[EP-tech] Manage deposits page loads very slow

David R Newman drn at ecs.soton.ac.uk
Mon May 21 10:02:45 BST 2018

Hi Emilian,

I have a repository that has over 1000 deposits under my user's Manage
Deposits and it only takes a few seconds to load.  First, can I check
which MySQL table engine are you using, is it MyISAM or InnoDB?  I know
that both can have problems dealing with complex queries but sometimes
for different reasons. I am not aware of any particularly complex
queries having been introduced to Manage Deposits between the versions
of EPrints you describe.  However, something I have done to mitigate
complex queries with a number of repositories I manage, is add the
following line to perl_lib/EPrints/Database/mysql.pm:

$self->do('SET @@session.optimizer_search_depth = 3;');

This should be on roughly line 242 and is in the connect function after
the line: $self->do("SET NAMES 'utf8'");.  Its purpose is to stop MySQL
spending too much time working out the optimal way of running the query
before actually running it.  I have to admit, I am not overly confident
this will fix your issue but I do not really have enough information to
suggest anything else and this sort of issue is one that is difficult
to debug remotely over email.

Regarding MySQL and Apache using a lot of memory; these, particularly
the latter, will tend to use as much memory as they can, so if you
increase the RAM they will try to make use of it.  This is rarely
memory that cannot be released if needed by another process, so should
not really cause a problem. However, limiting the amount of
threads/processes Apache can run may be useful.  Particularly, in the
event of a DDOS attack, as you are more likely to be able to still SSH
into the server to investigate what is going on.  I use the following
(Apache 2.4) configuration in

<IfModule mpm_prefork_module>
  StartServers                    2
  MinSpareServers                 2
  MaxSpareServers                 5
  ServerLimit                     30
  MaxClients                      30
  MaxRequestsPerChild             100

RewriteEngine on
RewriteCond %{HTTP_USER_AGENT} ^.*internal\ dummy\ connection.*$ [NC]
RewriteRule .* - [F,L]

If you are running Ubuntu 16.04 or above the I"fModule
mpm_prefork_module" will need changing and potentially some of the
parameters inside that block.

Hope this helps

David Newman

On Mon, 2018-05-21 at 11:26 +0300, Emilian Mitocariu wrote:
> Hi,
> I migrated an eprints instance from version 3.3.7 running on a VM
> with ubuntu 10.04, 1GB RAM and 2 virtual CPUs to the latest eprints
> version 3.3.15 on a VM with ubuntu 16.04, 2.5GB RAM and 2 virtual
> CPUs. I followed the page documented on the eprints wiki for the
> migration.
> There were no problems with loading pages on the old version, but on
> the new server when a user visits the "Manage Deposits" page and has
> a lot of deposits, it takes a while to load the page. For a user with
> 885 deposits, it takes at least 30 seconds.
> I compared the mysql configuration on both VMs and it is similar.
> Also, the eprints indexer is running. During the day, apache and
> mysql seems to use more RAM than it did on the old VM.
> Does anyone know what could cause the slow page load or at least give
> me some pointers where to look?
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> tech
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