PHP Memory Usage Log

memory-usage-log.md

Setup memory log on php-fpm pool

1. Added the following to /usr/local/lib/strangecode_php_memory_log.php

    <?php
    function strangecode_php_memory_log()
    {
        $current = memory_get_usage() / 1024 / 1024;
        $peak = memory_get_peak_usage() / 1024 / 1024;
        $uri = $_SERVER['REQUEST_URI'] ?? 'n/a';
        $message = sprintf("current: %6.1f MB peak: %6.1f MB uri: %s\n", $current, $peak, $uri);
        error_log($message, 3, '/var/log/php-fpm/php_memory.log');
    }
    register_shutdown_function('strangecode_php_memory_log');
   

2. Created the log and set permissions to allow writing from anywhere

    touch /var/log/php-fpm/php_memory.log
    chmod 666 /var/log/php-fpm/php_memory.log
   

3. Added following to /etc/php-fpm.d/www-prod.conf

    php_admin_value[auto_prepend_file] = /usr/local/lib/strangecode_php_memory_log.php
   

Log parse/sort commands

# average the memory columns across entire log file
awk '{sum+=$5} END {print sum/NR,"MB/request (peak average)"}' /var/log/php-fpm/php_memory.log
awk '{sum+=$2} END {print sum/NR,"MB/request (average)"}' /var/log/php-fpm/php_memory.log

# sort by uri
sort -t/ -k2 /var/log/php-fpm/php_memory.log | less

# descending sort by peak memory usage column
sort -rnk5 /var/log/php-fpm/php_memory.log | less

# descending sort by current (i.e. during shutdown) memory usage column
sort -rnk2 /var/log/php-fpm/php_memory.log | less