- can be broadly categorised as 'unthreaded'
or 'collated' (threading requirement depends on buffering)
without other opaque inheritances.
CONFIG: add hostUncollated to bash completion prompt
- use local function for the decision making, whether worldComm or a
dedicated communicator is needed (and which sibling ranks are
involved)
Co-authored-by: mattijs <mattijs>
- accept plain lists (space or comma separated) as well as the
traditional OpenFOAM lists. This simplifies argument handling
with job scripts.
For example,
simpleFoam -ioRanks 0,4,8 ...
vs
simpleFoam -ioRanks '(0 4 8)' ...
It is also possible to select the IO ranks on a per-host basis:
simpleFoam -ioRanks host ...
- expose rank/subrank handling as static fileOperation methods
- previously checked on destruction, but it is robuster to check for a
locally defined communicator during construction
- add InfoProxy output for fileOperation
ENH: add fileOperation::storeComm()
- transfers management of the communicator from external to internal.
Use with caution
- make fileHandler deletion mechanism more
transparent by providing a nullptr signature. A nullptr parameter
is already being used in the argList destructor for shutdown, but that
relied on an implicit conversion to autoPtr to trigger things.
- improved handling of file handler replacement.
Previously had a very basic check on old vs new handlers using their
type() values (string comparison!!), which would unfortunately
prevent proper swapping of the contents.
Check the actual pointers instead.
As part of the change, treat any empty autoPtr as no-op instead of as
deletion (which is handled explicitly as nullptr instead).
In addition to making the internal logic simpler, it means that the
current file handler always changes to a valid state without
inadvertently removing everything and falling back to creating a new
default handler (again).
This handling of no-ops also simplifies call code. For example,
<code>
autoPtr<fileHandler> oldHandler;
autoPtr<fileHandler> writeHandler;
word handlerName;
if (arg.readIfPresent("writeHandler", handlerName))
{
writeHandler = fileOperation::New(handlerName);
}
oldHandler = fileHandler(std::move(writeHandler));
... do something
writeHandler = fileHandler(std::move(oldHandler));
</code>
If the "writeHandler" is not specified, each call is a no-op.
If it is specified, the handlers are swapped out each time.
- the management of the fileHandler communicators is now encapsulated
privately (managedComm_) with the final layer being responsible for
cleaning up after itself. This makes delegation/inheritance clearer
and avoids the risk of freeing an MPI communicator twice.
STYLE: uniformFile static check relocated to fileOperation layer
- recover the target of symbolic links.
This is needed when re-creating a file tree on another rank.
ENH: handle checkGzip, followLink flags in fileHander filePath()
- previously just relied on the backend defaults, now pass through
- separate init(...) for common constructor init steps
- improves interface and data consistency.
Older signatures are still active (via the Foam_IOstream_extras
define).
- refine internals for IOstreamOption streamFormat, versionNumber
ENH: improve data alignment for IOstream and IOobject
- fit sizeof label/scalar into unsigned char
STYLE: remove dead code
Improvements to existing functionality
--------------------------------------
- MPI is initialised without thread support if it is not needed e.g. uncollated
- Use native c++11 threading; avoids problem with static destruction order.
- etc/cellModels now only read if needed.
- etc/controlDict can now be read from the environment variable FOAM_CONTROLDICT
- Uniform files (e.g. '0/uniform/time') are now read only once on the master only
(with the masterUncollated or collated file handlers)
- collated format writes to 'processorsNNN' instead of 'processors'. The file
format is unchanged.
- Thread buffer and file buffer size are no longer limited to 2Gb.
The global controlDict file contains parameters for file handling. Under some
circumstances, e.g. running in parallel on a system without NFS, the user may
need to set some parameters, e.g. fileHandler, before the global controlDict
file is read from file. To support this, OpenFOAM now allows the global
controlDict to be read as a string set to the FOAM_CONTROLDICT environment
variable.
The FOAM_CONTROLDICT environment variable can be set to the content the global
controlDict file, e.g. from a sh/bash shell:
export FOAM_CONTROLDICT=$(foamDictionary $FOAM_ETC/controlDict)
FOAM_CONTROLDICT can then be passed to mpirun using the -x option, e.g.:
mpirun -np 2 -x FOAM_CONTROLDICT simpleFoam -parallel
Note that while this avoids the need for NFS to read the OpenFOAM configuration
the executable still needs to load shared libraries which must either be copied
locally or available via NFS or equivalent.
New: Multiple IO ranks
----------------------
The masterUncollated and collated fileHandlers can now use multiple ranks for
writing e.g.:
mpirun -np 6 simpleFoam -parallel -ioRanks '(0 3)'
In this example ranks 0 ('processor0') and 3 ('processor3') now handle all the
I/O. Rank 0 handles 0,1,2 and rank 3 handles 3,4,5. The set of IO ranks should always
include 0 as first element and be sorted in increasing order.
The collated fileHandler uses the directory naming processorsNNN_XXX-YYY where
NNN is the total number of processors and XXX and YYY are first and last
processor in the rank, e.g. in above example the directories would be
processors6_0-2
processors6_3-5
and each of the collated files in these contains data of the local ranks
only. The same naming also applies when e.g. running decomposePar:
decomposePar -fileHandler collated -ioRanks '(0 3)'
New: Distributed data
---------------------
The individual root directories can be placed on different hosts with different
paths if necessary. In the current framework it is necessary to specify the
root per slave process but this has been simplified with the option of specifying
the root per host with the -hostRoots command line option:
mpirun -np 6 simpleFoam -parallel -ioRanks '(0 3)' \
-hostRoots '("machineA" "/tmp/" "machineB" "/tmp")'
The hostRoots option is followed by a list of machine name + root directory, the
machine name can contain regular expressions.
New: hostCollated
-----------------
The new hostCollated fileHandler automatically sets the 'ioRanks' according to
the host name with the lowest rank e.g. to run simpleFoam on 6 processors with
ranks 0-2 on machineA and ranks 3-5 on machineB with the machines specified in
the hostfile:
mpirun -np 6 --hostfile hostfile simpleFoam -parallel -fileHandler hostCollated
This is equivalent to
mpirun -np 6 --hostfile hostfile simpleFoam -parallel -fileHandler collated -ioRanks '(0 3)'
This example will write directories:
processors6_0-2/
processors6_3-5/
A typical example would use distributed data e.g. no two nodes, machineA and
machineB, each with three processes:
decomposePar -fileHandler collated -case cavity
# Copy case (constant/*, system/*, processors6/) to master:
rsync -a cavity machineA:/tmp/
# Create root on slave:
ssh machineB mkdir -p /tmp/cavity
# Run
mpirun --hostfile hostfile icoFoam \
-case /tmp/cavity -parallel -fileHandler hostCollated \
-hostRoots '("machineA" "/tmp" "machineB" "/tmp")'
Contributed by Mattijs Janssens
