One of our Magento clients has reported that creating orders from the backend (manually eg customer ordering over the phone) is intermittently very slow.
Each checkout step (whenever the spinning 'Please wait' wheel appears) can take anywhere from 5-20s to load:
To check/confirm this we have installed AOE Profiler and have set it to profile the requests made to the
The profiler has identified that the most common source of slowness is the
Mage_Core_Model_Session_Abstract_Varien::start/start event. We have seen that event take between 5-40s as shown in the screenshot below:
Saving an order can take anywhere from 10-40 seconds (10s is normal whereas anything greater than 15s is excessive). MySQL slow query logging is enabled and it has not logged any slow queries so the slowness does not appear to be due to database queries.
The system has 12,000 products and approx 10,000 orders. Most orders only have 2-3 order items.
The site is running Magento 184.108.40.206 on dedicated hardware and the system load is always low (eg < 0.5). The site gets low traffic and there is rarely more than 1 customer browsing at a time so there does not appear to be a bottleneck as far as resource allocation is concerned.
Additional information requested:
- MySQL server is hosted locally on same dedicated server as web server
- MySQL version is 5.1.73 (most recent version supported by CentOS 6.10)
- RAM is 64GB (~40GB currently free)
- my.cnf: https://pastebin.com/Dq2jYKDa
- SHOW GLOBAL STATUS result: https://pastebin.com/Bmy7B8n5
- SHOW GLOBAL VARIABLES result: https://pastebin.com/fghk0UkL
- MySQLTuner output: https://pastebin.com/xqKzCSxd
- Other commands: https://pastebin.com/D3TFMae9
How can we troubleshoot/fix the slow session start which is causing the slowness?