/usr/lib/lwp in Solaris 8

Question

Okay, I have seen earlier posts that suggests to put /usr/lib/lwp in front
of your LD_LIBRARY_PATH for Solaris 8 and for JDK 1.3.1. A lot have said
that increased the performance by 10 to 20%.
From what I can see, this will effectively use libthread.so in /usr/lib/lwp
instead of the the shared library with the same name in /usr/lib.
What is the difference between those two shared libraries? My understanding
that Solaris always uses lwp ( light-weight processes .. many-to-many ) by
default anyway, so I am curious as to what the directory name "lwp" mean.
Will BEA support this if you change the LD_LIBRARY_PATH?
Thanks,
John

Answer 1

OK, I can see how you might have concluded that this would be most
useful with fewer threads, but actually the only downside to using the
alternate threads library would be if you are creating many short lived
threads. The reason is that creating a bound thread is 4-5 times slower
than creating an unbound one. However, WebLogic recommends pooling user
created thread anyway, so this should not be an issue. You won't likely
notice the extra system overhead associated with the extra kernel
threads and LWPs plus Solaris will most likely manage the thread
scheduling much better than the JVM will.
-Charlie
Charlie Therit wrote:
I'm not sure how you came to the conclusion that it would be best used
where fewer threads are involved. The performance differences will
best measured with load test tools that measure throughput. However,
you should see differences in the JVM LWP/thread allocation by using
the ps command's -L options and/or pstack. You should also detect
differences in CPU utilization with vmstat/mpstat in that you may
reach higher utilization levels with less system overhead.
And yes, BEA does recommend this configuration and will support it.
-Charlie
"Jesus M. Salvo Jr." wrote:
Thanks. It's more clear now. So it seems like it is best used for
apps with
few threads.
Will / Does BEA support WebLogic Server using this thread library?
Raja Mukherjee wrote:
Jesus,
From Dimitri and Joel you already got the information you needed.The
official SUN reply can be found in
http://supportforum.sun.com/freesolaris/techfaqs.html?techfaqs_2957
Hope this helps...
.raja
"Jesus M. Salvo Jr." <[email protected]> wrote in message
news:[email protected]...
Yup, that was the thread I was referring to .... but still not
clear what
the difference in really technical details between libthread.soin
/usr/lib
and in /usr/lib/lwp.
Dmitri did explain to me offline, but I am still not clear. e.g.:
It
seems like /usr/lib/lwp/libthread.so uses a different threadingmodel
than the one /usr/lib.
In any case, how do you monitor that using libthread.so in/usr/lib/lwp
did
have an effect? ps?
Mike Reiche wrote:
Follow the links in this link.
h
tp://newsgroups.bea.com/cgi-bin/dnewsweb?cmd=article&group=weblogic.develo
per.interest.performance&item=3134&utag=
Jesus M. Salvo Jr. <[email protected]> wrote:
Okay, I have seen earlier posts that suggests to put
/usr/lib/lwp in
front
of your LD_LIBRARY_PATH for Solaris 8 and for JDK 1.3.1. A lothave
said
that increased the performance by 10 to 20%.
From what I can see, this will effectively use libthread.so in
/usr/lib/lwp
instead of the the shared library with the same name in/usr/lib.
What is the difference between those two shared libraries? My
understanding
that Solaris always uses lwp ( light-weight processes ..many-to-many
) by
default anyway, so I am curious as to what the directory name"lwp"
mean.
Will BEA support this if you change the LD_LIBRARY_PATH?
Thanks,
John
[att1.html]