Thanks Otis!
I think I now got a clearer picture of the issue and its causes, thanks.
Could you please elaborate on "warming up" searcher prior exposure to real
requests, does this mean running through as many most often used queries as
possible such that results are cached, and also use as much cache as
possible?
Thanks!
--------------------------------------------------
From: "Otis Gospodnetic" <[EMAIL PROTECTED]>
Sent: Wednesday, February 06, 2008 1:09 PM
To: <solr-user@lucene.apache.org>
Subject: Re: how to improve concurrent request performance and stress
testing
Imagine this type of code:
synchronized (someGlobalObject) {
// search
}
What happens when 100 threads his this spot? The first one to get there
gets in and runs the search and 99 of them wait.
What happens if that "// search" also involves expensive operations, lots
of IO, warming up, cache population, etc? Those 99 threads will have to
wait a while.... :)
That's why it is recommended to warm up the searcher ahead of time before
exposing it to real requests. However, even if you warm things up, that
sync block will remain there, and at some point this will become a
bottleneck. What that point is depends on the hardware, index size, query
complexity and rat, even JVM.
Otis
--
Sematext -- http://sematext.com/ -- Lucene - Solr - Nutch
----- Original Message ----
From: Ziqi Zhang <[EMAIL PROTECTED]>
To: solr-user@lucene.apache.org
Sent: Wednesday, February 6, 2008 6:37:40 PM
Subject: Re: how to improve concurrent request performance and stress
testing
Thanks
Yonik,
>
It
uses
a
thread
per
request,
simultaneously
(up
to
any
limit
>
configured
by
the
app
server)
How
can
I
change
this
setting
then?
I
suppose
it
is
to
do
with
Jetty
or
Tomcat
whichever
hosts
solr
application,
not
through
the
solrconfig?
I
still
do
not
understand
why
sending
100
request
(of
same
query)
from
100
threads
throws
solr
server
to
silence
-
is
it
because
of
the
computational
cost
to
deal
with
same
query
in
100
separate
threads?
I
noticed
that
disabling
facet
counts
improves
things
a
bit,
but
not
significant.
Thanks
in
advance!
