xwiki.org. This distro does have 512MB RAM cap which following your
link above should be good for medium installs.
The question is, if the value of caches above are commented out in
xwiki.cfg, then what are actual default values which are used in the
xwiki-enterprise-jetty-hsqldb-6.0.1.zip distro? Just to know from which
value I shall go lower...
Thanks!
Karel
On Wed, May 28, 2014 at 4:58 PM, Karel Gardas<karel.gardas(a)centrum.cz> wrote:
Folks,
I'm testing kind of scalability of XWiki by simple benchmark which creates N
pages in a loop (one page at a time, it's not parallel run!) and then when
this loop finishes, it again in another loop gets all the pages from the
server (again serially, one page at the time). For page creation we're using
REST API, for getting the pages we're using common browseable URL
(/xwiki/bin/view/...).
Now the problem is that if I try to attempt creation of 100k pages, then I
hit Java's out of memory errors and server is unresponsive from that time.
I've tested this on:
- xwiki-jetty-hsql-6.0.0
- xwiki-jetty-hsql-6.0.1
- xwiki-tomcat7-pgsql -- debian xwiki packages running on top of debian 7.5
Of course I know the way how to increase Java's memory space/heap space. The
problem is that this will not help here. Simply if I do so and then create
100 millions of pages on one run I will still get to the same issue just
it'll take a lot longer.
I've googled a bit for memoryleaks issues on Java and found an interesting
recommendation to use parallel GC. So I've changed start_xwiki.sh to include
-XX:+UseParallelGC in XWIKI_OPTS
Anyway, the situation is still looking suspiciously. I've connected JConsole
to the xwiki java process and overall view looks:
https://app.box.com/s/udndu96pl2fvuz3igvor
this is whole run overview, but perhaps even more clear is it on last 2
hours view which is here:
https://app.box.com/s/deuix33fzejra4uur941
Sidenote this all is from debugging xwiki-jetty-hsql-6.0.1 distro.
Now, what worries me a lot is this bottom cap which is growing. You can see
that clearly in Heap Memory Usage from 15:15. In CPU usage you can also see
that around the same time the CPU consumption went up from ~15% to ~45%
When I switch to Memory Tab in JConsole and click several times on "Perform
GC" button, the bottom cap is still there and I cannot get lower in memory
usage. With this going on I can also see server failing after some time on
OOM error.
Any help with this is highly appreciated here.
Thanks!
Karel
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