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Re: Performance and scalability of Jigsaw

From: Anselm Baird_Smith <abaird@www43.inria.fr>
Date: Thu, 27 Feb 1997 23:10:20 +0100 (MET)
Message-Id: <199702272210.XAA22894@www43.inria.fr>
To: francois.deza@sema.fr
Cc: www-jigsaw@w3.org
Francois Deza writes:
 > Anselm,
 > Good to have you reply in such interesting details.
 > I have two other questions.
 > We have noticed that the busyCount instance variable
 > , although defined, is never used in jigsaw?
 > Is it normal?

I think its a historical artifact, the variable should have been

 > Do you know if JDK 1.1 implements the keepalive http 1.1 feature?
 > We have observed that they are more requests sent by the Stresser than
 > they are
 > sockets accepted by Jigsaw. It is as if the keepalive feature was
 > present.

I haven't checked it, but knowing the plans, I wouldn't be surprise if
it did implement persistent connections (even though not strictly 1.1
persistent connections).

 > To finish, I can confirm there is something strange happening to Jigsaw
 > upon heavy load.
 > Certain requests get blocked forever.
 > We observed that in the Stresser utility some threads block forever
 > on the read. When we kill Jigsaw, sockets get closed and exceptions get
 > generated
 > by the blocking read in the Stresser. This unblocks the Stresser which
 > then returns.
 > Same for httpd.

Strange, I would be glad to get a thread dump right before you kill
the server (send SIGQUIT under UNIX to the server). Just mail me the
traces, this will be of great interest (at least to me ;-)

 > This is very strange especially if you know that Jigsaw occupies 0% of
 > the CPU
 > at that time. It is as if something was blocking the requests in Jigsaw.
 > We are tracking it down. I can at least say it is not in the write
 > happening on Jigsaw.
 > When threads enter the method in which the write takes place, they
 > always finish
 > the job. This is something before. 

I am afraid of yet another Java bug, but let's see the thread dump

Received on Thursday, 27 February 1997 17:10:25 UTC

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