Setting up Your Environment for Chapel

To get started with Chapel, there are three environment settings that are strongly recommended for effective use of the release, and a number of other optional settings that are useful for cross-compiling or overriding the default settings. To check the values of the Chapel environment variables that are set or can be inferred, run the command:

$CHPL_HOME/util/printchplenv --all

The setchplenv.* source scripts in the $CHPL_HOME/util/quickstart/ and $CHPL_HOME/util/ directories contain commands that set the following variables for various shells and host platforms when they are sourced from the $CHPL_HOME directory. Frequent Chapel users may want to add such settings to their shell’s dotfile(s); but for getting started the setchplenv.* scripts can be convenient.

Optional Settings

CHPL_HOST_PLATFORM

You can set the CHPL_HOST_PLATFORM environment variable to represent the platform on which you’re working. For standard UNIX workstations, the default is sufficient, and is equivalent to

export CHPL_HOST_PLATFORM=`$CHPL_HOME/util/chplenv/chpl_platform.py`

For other platforms that appear very similar to a UNIX workstation from the shell prompt (e.g., a Cray CS™), the value may need to be set explicitly. The strings for our currently-supported host platforms are as follows:

Value

Description

cygwin32

x86 Cygwin (Windows) platforms

cygwin64

x86_64 Cygwin (Windows) platforms

darwin

Macintosh OS X platforms

linux32

32-bit Linux platforms

linux64

64-bit Linux platforms

netbsd32

32-bit NetBSD platforms

netbsd64

64-bit NetBSD platforms

pwr6

IBM Power6 SMP cluster

sunos

SunOS platforms

cray-cs

Cray CS™

cray-xc

Cray XC™

hpe-cray-ex

HPE Cray EX

hpe-apollo

HPE Apollo

Platform-specific documentation is available for most of these platforms in Platform-Specific Notes.

The Chapel Makefiles and sources are designed to work for any UNIX-compatible environment that supports a GNU-compatible make utility. The list above represents the set of platforms that we have access to and can test easily. We are interested in making our code framework portable to other platforms—if you are using Chapel on a platform other than the ones listed above, please contact us for help with the effort.

CHPL_TARGET_PLATFORM

If you are cross-compiling for a platform other than your $CHPL_HOST_PLATFORM, set the CHPL_TARGET_PLATFORM environment variable to describe that platform. See CHPL_HOST_PLATFORM above for legal values (though whether or not a given setting will support cross-compilation depends on your specific environment).

Note

If CHPL_TARGET_PLATFORM is not set, the target platform defaults to the same value as $CHPL_HOST_PLATFORM.

CHPL_HOST_ARCH

Optionally, set the CHPL_HOST_ARCH environment variable to indicate the architecture type of the current machine. Normally, the default value is sufficient.

Value

Description

x86_64

64-bit AMD and Intel processors

aarch64

64-bit ARM processors

If unset, the default will be computed. The command uname -m should produce the same value as the default.

CHPL_TARGET_ARCH

Optionally, set the CHPL_TARGET_ARCH environment variable to indicate the architecture type of the target machine. See the table above for CHPL_HOST_ARCH for values this might be set to.

If unset, CHPL_TARGET_ARCH will be inferred. If CHPL_TARGET_CPU is native, unknown, or none then CHPL_TARGET_ARCH will be set to CHPL_HOST_ARCH. Otherwise, CHPL_TARGET_ARCH will be set based on the architecture type specified in CHPL_TARGET_CPU.

CHPL_*_COMPILER

Optionally, you can set CHPL_HOST_COMPILER and/or CHPL_TARGET_COMPILER to indicate the compiler suite to use in building the sources. CHPL_HOST_COMPILER is the compiler used to build the Chapel compiler itself so that it will run on CHPL_HOST_PLATFORM. CHPL_TARGET_COMPILER is the compiler used to build the runtime libraries and generated code for CHPL_TARGET_PLATFORM. Currently supported values are as follows:

Value

Description

allinea

The Allinea ARM compiler suite – clang and clang++

clang

The Clang compiler suite – clang and clang++

cray-prgenv-allinea

The Cray PrgEnv compiler using the Allinea backend

cray-prgenv-cray

The Cray PrgEnv compiler using the Cray CCE backend

cray-prgenv-gnu

The Cray PrgEnv compiler using the GNU backend

cray-prgenv-intel

The Cray PrgEnv compiler using the Intel backend

cray-prgenv-pgi

The Cray PrgEnv compiler using the PGI backend

gnu

The GNU compiler suite – gcc and g++

ibm

The IBM compiler suite – xlc and xlC

intel

The Intel compiler suite – icc and icpc

llvm

LLVM code generation

pgi

The PGI compiler suite – pgcc and pgc++

The default for CHPL_HOST_COMPILER depends on the value of the corresponding CHPL_HOST_PLATFORM environment variable:

Host Platform

Compiler

hpe-cray-ex

cray-xc

gnu

darwin

freebsd

clang if available, otherwise gnu

pwr6

ibm

other

gnu

The default for CHPL_TARGET_COMPILER is:

  • llvm if the compiler is configured with LLVM support (see CHPL_LLVM)

  • cray-prgenv-$PE_ENV on cray-xc and hpe-cray-ex platforms (where PE_ENV is set by PrgEnv-* modules)

  • CHPL_HOST_COMPILER if the host and target platforms are the same

  • gnu otherwise.

In cases where the LLVM code generation strategy is the default, setting CHPL_TARGET_COMPILER to something other than llvm will request that the C backend be used with that compiler. For example, to select the C backend with the PrgEnv-gnu compiler, set CHPL_TARGET_COMPILER=cray-prgenv-gnu.

It is sometimes important to be able to provide a particular command to run for C or C++ compilation. The following variables are available to help with that:

Variable

Description

CC

indicates the C compiler to use (but see note below)

CXX

indicates the CXX compiler to use (but see note below)

CHPL_HOST_CC

indicates the C compiler for building chpl itself

CHPL_HOST_CXX

indicates the C++ compiler for building chpl itself

CHPL_TARGET_CC

indicates the C compiler used by chpl

CHPL_TARGET_CXX

indicates the C++ compiler used by chpl

Note

If the CC and CXX variables are set, the other variables in the above table can be inferred. When these variables are used, the following variables can be inferred from them:

  • CHPL_HOST_COMPILER, CHPL_HOST_CC, CHPL_HOST_CXX

  • CHPL_TARGET_COMPILER, CHPL_TARGET_CC, CHPL_TARGET_CXX

However:

  • Setting any of these inferred variables will disable the inference for all of them

  • The *TARGET* variables above are not inferred from CC / CXX when CHPL_TARGET_COMPILER=llvm or when working with a PrgEnv compiler.

CHPL_TARGET_CPU

Optionally, set the CHPL_TARGET_CPU environment variable to indicate that the target executable should be specialized to the given architecture when using --specialize (and --fast). Valid options are:

Value

Description

native

The C compiler will attempt to detect the architecture on the machine that is compiling the target executable. This is a good choice if you will be running on the same machine that you are compiling on. If you are not, see the options below.

unknown

No specialization will be performed

none

No specialization will be performed (will not warn)

Architecture-specific values

intel

amd

arm

core2

k8

aarch64

nehalem

k8sse3

thunderx

westmere

barcelona

thunderx2t99

sandybridge

bdver1

ivybridge

bdver2

haswell

bdver3

broadwell

bdver4

skylake

knl

These values are defined to be the same as in GCC 7:

If you do not want CHPL_TARGET_CPU to have any effect, you can set it to either unknown or none. Both will disable specialization, but the latter will not warn if --specialize is used.

Setting CHPL_TARGET_CPU to an incorrect value for your processor may result in an invalid binary that will not run on the intended machine. Special care should be taken to select the lowest common denominator when running on machines with heterogeneous processor architectures.

The default value for this setting will vary based on settings in your environment, in order of application these rules are:

  • If CHPL_TARGET_COMPILER is cray-prgenv-* you do not need to set anything in CHPL_TARGET_CPU. One of the craype-* modules (e.g. craype-sandybridge) should be loaded to provide equivalent functionality. Once the proper module is loaded, CRAY_CPU_TARGET will have the architecture being used in it.

  • If CHPL_TARGET_COMPILER is cray, pgi, or ibm, CHPL_TARGET_CPU will be set to none and no specialization will occur.

  • If CHPL_COMM is set, no attempt to set a useful value will be made and CHPL_TARGET_CPU will be unknown.

  • If CHPL_TARGET_PLATFORM is darwin, linux*, or cygwin* CHPL_TARGET_CPU will be native, passing the responsibility off to the backend C compiler to detect the specifics of the hardware.

CHPL_MAKE

Optionally, set the CHPL_MAKE environment variable to indicate the GNU-compatible make utility that you want the compiler back-end to invoke when compiling the generated C code. If not set, this will default to a value based on $CHPL_HOST_PLATFORM:

platform

make utility

cygwin*, darwin

make

linux32, linux64

gmake if available, otherwise make

other

gmake

CHPL_MODULE_PATH

Optionally, set the CHPL_MODULE_PATH environment variable to provide a list of directories to be added to the Module Search Paths. The value of this environment variable should be a colon-separated list of directory paths.

The module search path is used to satisfy ‘use’ statements in the Chapel program. The complete search path can be displayed using the compiler option --print-search-dirs. It will also include the compiler’s standard module search paths, those introduced by the -M flag on the command line and directories containing the .chpl files named explicitly on the compiler command line.

CHPL_LOCALE_MODEL

Optionally, set the CHPL_LOCALE_MODEL environment variable to indicate the locale model you want to use. Current options are:

Value

Description

flat

top-level locales are not further subdivided

numa

top-level locales are further subdivided into sublocales, each one a NUMA domain

If unset, CHPL_LOCALE_MODEL defaults to flat.

See Locale Models for more information about locale models.

CHPL_TASKS

Optionally, set the CHPL_TASKS environment variable to indicate what tasking layer you want to use to implement intra-locale parallelism (see Chapel Tasks for more information on this option). Current options are:

Value

Description

qthreads

use Sandia’s Qthreads package

fifo

use POSIX threads

If CHPL_TASKS is not set it defaults to qthreads in all cases except for a few specific configurations in which it defaults to fifo:

  • target platform is cygwin*

  • target platform is netbsd*

Note

Note that the Chapel util/quickstart/setchplenv.* source scripts set CHPL_TASKS to fifo to reduce build-time and third-party dependences, while the util/setchplenv.* versions leave it unset, resulting in the behavior described just above.

See Chapel Tasks for more information about executing using the various CHPL_TASKS options.

CHPL_COMM

Optionally, set the CHPL_COMM environment variable to indicate what communication layer you want to use to implement inter-locale communication. Current options are:

Value

Description

none

only supports single-locale execution

gasnet

use the GASNet-based communication layer

ofi

use the libfabric-based communication layer

ugni

Cray-specific native communication layer

If unset, CHPL_COMM defaults to none in most cases. On Cray XC systems it defaults to ugni. On Cray CS systems it defaults to gasnet. See Multilocale Chapel Execution for more information on executing Chapel programs using multiple locales. See Using Chapel with libfabric for more information about the ofi communication layer. See Using Chapel on Cray Systems for more information about Cray-specific runtime layers.

CHPL_MEM

Optionally, the CHPL_MEM environment variable can be used to select a memory management layer. Current options are:

Value

Description

cstdlib

use the standard C malloc/free commands

jemalloc

use Jason Evan’s memory allocator

If unset, CHPL_MEM defaults to jemalloc for most configurations. If the target platform is cygwin* it defaults to cstdlib

CHPL_TARGET_MEM will be replacing CHPL_MEM in the future. CHPL_TARGET_MEM takes precedence over CHPL_MEM.

Note

Certain CHPL_COMM settings (e.g. ugni, gasnet segment fast/large, ofi with the gni provider) register the heap to improve communication performance. Registering the heap requires special allocator support that not all allocators provide. Currently only jemalloc is capable of supporting configurations that require a registered heap.

CHPL_HOST_MEM

Optionally, the CHPL_HOST_MEM environment variable can be used to select a memory management layer for the chpl compiler.

Value

Description

cstdlib

use the standard C malloc/free commands

jemalloc

use Jason Evan’s memory allocator

If unset, CHPL_HOST_MEM defaults to cstdlib.

CHPL_HOST_JEMALLOC

Optionally, the CHPL_HOST_JEMALLOC environment variable can select between no jemalloc, or using the jemalloc distributed with Chapel in third-party. This setting is intended to elaborate upon CHPL_HOST_MEM=jemalloc.

Value

Description

none

do not build or use jemalloc

bundled

use the jemalloc distribution bundled with Chapel in third-party

system

use jemalloc found on system. requires jemalloc-config in PATH

Currently, the only supported combinations of host target are:

Host

Source

darwin

system

linux

bundled

If unset, CHPL_HOST_JEMALLOC defaults to one of the above support combinations, or none if CHPL_HOST_MEM is cstdlib.

CHPL_LAUNCHER

Optionally, the CHPL_LAUNCHER environment variable can be used to select a launcher to get your program up and running. See Chapel Launchers for more information on this variable’s default and possible settings.

CHPL_ATOMICS

Optionally, the CHPL_ATOMICS environment variable can be used to select an implementation for atomic operations in the runtime. Current options are:

Value

Description

cstdlib

implement atomics with C standard atomics (from C11)

intrinsics

implement atomics with target compiler intrinsics

locks

implement atomics with mutexes

If CHPL_ATOMICS is not set, it defaults to cstdlib when the target compiler is gnu, clang, allinea, llvm, or cray. It defaults to intrinsics when the target compiler is intel. It defaults to locks when the target compiler is pgi.

See the Chapel Language Specification for more information about atomic operations in Chapel or Runtime Support for Atomics for more information about the runtime implementation.

CHPL_TIMERS

Optionally, the CHPL_TIMERS environment variable can be used to select an implementation for Chapel’s timers. Current options are:

generic

use a gettimeofday()-based implementation

If unset, CHPL_TIMERS defaults to generic

CHPL_GMP

Optionally, the CHPL_GMP environment variable can select between no GMP support, using the GMP distributed with Chapel in third-party, or using a system GMP. Current options are:

Value

Description

system

use a system install of GMP (#include gmp.h, -lgmp)

none

do not build GMP support into the Chapel runtime

bundled

use the GMP distribution bundled with Chapel in third-party

If unset, Chapel will attempt to build GMP using CHPL_TARGET_COMPILER (noting that the bundled version may not be supported by all compilers). Based on the outcome, Chapel will default to:

Value

Description

bundled

if the build was successful

system

if unsuccessful and CHPL_TARGET_PLATFORM is cray-x*

none

otherwise

Note

Note that the Chapel util/quickstart/setchplenv.* source scripts set CHPL_GMP to none while the util/setchplenv.* versions leave it unset, resulting in the behavior described just above.

CHPL_HWLOC

Optionally, the CHPL_HWLOC environment variable can select between no hwloc support or using the hwloc package distributed with Chapel in third-party.

Value

Description

none

do not build hwloc support into the Chapel runtime

bundled

use the hwloc distribution bundled with Chapel in third-party

If unset, CHPL_HWLOC defaults to bundled if CHPL_TASKS is qthreads. In all other cases it defaults to none. In the unlikely event the bundled hwloc distribution does not build successfully, it should still be possible to use qthreads. To do this, manually set CHPL_HWLOC to none and rebuild (and please file a bug with the Chapel team.) Note that building without hwloc will have a negative impact on performance.

CHPL_RE2

Optionally, the CHPL_RE2 environment variable can be used to enable regular expression operations as defined in Regex. Current options are:

Value

Description

bundled

use the re2 distribution in third-party

none

do not support regular expression operations

If unset, Chapel will attempt to build RE2 using CHPL_TARGET_COMPILER (noting that the bundled version may not be supported by all compilers). Based on the outcome, Chapel will default to:

Value

Description

bundled

if the build was successful

none

otherwise

Note

Note that the Chapel util/quickstart/setchplenv.* source scripts set CHPL_RE2 to 'none while the util/setchplenv.* versions leave it unset, resulting in the behavior described just above.

CHPL_AUX_FILESYS

Optionally, the CHPL_AUX_FILESYS environment variable can be used to request runtime support for certain filesystems.

Value

Description

none

only support traditional Linux filesystems

lustre

enable I/O improvements specific to Lustre filesystems

If unset, CHPL_AUX_FILESYS defaults to none.

CHPL_LLVM

The CHPL_LLVM environment variable enables support for the LLVM back-end to the Chapel compiler (see LLVM Support) and support for extern blocks in Chapel code via the Clang compiler (see C Interoperability). Current options are:

Value

Description

bundled

use the llvm/clang distribution in third-party

system

find a compatible LLVM in system libraries; note: the LLVM must be a version supported by Chapel

none

do not support llvm/clang-related features

unset

indicates that no reasonable default has been inferred, requiring the user to intentionally select another option

If unset, CHPL_LLVM defaults to:

  • none on linux32 where Chapel LLVM support is not yet implemented

  • bundled if you’ve already built the bundled llvm in third-party/llvm

  • system if a compatible system-wide installation of LLVM is detected

  • unset otherwise

If CHPL_LLVM is unset you will need to either add a system-wide installation of LLVM or set CHPL_LLVM to bundled or none.

See Chapel Prerequisites for more information about currently supported LLVM versions.

CHPL_LLVM_CONFIG

In some cases, it is useful to be able to select a particular LLVM installation for use with CHPL_LLVM=system. In that event, in addition to setting CHPL_LLVM=system, you can set CHPL_LLVM_CONFIG to the llvm-config command from the LLVM installation you wish to use.

CHPL_LLVM_GCC_PREFIX

Additionally, in some cases, the configured clang will not work correctly without a --gcc-toolchain flag. The Chapel compiler tries to infer this flag but it does not always do so correctly. As a result, it is sometimes necessary to override it. You can set CHPL_LLVM_GCC_PREFIX to none to disable passing the --gcc-toolchain flag; or you can set it to a directory to pass to clang with the --gcc-toolchain flag.

CHPL_UNWIND

Optionally, the CHPL_UNWIND environment variable can be used to select an unwind library for stack tracing. Current options are:

Value

Description

bundled

use the libunwind bundled with Chapel in third-party

system

assume libunwind is already installed on the system

none

don’t use an unwind library, disabling stack tracing

If unset, CHPL_UNWIND defaults to none

CHPL_LIB_PIC

Optionally, the CHPL_LIB_PIC environment variable can be used to build position independent or position dependent code. This is intended for use when Calling Chapel Code from Other Languages, especially when Using Your Library in Python or when building with --dynamic. Current options are:

Value

Description

pic

build position independent code

none

use the system default, which might be position independent or position dependent

If unset, CHPL_LIB_PIC defaults to none

Character Set

Chapel works with the Unicode character set with the UTF-8 encoding. Chapel programs will use the UTF-8 encoding regardless of the LANG and LC_ALL environment variable settings that the C library uses.

Compiler Command Line Option Defaults

Most of the compiler’s command line options support setting a default value for the option via an environment variable. To see a list of the environment variables that support each option, run the compiler with the --help-env flag. For boolean flags and toggles, setting the environment variable to any value selects that flag.

Chapel Configuration Files

The Chapel configuration file is a file named either chplconfig or .chplconfig that can store overrides of the inferred environment variables listed as a result of executing printchplenv.

Syntax

Below are the valid forms of syntax for Chapel configuration files. All other usages will result in a syntax error.

Definitions

Users can define variables with the following format:

CHPL_ENV=value

Above, the default value of CHPL_ENV will be overridden to be value. All white space is stripped away from definitions.

Ignored Lines

Any lines containing nothing or only white space will be ignored. Comments, which are denoted by the # character, similar to bash or python, are also ignored.

Example

Below is an example of a Chapel configuration file with comments:

# ~/.chplconfig

# Default to multi-locale
CHPL_COMM=gasnet

CHPL_TASKS=qthreads # Use Qthreads

# System GMP is available on these machines
CHPL_GMP=system

To confirm the configuration file is written correctly, you can run printchplenv --all --overrides, which will show a list of variables that are currently being overridden. Values followed by a + have been overridden by the Chapel configuration file, whereas values followed by a * have been overridden by an environment variable.

Generating Configuration Files

To generate a configuration file based on the current configuration, use printchplenv or ./configure.

When using printchplenv, run it with the --simple format flag to get a format compatible with Chapel configuration files.

The --overrides filter flag can be used to print only the variables currently overridden by either environment variables or Chapel configuration file.

For example, to save the current overrides into a Chapel configuration file:

printchplenv --all --simple --overrides > ~/.chplconfig

The printchplenv --all --simple flag can be used to print all the variables of the current configuration. For example:

printchplenv --all --simple > ~/.chplconfig

For more information on using printchplenv, see the printchplenv -h output.

Alternatively, the ./configure script will generate a chplconfig file. See Installing Chapel.

Search Paths and File Names

Though you can put your Chapel configuration file anywhere by setting the $CHPL_CONFIG environment variable to its enclosing directory, you can also place it in your $HOME or $CHPL_HOME directory and Chapel will be able to find it.

The search priority for Chapel configuration files is as follows:

  1. $CHPL_CONFIG

  2. $HOME (~/)

  3. $CHPL_HOME

When both a chplconfig and .chplconfig are present, the visible chplconfig will be prioritized.

Only a single chplconfig file will be used. That is, as soon as a valid Chapel configuration file is found, the definitions of that file are used.

Note

The $CHPL_CONFIG variable is the path to the enclosing directory - not the full path including chplconfig itself.

Variable Priority

Variable precedence goes in the following order:

  1. Explicit compiler flags: chpl --env=value

  2. Environment variables: CHPL_ENV=value

  3. Chapel configuration file: ~/.chplconfig

  4. Inferred environment variables: printchplenv