Date: Sat, 06 Mar 1999 15:43:52 +0100 From: sthaug@nethelp.no To: alexlh@funk.org Cc: freebsd-current@freebsd.org Subject: Re: netscape trouebles Message-ID: <6944.920731432@verdi.nethelp.no> In-Reply-To: Your message of "Sat, 06 Mar 1999 14:14:34 %2B0100" References: <36E12A3A.294D4E2E@funk.org>
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> For quite some time now Netscape 4.5 has been very unstable on my
> -current system. I've cvsup'ed and made world many times in the hope the
> problem would go away.
>
> Today I decided to ktrace it, and see where it would stop.
>
> Of course it now refuses to crash. Even on java stuff that would crash
> it _every_ time without the ktrace.
>
> Now I can start my netscape with "ktrace -f /dev/null netscape", and
> it'll probably be happy, although this is less than a satisfactory
> solution.
>
> I figure that the fact that it runs fine with the ktrace might mean
> something significant, although I wouldn't know what. So if anyone has
> an idea, I'd be delighted to hear about it.
I've had an unstable Netscape ever since upgrading to 3.x. There was
quite a bit of discussion about this around a month ago, but no firm
conclusion was reached. For me, it happens with MOZILLA_NO_ASYNC_DNS
turned on (ie. no separate DNS lookup processes) *and* I access a site
where the corresponding name servers take a long time to answer.
I found some more discussion about Netscape hanging in a Linux related
Web page, and the author has also produced a (Linux specific) patch. I
include the README file below. Sorry, no URL, but it's real easy to
find the package (search for Netscape-pipepatch) with ftpsearch.
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
----------------------------------------------------------------------
The Netscape pipe overflow workaround
=====================================
There is a known problem with most versions of Netscape currently
in use, where the Netscape freezes when loading specific pages.
The lockup is complete - there is no window refreshing and
no reaction to the kill -TERM. The only way out is to kill
the process with SIGKILL or from the window manager and
to manually remove the lock file.
The problem is timing-dependent - while most people seeing
it can reproduce it using specific pages, these pages are
different for different people.
The cause of this problem is quite simple. On most (if
not all Unixes) there is a limit on the pipe size and
writing to a pipe will block, if the pipe is full. This
limit is 4096 bytes on the Linux. The Netscape uses a pipe
for some internal synchronisation and fails to take this
into an account. When the pipe overflows, the Netscape
locks up trying to write into the pipe and nobody
reading it.
The presented workaround is a side-effect of narrowing down
this problem (the goal was to prove, if this is a kernel
or application problem). It is NOT intended as a general solution
to the problem (Netscape developers must fix it) and there
is NO GUARANTEE that it doesn't break something else. However,
the hack helped quite a lot of people and so I decided
to publish it.
The idea behind this hack is to insert a layer between Netscape
and the libc, which catches the problematic pipe and fakes I/O
operations that would otherwise cause the lock-up.
Installation
============
First you must know what version of Netscape you are
using - the keywords here are libc5 and glibc (aka libc6).
This is not necessarily the library your distribution
defaults to - it is perfectly possible to use libc5
Netscape on a glibc-based system.
ldd $MOZILLA_HOME/netscape | grep libc.so
will probably give an idea, but there can be broken installations
of ldd giving questionable results (e.g. libc.so.5 => not found
is a valid answer for a libc5 installation).
Next edit the Makefile and check the LIBC and LIBDL
variables. These should be OK for a glibc Netscape,
you will need to change them for a libc5 one (the
instructions for doing this is in the Makefile).
Compile and install the hack (the default destination
is /usr/local/lib):
make
make install
Now the tricky part - you must set the LD_PRELOAD environment
variable to point to your hack somewhere where only Netscape
can see it. Generally you do this in some starting script
for netscape. As the distributions vary here, you are
basically on your own. The patch for Red Hat 5.2
is included (file starting.script.rh52.patch).
End remarks
===========
The workaround is (C) 1999 Stanislav Meduna. The use,
modification and distribution is completely free. There
is ABSOLUTELY NO WARRANTY and i will NOT support the
workaround. There ARE known problems - it is not
known, if they are caused by the hack or only exposed
by using it - I will NOT try to fix them.
Some of the discussion on this hack is included
in the file Discussion.
If you include the workaround in some distribution,
I would like to hear about it.
Stanislav Meduna
stano@eunet.sk
30. 1. 1999
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