Environment variables

Some pieces of core Celeritas code interrogate the environment for variables to change system- or output-level behavior. These variables are checked once per execution, and checking them inserts the key and user-defined value (or empty) into a diagnostic database saved to Celeritas’ JSON output, so the user can tell what variables are in use or may be useful.

Environment variables used by Celeritas.

Variable	Component	Brief description
CELER_COLOR	corecel	Enable/disable ANSI color logging
CELER_DEBUG_DEVICE	corecel	Increase device error checking and output
CELER_DISABLE_DEVICE	corecel	Disable CUDA/HIP support
CELER_DISABLE_PARALLEL	corecel	Disable MPI support
CELER_DISABLE_ROOT	corecel	Disable ROOT I/O calls
CELER_DEVICE_ASYNC	corecel	Flag for asynchronous memory allocation
CELER_ENABLE_PROFILING	corecel	Set up NVTX/ROCTX profiling ranges [3]
CELER_LOG	corecel	Set the “global” logger verbosity
CELER_LOG_LOCAL	corecel	Set the “local” logger verbosity
CELER_MEMPOOL… [2]	corecel	Change cudaMemPoolAttrReleaseThreshold
CELER_PERFETT… [1]	corecel	Set the in-process tracing buffer size
CELER_PROFILE_DEVICE	corecel	Record extra kernel launch information
CUDA_HEAP_SIZE	geocel	Change cudaLimitMallocHeapSize (VG)
CUDA_STACK_SIZE	geocel	Change cudaLimitStackSize for VecGeom
G4VG_COMPARE_VOLUMES	geocel	Check G4VG volume capacity when converting
HEPMC3_VERBOSE	celeritas	HepMC3 debug verbosity
VECGEOM_VERBOSE	celeritas	VecGeom CUDA verbosity
CELER_DISABLE	accel	Disable Celeritas offloading entirely
CELER_KILL_OFFLOAD	accel	Kill Celeritas-supported tracks in Geant4
CELER_NONFATAL_FLUSH	accel	Instead of crashing, kill tracks [4]
CELER_STRIP_SOURCEDIR	accel	Strip directories from exception output

[1]

CELER_PERFETTO_BUFFER_SIZE_MB

[2]

CELER_MEMPOOL_RELEASE_THRESHOLD

[3]

See Profiling

[4]

Normally, exceeding the “maximum steps” or interrupting the stepping loop will call G4Exception, which normally kills the code. (In external frameworks this usually causes a stack trace and core dump.) Instead of doing that, kill all the active tracks and print their state. If more tracks are buffered, those will continue to transport.

Some of the Celeritas-defined environment variables have prefixes from other libraries because they directly control the behavior of that library and nothing else. The CELER_DEVICE_ASYNC may be needed when running HIP 5.7 or later due to the “beta” nature of hipMallocAsync: it defaults to “true” except for HIP less than 5.2 (where it is not implemented) or greater than 5.6.

Environment variables from external libraries can also be referenced by Celeritas or its apps:

Environment variables used by relevant external libraries.

Variable	Library	Brief description
CUDA_VISIBLE_DEVICES	CUDA	Set the active CUDA device
HIP_VISIBLE_DEVICES	HIP	Set the active HIP device
G4LEDATA	Geant4	Path to low-energy EM data
G4FORCE_RUN_MANAGER_TYPE	Geant4	Use MT or Serial thread layout
G4FORCENUMBEROFTHREADS	Geant4	Set CPU worker thread count
OMP_NUM_THREADS	OpenMP	Number of threads per process

Note

For frameworks integrating Celeritas, these options are configurable via the Celeritas API. Before Celeritas is set up for the first time, on a single thread access the celeritas::environment() struct (see System), and call insert for the desired key/value pairs.

Logging

The Celeritas library writes informational messages to stderr. The given levels can be used with the CELER_LOG and CELER_LOG_LOCAL environment variables to suppress or increase the output. The default is to print diagnostic messages and higher.

Logging levels in increasing severity.

Level	Description
debug	Low-level debugging messages
diagnostic	Diagnostics about current program execution
status	Program execution status (what stage is beginning)
info	Important informational messages
warning	Warnings about unusual events
error	Something went wrong, but execution can continue
critical	Something went terribly wrong, program termination imminent