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Subject: Re: Apache 2.4, Worker MPM, SVN 1.7.20, MOD_DAV_SVN and Post-Commit
 Hooks
To: Philip Martin <philip.martin@wandisco.com>
References: <56BC2F46.2040404@steffen-moser.de> <877fib5y1f.fsf@wandisco.com>
From: Steffen Moser <lists@steffen-moser.de>
Cc: users@subversion.apache.org
Message-ID: <56BD113B.9000209@steffen-moser.de>
Date: Thu, 11 Feb 2016 23:54:51 +0100
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Hi Philip,

thank you very much for your fast reply!

On 02/11/2016 11:41 AM, Philip Martin wrote:
> Steffen Moser <lists@steffen-moser.de> writes:
> 
>> So my questions to you are:
>>
>>  1) Are there any known multi-threading problems with the combination
>> Apache 2.4 MPM Worker, SVN 1.7.x, MOD_DAV_SVN and hooks?
> 
> I would expect it to work although we do not get many reports of
> Subversion on Solaris so it is possible there is a bug.  Subversion 1.7
> is old.

You are absolutely right, it is quite old, but I haven't had the time
yet for integrating 1.8.x or 1.9.x into Solaris' build system.

Fortunately, there are only two quite small patches from Oracle which
the build system applies when compiling 1.7.x. Most probably, I just
have to look what is actually needed of these patches and in how far I
have to modify them to get 1.8.x or 1.9.x built. Most of the patched
items are related to the directory position of libraries in the system.

A simple exchange of 1.7.20 by 1.9.3 in Oracle's build tools failed as
it it doesn't apply the patches (but I tried it only quite quickly
today) correctly.

> We did have a Solaris buidbot running Solaris 10 and it ran the
> regression tests over svn:// with svnserve in threaded mode.  I believe
> I also had success with the tests over http:// with Apache worker but I
> can't remember for sure.
> 
>>  2) Is there any alternative to access an SVN repository via Apache
>> besides using the MOD_DAV_SVN module in Apache? For example, can I
>> possibly use "Fast CGI" to link SVN to Apache? (This is, for example,
>> a solution to run the non-thread-safe PHP in a multi-threaded Worker
>> MPM).
> 
> No.
> 
>>  3) What is the recommended way to solve the problem? Do I really have
>> to go without a multi-threaded web server?
> 
> Is your repository BDB?  If so you could try migrating to FSFS.  If you
> are using BDB which version is the library?

According to "svn/db/fs-type" it is FSFS, so non-thread-safe outdated
BDB libraries shouldn't be the cause of the problem.

> You could try running svnserve in threaded mode with the svn:// protocol
> to see if the problem is limited to Apache.

I'll try this. Thank you for the hint. I didn't know that the SVN daemon
is also capable of doing multi-threading.

> You could try building more recent APR/Apache/Subversion.

Good idea. I think I am proceeding this way:

 1) I try the SVN daemon instead of Apache/MOD_DAV_SVN.

 2) I am going to upgrade Apache from 2.4.12 to 2.4.16 as there are
binaries for Solaris 11.3 in an early access distribution:

https://blogs.oracle.com/solarisfoss/entr
/foss_evaluation_packages_for_solaris

 3) Subversion 1.7.x is indeed quite outdated. Therefore, I am going to
build Subversion 1.8.15 or, if possible, even 1.9.3.

 4) The version of APR which comes with Solaris 11.3 is 1.5.1, so it
should be not too old. Therefore I would try this as a last step.

Kind regards,
Steffen


-- 
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Dipl.-Inf. Steffen Moser
School of Advanced Professional Studies            Room: O27/317
Ulm University                                     Tel: +49.731.50-24179
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89081 Ulm, Germany                               http://saps.uni-ulm.de/