old "positions" file form
The change to barycentric-based tracking changed the contents of the
cloud "positions" file to a new format comprising the barycentric
co-ordinates and other cell position-based info. This broke
backwards compatibility, providing no option to restart old cases
(v1706 and earlier), and caused difficulties for dependent code, e.g.
for post-processing utilities that could only infer the contents only
after reading.
The barycentric position info is now written to a file called
"coordinates" with provision to restart old cases for which only the
"positions" file is available. Related utilities, e.g. for parallel
running and data conversion have been updated to be able to support both
file types.
To write the "positions" file by default, use set the following option
in the InfoSwitches section of the controlDict:
writeLagrangianPositions 1;
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.
- in specific cases it can be useful to suppress searching the instances.
For example, if one only wishes to check if a "points" is available at
the given time instance, without searching backwards through all
times.
- manifest in some parallel operations.
STYLE: update foamToEnsight, foamToEnsightParts to use C++ initializer_list
- avoid warning message when removing a non-existent directory (ensight output).
- Use ensightCase for case writing.
Rebase ensightPartCells/ensightPartFaces on
ensightCells/ensightFaces routines.
- Greatly reduces code duplication potential source of errors.
- Less looping when detecting lagrangian clouds and their fields.
- Avoid using Time::setTime() and IOobjectList in tight loops.
They both kill performance immensely.
ENH: provide a -noLagrangian option to foamToEnsight and foamToEnsightParts
for even more control.
Old code:
Found 10990 time steps
Search for moving mesh ... no moving mesh detected.
Startup in 329.09 s
Updated:
Found 10990 time steps
Search for moving mesh ... no moving mesh detected.
Startup in 1.6 s
- Cause was checking "polyMesh/points" via an IOobject.
Short-circuit with a check for a polyMesh/ directory first.
Limit the check to the master-node as well to further reduce
load on the file-system.
------------------------------
ENH: improve per-step conversion times for foamToEnsight.
Old code:
Converting 11001 time steps
Time [0] = 0 Wrote in 1.53 s
Time [1] = 1 Wrote in 1.52 s
...
Time [100] = 100 Elapsed time 205.35 s
Updated:
Converting 11001 time steps
Time [0] = 0 Wrote in 1.4 s
Time [1] = 1 Wrote in 0.07 s
...
Time [100] = 100 Elapsed time 42.4 s
- Speedup by hashing test results from the first conversion step
instead of checking each time.
Check data on all nodes to avoid problems with incomplete writes.
------------------------------
BUG: moving mesh detection failed for foamToEnsightParts
- adjusted to agree with updated foamToEnsight
------------------------------
Note:
- foamToEnsightParts (serial) still has about twice the throughput of
foamToEnsight.
- most notably the '%' which is used as a separator in places
caused problems.
EHN: only use valid ensight file/variable names for writers
- fixed: foamToEnsightParts, ensightSurfaceWriter
- pending: foamToEnsight
BUG: no geometry written for foamToEnsightParts with moving mesh (fixes#142)
- an incorrect path was causing the issue
Moved file path handling to regIOobject and made it type specific so
now every object can have its own rules. Examples:
- faceZones are now processor local (and don't search up anymore)
- timeStampMaster is now no longer hardcoded inside IOdictionary
(e.g. uniformDimensionedFields support it as well)
- the distributedTriSurfaceMesh is properly processor-local; no need
for fileModificationChecking manipulation.
- checkMesh has option to write faceSets or (outside of) cellSets as
sampledSurface format. It automatically reconstructs the set on the master
and writes it to the postProcessing folder (as any sampledSurface). E.g.
mpirun -np 6 checkMesh -allTopology -allGeometry -writeSets vtk -parallel
- fixed order writing of symmTensor in Ensight writers
