Add utility for single-node parallel installations

util/parallel_install.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/bash
+
+# This script launches backgrounded instances of the 'spack install' command
+# for an active Spack environment ($SPACK_ENV must be set). The first two
+# arguments are required, specifying the number of instances and number of
+# threads per instance, respectively. Remaining arguments are passed to the
+# 'spack install' command. It is strongly recommended to only run this utility
+# in a concretized environment. The script can be sourced so that the
+# backgrounded jobs are associated with the current shell environment (strongly
+# recommended when running inside a 'screen' or 'tmux' session).
+#
+# NOTE: If you are installing on a shared system (i.e., an HPC platform),
+# especially if not running through a job scheduler with specified resources,
+# be respectful of system resources and usage policies.
+#
+# *Depending on available resources*, for building the entire spack-stack
+# unified environment, 2-4 instances with 4-8 cores each is generally
+# reasonable. Six or more instances is generally overkill, as is more than 8
+# cores per package build.
+#
+# Example usage:
+#
+#  % ../../utils/parallel_install.sh 2 6
+# -or-
+#  % utils/parallel_install.sh 4 4 --fail-fast --verbose esmf
+
+argtext="Run as '$0 N M', where N=# of instances, M=# of threads per instance"
+n_instances=${1?"$argtext"}
+n_threads=${2?"$argtext"}
+shift 2
+
+if [[ ! " $(seq -s ' ' 10) " =~ " $n_instances " ]]; then echo "Invalid number of instances" ; exit 1; fi
+if [[ ! " $(seq -s ' ' 64) " =~ " $n_threads " ]]; then echo "Invalid number of threads" ; exit 1; fi
+
+echo "Installing with $n_instances instances and ${n_threads} threads in environment '${SPACK_ENV?"SPACK_ENV not set!"}'"
+
+for i in $(seq $n_instances); do
+  cmd="spack install -j $n_threads $*"
+  echo $cmd | tee ${SPACK_ENV}/log.install.proc${i}
+  $cmd &>> ${SPACK_ENV}/log.install.proc${i} &
+done
+
+# If running as executable:
+if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
+    wait
+fi