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| Guest |
 Posted: Fri Jun 18, 2010 9:42 pm |
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| cstar |
| Posted: Sun Jun 20, 2010 4:22 pm |
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Joined: 05 Jan 2009
Posts: 4
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Hi Karthik,
Several notes : |
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| Guest |
| Posted: Tue Jun 22, 2010 7:34 pm |
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| Posted: Tue Jun 22, 2010 7:46 pm |
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Joined: 05 Jan 2009
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| Guest |
| Posted: Thu Jul 01, 2010 2:41 am |
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Guest
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I've been doing more load testing, this is what I've learned.
The bottlenecking in mod_muc is not actually a flaw in the mod_muc process itself, I was wrong to assume that, and the fprof analysis was misleading because fprof itself slowed the system down so much. |
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| Guest |
| Posted: Thu Jul 01, 2010 3:55 am |
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Guest
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01.07.2010 12:40, Karthik Kailash wrote:
> *Finally I found the source of ejabberd_router:route's occasional extreme
> slowness is a single mnesia call in ejabberd_sm:do_route.* The line is:
> mnesia:dirty_index_read(session, USR, #session.usr). Sampling using
> timer:tc every few thousand messages, I found that 80-90% of the time, this
> call is fast (< 100 us), but the remaining 10-20% it takes tens of ms to
> complete. This is exactly the same as the ejabberd_router:route behavior.
>
> So I'm pretty certain I've narrowed the bottleneck problem down to this
> line. However, the session table is in RAM and there is an index on the usr
> field, so I can't figure out why this problem is happening!
>
> Any thoughts or ideas?
Hello, Karthik. First of all, your investigation is interesting 
However, I cannot reproduce the issue. This is how I reproduce it:
1) Connect with 2 clients and join to some muc conference.
2) Start eprof on the room pid.
3) Route messages from one of the connected users to the room in erlang
shell:
> lists:foreach(fun(_) -> ejabberd_router:route(jlib:make_jid("user",
"domain.com", "resource"), jlib:make_jid("room",
"conference.domain.com", ""), {xmlelement, "message", [{"type",
"groupchat"}], [{xmlelement, "body", [], [{xmlcdata, "a"}]}]}) end,
lists:seq(1, 1000)).
4) Analyze eprof data.
According to your report, there should be
mod_muc_room:process_groupchat_message (and maybe some mnesia functions)
in the top of eprof output, but I don't see this.
On the other hand, according to your symptoms and looking into mnesia
sources I've found that dirty functions call to mnesia:do_dirty_rpc/5
function, which calls rpc:call, here is a snippet:
do_dirty_rpc(Tab, Node, M, F, Args) ->
case rpc:call(Node, M, F, Args) of
{badrpc, Reason} ->
timer:sleep(20), %% Do not be too eager, and can't use yield on SMP
...
do_dirty_rpc(Tab, NewNode, M, F, Args)
This might be a problem in your case. Try to add debug output there to
check if you don't get {badrpc, Reason} in this function.
--
Regards,
Evgeniy Khramtsov, ProcessOne.
xmpp:xram@jabber.ru.
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| Guest |
| Posted: Thu Jul 01, 2010 6:28 am |
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Guest
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Hi Evgeniy,
Quote: Hello, Karthik. First of all, your investigation is interesting However, I cannot reproduce the issue. This is how I reproduce it:
Thanks!
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| Guest |
| Posted: Thu Jul 01, 2010 6:37 am |
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Guest
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01.07.2010 16:27, Karthik Kailash wrote:
> Also I'm using the ejabberd 2.1.4 source, are you using the same?
Yes, more or less 
> I'd be happy to share my Tsung script and my modified ejabberd source
> files.
That would be great. If the problem is not in do_dirty_rpc/5, then just
post the script here, so I can borrow it and try in spare time.
--
Regards,
Evgeniy Khramtsov, ProcessOne.
xmpp:xram@jabber.ru.
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ejabberd@jabber.ru
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| Guest |
| Posted: Thu Jul 01, 2010 6:49 am |
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Guest
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| Ejabberd 2.1.4 comes with mnesia 4.4.5, but Erlang R13B03 has mnesia 4.4.12. |
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| Guest |
| Posted: Thu Jul 01, 2010 6:55 am |
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Guest
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01.07.2010 16:49, Karthik Kailash wrote:
> Ejabberd 2.1.4 comes with mnesia 4.4.5,
What do you mean? Ejabberd doesn't rely on mnesia version and doesn't
have mnesia sources. Or do you use binary installer?
> but Erlang R13B03 has mnesia 4.4.12.
> Is there a difference to use one or the other?
No idea.
--
Regards,
Evgeniy Khramtsov, ProcessOne.
xmpp:xram@jabber.ru.
_______________________________________________
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ejabberd@jabber.ru
http://lists.jabber.ru/mailman/listinfo/ejabberd
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| Guest |
| Posted: Thu Jul 01, 2010 7:03 am |
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Guest
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On Wed, Jun 30, 2010 at 11:54 PM, Evgeniy Khramtsov <xramtsov@gmail.com (xramtsov@gmail.com)> wrote:
Quote: 01.07.2010 16:49, Karthik Kailash wrote:
Quote: Ejabberd 2.1.4 comes with mnesia 4.4.5,
What do you mean? Ejabberd doesn't rely on mnesia version and doesn't have mnesia sources. Or do you use binary installer?
I used the binary installer.
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| Guest |
| Posted: Thu Jul 01, 2010 8:46 pm |
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Guest
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| On Wed, Jun 30, 2010 at 11:36 PM, Evgeniy Khramtsov |
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| Guest |
| Posted: Wed Jul 07, 2010 4:15 am |
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| Guest |
| Posted: Wed Jul 07, 2010 4:26 am |
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Here’s the Tsung configuration file.
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| Guest |
| Posted: Wed Jul 07, 2010 4:35 am |
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