Prestashop Core Application V1.5
  1. Prestashop Core Application V1.5
  2. PSCFV-8899

APC, XCache and Memcached not working properly (performance decrease)

    Details

    • Type: Bug Bug
    • Status: Closed Closed
    • Resolution: Duplicate
    • Affects Version/s: None
    • Fix Version/s: None
    • Security Level: All-users
    • Labels:
      None

      Description

      Hi there. I took the time on weekend to test the different cache options in prestashop and still found no love. I suspect that there is a bug. maybe already in the Cache.php. All tests with different cache (except the smarty cache)options had negative impact on the performance. For example without memcached http://www.webpagetest.org/result/130423_S0_C2M/ ... first time byte about 1.6 seconds... with memcached http://www.webpagetest.org/result/130423_MG_C0J/ first time byte 2.8 seconds and yes the page was accessed a couple of times before so the cache could be filled. I made a lot of tests on my local machine too. All with negative results through all cache options I could test.
      All the best, trip

        Activity

        Hide
        Javier Moya added a comment -

        Since last month we have been using xcache and has been a disaster, everything was slower, and the backoffice not working properly: (Failed to install and uninstall modules, error running from the back office processes, bore no changes in the options) was disable xcache and everything returned to normal operation.

        My server has 16MB xcache not know if that is enough or should you need more.

        Show
        Javier Moya added a comment - Since last month we have been using xcache and has been a disaster, everything was slower, and the backoffice not working properly: (Failed to install and uninstall modules, error running from the back office processes, bore no changes in the options) was disable xcache and everything returned to normal operation. My server has 16MB xcache not know if that is enough or should you need more.
        Hide
        Attilio Scotolati added a comment -

        I can confirm the problem exists also with APC: enabling its option in BO causes performances to decrease, especially over time. I think the reason is cache fragmentation: after one hour of caching in a lightly accessed shop, with ~50MB of cache used out of 128, the fragmentation shown by apc.php was well over 40%, while acceptable values are said to be 10% at most.
        There must be something wrong in the way variables are saved to cache; my guess is that they are updated too often, but I'm no expert in this field...

        Show
        Attilio Scotolati added a comment - I can confirm the problem exists also with APC: enabling its option in BO causes performances to decrease, especially over time. I think the reason is cache fragmentation: after one hour of caching in a lightly accessed shop, with ~50MB of cache used out of 128, the fragmentation shown by apc.php was well over 40%, while acceptable values are said to be 10% at most. There must be something wrong in the way variables are saved to cache; my guess is that they are updated too often, but I'm no expert in this field...
        Hide
        Trip added a comment - - edited

        From my last tests I would say APC 100 Mb slight decrease in Response time. Memcached -> desaster and the rest I can not remember. I think prestashop is not the slowest but compared to XT commerce or JTL it is relativly slow, espacially rendering the category pages. I hope this can be optimized.
        When I use 20 products per page it needs Load time: 1.09s and with 40 it already goes up Load time: 1.929s ... the query time is increased by 50ms so it it not a problem with the database.
        All the best, trip

        Show
        Trip added a comment - - edited From my last tests I would say APC 100 Mb slight decrease in Response time. Memcached -> desaster and the rest I can not remember. I think prestashop is not the slowest but compared to XT commerce or JTL it is relativly slow, espacially rendering the category pages. I hope this can be optimized. When I use 20 products per page it needs Load time: 1.09s and with 40 it already goes up Load time: 1.929s ... the query time is increased by 50ms so it it not a problem with the database. All the best, trip
        Hide
        Sergio I added a comment -

        I confirm that memcached is terrible slow in 1.5.4.1

        Show
        Sergio I added a comment - I confirm that memcached is terrible slow in 1.5.4.1
        Hide
        Gregory Roussac added a comment - - edited

        Dear all,

        This subject will be grouped on http://forge.prestashop.com/browse/PSCFV-5225

        All cache classes must be rewritten to handle LRU algorithm.

        Thanks. regards

        Show
        Gregory Roussac added a comment - - edited Dear all, This subject will be grouped on http://forge.prestashop.com/browse/PSCFV-5225 All cache classes must be rewritten to handle LRU algorithm. Thanks. regards

          People

          • Assignee:
            Gregory Roussac
            Reporter:
            Trip
          • Votes:
            3 Vote for this issue
            Watchers:
            0 Start watching this issue

            Dates

            • Created:
              Updated:
              Resolved: