This script identifies the second most memory-intensive PHP process, resets the Out-Of-Memory (OOM) priority of the previously adjusted process if still running, sets the current process's OOM priority to be more likely killed, and logs its PID and timestamp.

oom_score_adj.sh

#!/bin/bash

APP="php"
CURRENT_HIGHEST=$(ps -eo pid,comm --sort=-%mem | grep "$APP" | head -n 2 | tail -n 1)
CURRENT_HIGHEST_PID=$(echo $CURRENT_HIGHEST | awk '{print $1'})
LAST_PID_FILE="/tmp/oom-kill-previous"

if [ -f "$LAST_PID_FILE" ]; then
    LAST_PID=$(cat $LAST_PID_FILE)

    if [ "$LAST_PID" != "" ] && [ -d "/proc/$LAST_PID" ]; then
        echo 0 > /proc/$LAST_PID/oom_score_adj
    fi
fi

echo 1000 > /proc/$CURRENT_HIGHEST_PID/oom_score_adj
echo $CURRENT_HIGHEST_PID > $LAST_PID_FILE

echo "[$(date --iso-8601=seconds)] $CURRENT_HIGHEST"