- with IOstreamOption there are no cases where we need to construct
top-level streams (eg, IFstream, OFstream) with additional information
about the internal IOstream 'version' (eg, version: 2.0).
Makes it more convenient to open files with a specified
format/compression combination - no clutter of specifying the
version
STYLE: qualify format/version/compression with IOstreamOption not IOstream
STYLE: reduce number of lookups when scanning {fa,fv}Solution
STYLE: call IOobject::writeEndDivider as static
- wrap command-line retrieval of fileName with an implicit validate.
Instead of this:
fileName input(args[1]);
fileName other(args["someopt"]);
Now use this:
auto input = args.get<fileName>(1);
auto other = args.get<fileName>("someopt");
which adds a fileName::validate on the inputs
Because of how it is implemented, it will automatically also apply
to argList getOrDefault<fileName>, readIfPresent<fileName> etc.
- adjust fileName::validate and clean to handle backslash conversion.
This makes it easier to ensure that path names arising from MS-Windows
are consistently handled internally.
- dictionarySearch: now check for initial '/' directly instead of
relying on fileName isAbsolute(), which now does more things
BREAKING: remove fileName::clean() const method
- relying on const/non-const to control the behaviour (inplace change
or return a copy) is too fragile and the const version was
almost never used.
Replace:
fileName sanitized = constPath.clean();
With:
fileName sanitized(constPath);
sanitized.clean());
STYLE: test empty() instead of comparing with fileName::null
Original commit message:
------------------------
Parallel IO: New collated file format
When an OpenFOAM simulation runs in parallel, the data for decomposed fields and
mesh(es) has historically been stored in multiple files within separate
directories for each processor. Processor directories are named 'processorN',
where N is the processor number.
This commit introduces an alternative "collated" file format where the data for
each decomposed field (and mesh) is collated into a single file, which is
written and read on the master processor. The files are stored in a single
directory named 'processors'.
The new format produces significantly fewer files - one per field, instead of N
per field. For large parallel cases, this avoids the restriction on the number
of open files imposed by the operating system limits.
The file writing can be threaded allowing the simulation to continue running
while the data is being written to file. NFS (Network File System) is not
needed when using the the collated format and additionally, there is an option
to run without NFS with the original uncollated approach, known as
"masterUncollated".
The controls for the file handling are in the OptimisationSwitches of
etc/controlDict:
OptimisationSwitches
{
...
//- Parallel IO file handler
// uncollated (default), collated or masterUncollated
fileHandler uncollated;
//- collated: thread buffer size for queued file writes.
// If set to 0 or not sufficient for the file size threading is not used.
// Default: 2e9
maxThreadFileBufferSize 2e9;
//- masterUncollated: non-blocking buffer size.
// If the file exceeds this buffer size scheduled transfer is used.
// Default: 2e9
maxMasterFileBufferSize 2e9;
}
When using the collated file handling, memory is allocated for the data in the
thread. maxThreadFileBufferSize sets the maximum size of memory in bytes that
is allocated. If the data exceeds this size, the write does not use threading.
When using the masterUncollated file handling, non-blocking MPI communication
requires a sufficiently large memory buffer on the master node.
maxMasterFileBufferSize sets the maximum size in bytes of the buffer. If the
data exceeds this size, the system uses scheduled communication.
The installation defaults for the fileHandler choice, maxThreadFileBufferSize
and maxMasterFileBufferSize (set in etc/controlDict) can be over-ridden within
the case controlDict file, like other parameters. Additionally the fileHandler
can be set by:
- the "-fileHandler" command line argument;
- a FOAM_FILEHANDLER environment variable.
A foamFormatConvert utility allows users to convert files between the collated
and uncollated formats, e.g.
mpirun -np 2 foamFormatConvert -parallel -fileHandler uncollated
An example case demonstrating the file handling methods is provided in:
$FOAM_TUTORIALS/IO/fileHandling
The work was undertaken by Mattijs Janssens, in collaboration with Henry Weller.
