Re: GNU Parallel Bug Reports [parallel] parallel-20110205 hangs in "make check" step

[Ole Tange]

On Fri, Feb 11, 2011 at 1:19 AM, Ido Tal <address@hidden> wrote:

> * A user submits many jobs to a queue.
> * The queuing system distributes the jobs between the different computer
> nodes that make up the supercomputer.
> * Each node has its own CPU, but the file system is shared between the
> nodes.
>
> Now, if the jobs sent were making use of parallel with the sem option, then
> it seems the bug would occur. In this case, I think it would make sense for
> each host to have its own file.

Yes. In this situation we may see the bug.

First of all I would prefer to have this bug fixed instead of making
some workaround. For that I need help in making something that will
create a lock that will work across multiple machines over NFS.

In my opinion 'sem -j1 --id myname myprg' should guarantee that only
one process is running using the filesystem of $HOME. It is to
guarantee that myprg can do something that would f*ck up if multiple
myprgs were running at the same time. If we change the behaviour so we
only guarantee that there will be a single myprg PER MACHINE, then
that would not do what I would expect as a user.

That is why I am reluctant to just implement a PER MACHINE lock.

It would be helpful to me if you can provide a setup and an example
that will fail every time (or at least most times).


/Ole