Bug #978


Concurrent loading and viewing of plots issues

Added by Gabriel Farrell about 21 years ago. Updated about 19 years ago.

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There are two places in the system that may not be safe if used concurrently.

During loading of mdb plots the file is saved to the filesystem of the machine
hosting the rmi server. If a different user were to try to load a plot before
the previous one is read then it is likely that the system would intermingle the
data from the two plots. This needs to be confirmed.

The simple solution is to lock the plot loading component until it is finished
its work and send the next user a message like "System busy try latter". This is
not ideal.
Mike Lee suggested creating a unique ODBC connection and filename for each
uploaded file and remove them when finished. This is a good idea, not sure how
long this would take to impliment since I need to learn how to do this but it
sounds straightforward ... need to investigate.

The other potential problem is with the viewing/downloading plots. This is a
similar case where a file is writtian to the system and another process presents
it to the user.

I think this could be handled by not writing the file to disk and passing it as
around as an in memory java object. This may already be the implimented and no
problem exists, if not it is a quick fix.

Actions #1

Updated by Gabriel Farrell over 20 years ago

This work has been completed, form the web-interface I am unware of any existing
concurency issues.

The plot loading via the rmi-server has a lock around it that I hope is adequate
in real use cases but it is not robust in a all cases ( 10 minute lock). Ideally
the rmi subsystem goes the way of the dodo but right now it is the primary means
of getting data into the system.

Actions #2

Updated by Michael Lee about 19 years ago

changed from components that are to be deleted to "misc" so that bugs don't get
deleted with component. Sorry for all the email.

Actions #3

Updated by Redmine Admin almost 11 years ago

Original Bugzilla ID was 978


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