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  1. Moodle
  2. MDL-40538

cachestore_static, cachestore_session: array_key_exists slow

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    • MOODLE_24_STABLE, MOODLE_25_STABLE
    • MOODLE_24_STABLE, MOODLE_25_STABLE
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      Before application (or revert if possible)

      1. site administration > settings > plugins > caching > test performance
      2. Run performance test with 10000 unique queries. Note the times for "session" and "static request" caches

      Apply Patch/ensure it's installed

      1. site administration > settings > plugins > caching > test performance
      2. Run performance test with 10000 unique queries. Note the times for "session" and "static request" caches

      3. Compare times

      4. Run phpunit tests.

      Please note that performance improvements will vary on the platform you test this on. For example time() performance varies depending on system architecture, eg VM or physical. array_key_exists will depending on CPU caches and may other things.

      On KVM on AMD Athlon(tm) 64 X2 Dual Core Processor 5200+ gave a 100x increase for hits on static cache.

      Show
      Before application (or revert if possible) 1. site administration > settings > plugins > caching > test performance 2. Run performance test with 10000 unique queries. Note the times for "session" and "static request" caches Apply Patch/ensure it's installed 1. site administration > settings > plugins > caching > test performance 2. Run performance test with 10000 unique queries. Note the times for "session" and "static request" caches 3. Compare times 4. Run phpunit tests. Please note that performance improvements will vary on the platform you test this on. For example time() performance varies depending on system architecture, eg VM or physical. array_key_exists will depending on CPU caches and may other things. On KVM on AMD Athlon(tm) 64 X2 Dual Core Processor 5200+ gave a 100x increase for hits on static cache.

      array_key_exists can be slow and can add substantial overhead to calls.

      time() can be an expensive call on some platforms.

      There calls should be out of the critical path in the static cache.

        1. cache_static_isset_with_array_key_exists.png
          cache_static_isset_with_array_key_exists.png
          283 kB
        2. cache_static_no_change.png
          cache_static_no_change.png
          147 kB

            mr-russ Russell Smith
            mr-russ Russell Smith
            Sam Hemelryk Sam Hemelryk
            Damyon Wiese Damyon Wiese
            Michael de Raadt Michael de Raadt
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            1 Vote for this issue
            Watchers:
            4 Start watching this issue

              Created:
              Updated:
              Resolved:

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