Build retry loop for screen sessions
There is a timing window where we might lose the commands being stuffed into screen because bash is spawning. In those cases, loop around and try building screen sessions again. Change-Id: I49247de06bbd59424cb10fb9a8db145907be5138 Related-Bug: #1331274
This commit is contained in:
Sean Dague
parent
af86e43d7b
commit
0afa912e99
112
functions-common
112
functions-common
@ -1058,44 +1058,100 @@ function run_process {
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echo $!
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}
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function _start_in_screen {
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local service=$1
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local cmd=$2
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local screen_name=${SCREEN_NAME:-stack}
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local status_dir=${SERVICE_DIR:-${DEST}/status}
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local service_dir="$status_dir/$screen_name"
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local pid="$service_dir/$service.pid"
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local failure="$service_dir/$service.failure"
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if [[ -n ${SCREEN_LOGDIR} ]]; then
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local logfile=${SCREEN_LOGDIR}/screen-${service}.${CURRENT_LOG_TIME}.log
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local shortlog=${SCREEN_LOGDIR}/screen-${service}.log
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# this whole dance is done because of slow nodes
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screen -S $screen_name -p $service -X logfile ${logfile}
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screen -S $screen_name -p $service -X log on
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ln -sf ${logfile} ${shortlog}
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fi
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NL=`echo -ne '\015'`
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# This fun command does the following:
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# - the passed server command is backgrounded
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# - the pid of the background process is saved in the usual place
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# - the server process is brought back to the foreground
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# - if the server process exits prematurely the fg command errors
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# and a message is written to stdout and the service failure file
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# The pid saved can be used in screen_stop() as a process group
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# id to kill off all child processes
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echo "Running: $cmd & echo \$! >$pid; fg || echo \"$service failed to start\" | tee \"$failure\"$NL"
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screen -S $screen_name -p $service -X stuff "$cmd & echo \$! >$pid; fg || echo \"$service failed to start\" | tee \"$failure\"$NL"
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}
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function _is_running_in_screen {
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local service=$1
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local screen_name=${SCREEN_NAME:-stack}
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local status_dir=${SERVICE_DIR:-${DEST}/status}
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local service_dir="$status_dir/$screen_name"
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local pid="$service_dir/$service.pid"
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local failure="$service_dir/$service.failure"
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if [[ ! -e "$pid" && ! -e "$failure" ]]; then
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# if we don't have a pid or a failure for why, the command may not
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# have stuffed in there
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echo "Warning: neither $pid nor $failure exist, $service didn't seem to start"
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return 1
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fi
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if [[ -n ${SCREEN_LOGDIR} ]]; then
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# if we should be logging, but we don't have a log file, something is wrong
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local logfile=${SCREEN_LOGDIR}/screen-${service}.${CURRENT_LOG_TIME}.log
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if [[ ! -e "$logfile" ]]; then
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echo "Warning: expected logfile $logfile not found, something wrong with starting $service"
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return 1
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fi
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fi
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return 0
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}
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# Helper to launch a service in a named screen
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# screen_it service "command-line"
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function screen_it {
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SCREEN_NAME=${SCREEN_NAME:-stack}
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SERVICE_DIR=${SERVICE_DIR:-${DEST}/status}
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USE_SCREEN=$(trueorfalse True $USE_SCREEN)
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local service=$1
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local cmd=$2
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local screen_name=${SCREEN_NAME:-stack}
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local status_dir=${SERVICE_DIR:-${DEST}/status}
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local service_dir="$status_dir/$screen_name"
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local use_screen=$(trueorfalse True $USE_SCREEN)
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local pid="$service_dir/$service.pid"
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if is_service_enabled $1; then
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# Append the service to the screen rc file
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screen_rc "$1" "$2"
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screen_rc "$service" "$cmd"
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if [[ "$USE_SCREEN" = "True" ]]; then
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screen -S $SCREEN_NAME -X screen -t $1
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if [[ "$use_screen" = "True" ]]; then
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screen -S $screen_name -X screen -t $service
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if [[ -n ${SCREEN_LOGDIR} ]]; then
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screen -S $SCREEN_NAME -p $1 -X logfile ${SCREEN_LOGDIR}/screen-${1}.${CURRENT_LOG_TIME}.log
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screen -S $SCREEN_NAME -p $1 -X log on
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ln -sf ${SCREEN_LOGDIR}/screen-${1}.${CURRENT_LOG_TIME}.log ${SCREEN_LOGDIR}/screen-${1}.log
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fi
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# sleep to allow bash to be ready to be send the command - we are
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# creating a new window in screen and then sends characters, so if
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# bash isn't running by the time we send the command, nothing happens
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sleep 3
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NL=`echo -ne '\015'`
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# This fun command does the following:
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# - the passed server command is backgrounded
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# - the pid of the background process is saved in the usual place
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# - the server process is brought back to the foreground
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# - if the server process exits prematurely the fg command errors
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# and a message is written to stdout and the service failure file
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# The pid saved can be used in screen_stop() as a process group
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# id to kill off all child processes
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screen -S $SCREEN_NAME -p $1 -X stuff "$2 & echo \$! >$SERVICE_DIR/$SCREEN_NAME/$1.pid; fg || echo \"$1 failed to start\" | tee \"$SERVICE_DIR/$SCREEN_NAME/$1.failure\"$NL"
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# this retry loop brought to you by slow compute nodes, screen raciness,
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# and frustration in upgrading.
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local screen_tries=0
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while [ "$screen_tries" -lt 10 ]; do
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_start_in_screen "$service" "$cmd"
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if _is_running_in_screen $service; then
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screen_tries=10
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else
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screen_tries=$[screen_tries + 1]
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echo "Failed to start service after $screen_tries attempt(s), retrying"
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if [[ "$screen_tries" -eq 10 ]]; then
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echo "Too many retries, giving up"
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exit 1
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fi
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sleep 1
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fi
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done
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else
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# Spawn directly without screen
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run_process "$1" "$2" >$SERVICE_DIR/$SCREEN_NAME/$1.pid
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run_process "$service" "$cmd" >$pid
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fi
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fi
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}
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