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#!/bin/bash
#
# Script for running java with a timeout.
#
# The timeout in seconds must be the first argument. The rest of the arguments
# are passed to the java binary itself.
#
# For example:
# java-timeout 120 -cp classes.jar org.junit.runner.JUnitCore
# runs:
# java -cp classes.jar org.junit.runner.JUnitCore
# with a timeout of 2 minutes.
set -euo pipefail
# Prints a message and terminates the process.
function fatal() {
echo "FATAL: $*"
exit 113
}
# Function that is invoked if java is terminated due to timeout.
# It take the process ID of the java command as an argument if it has already
# been started, or the empty string if not. It should very rarely receive the
# empty string as the pid, but it is possible.
function on_timeout() {
echo 'FATAL: command timed out'
local pid="${1-}"
shift || fatal '[on_timeout] missing argument: pid'
test $# = 0 || fatal '[on_timeout] too many arguments'
if [ "$pid" != '' ]; then
# It is possible that the process already terminated, but there is not much
# we can do about that.
kill -TERM -- "-$pid" # Kill the entire process group.
fi
}
# Executes java with the given argument, waiting for a termination signal from
# runalarm which this script is running under. The arguments are passed to the
# java binary itself.
function execute() {
# Trap SIGTERM, which is what we will receive if runalarm interrupts us.
local pid # Set below after we run the process.
trap 'on_timeout $pid' SIGTERM
# Starts java within a new process group and saves it process ID before
# blocking waiting for it to complete. 'setsid' starts the process within a
# new process group, which means that it will not be killed when this shell
# command is killed. This is needed so that the signal handler in the trap
# command above to be invoked before the java command is terminated (and will
# in fact have to terminate it itself).
setsid -w java "$@" & pid="$!"; wait "$pid"
}
# Runs java with a timeout. The first argument is either the timeout in seconds
# or the string 'execute', which is used internally to execute the command under
# runalarm.
function main() {
local timeout_secs="${1-}"
shift || fatal '[main]: missing argument: timeout_secs'
# The reset of the arguments are meant for the java binary itself.
if [[ $timeout_secs = '0' ]]; then
# Run without any timeout.
java "$@"
elif [[ $timeout_secs = 'execute' ]]; then
# This means we actually have to execute the command.
execute "$@"
elif (( timeout_secs < 30 )); then
# We want to have a timeout of at least 30 seconds, so that we are
# guaranteed to be able to start the java command in the subshell. This also
# catches non-numeric arguments.
fatal 'Must specify a timeout of at least 30 seconds.'
else
# Wrap the command with the standard timeout(1) if available.
# "runalarm" is a Google timeout clone, and Mac users who've installed
# GNU coreutils have timeout available as "gtimeout".
if type timeout > /dev/null 2>&1 ; then
timeout "${timeout_secs}" "$0" 'execute' "$@"
elif type runalarm > /dev/null 2>&1 ; then
runalarm -t "$timeout_secs" "$0" 'execute' "$@"
elif type gtimeout > /dev/null 2>&1 ; then
gtimeout "${timeout_secs}s" "$0" 'execute' "$@"
else
# No way to set a timeout available, just execute directly.
echo "Warning: unable to enforce timeout." 1>&2
java "$@"
fi
fi
}
main "$@"