Le vendredi 18 avril 2008, Sridhar Vinay a écrit :
> Hi Renaud,
>
> The float_bessel testcase, as a matter of fact, all float_* testcases seem
> to fail when multiple instances are run concurrently. The failures occur
> because file sizes don't match or because the number of bytes read don't
> match the file size. This can be attributed to the parallel instance
> reading a file before the write to it (by another instance) has completed.
> In such situations, either the file size has not been updated in the inode
> header or the file size has been updated but the file's write operation has
> not been updated completely. To fix this concurrency problem, my suggestion
> is to check for an existing instance and wait for it to finish before
> beginning the current instance.

Doing this, you remove concurrency by serializing the execution of different
instances.

> Any other concurrency resolution technique 
> may complicate matters. A message to the console indicating such a decision
> might be added. What would you suggest?

A had a quick look at the code. IMO, the problem comes from the competition
between an instance creating the data files and another instance reading
the files. Since all instances are using the same files, one process can
destroy and recreate a file being used by another process !

A simple solution in this case is to execute each instance in a separate
directory to make them working on different files. This is already done in
many LTP tests. The tst_tmpdir function does this.

Regards.

R.

-- 
Renaud Lottiaux

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