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  1. Core Server
  2. SERVER-17035

fix text for "pages evicted by application threads" in WiredTiger

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    Details

    • Type: Task
    • Status: Closed
    • Priority: Minor - P4
    • Resolution: Duplicate
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: None
    • Labels:
      None
    • Backwards Compatibility:
      Fully Compatible

      Description

      This is the cache section from db.serverStatus() after running a busy workload for about a few minutes. Note that mongod was started immediately prior to the test.

      How can this possibly be true after a few minutes?
      "pages evicted by application threads" : 3938125731,

      I thought that maybe it counted bytes, which is possible given:
      "bytes written from cache" : 4421343996,

      But from looking at the code it just counts the number of calls to __wt_evict_lru_page

      /*
       * __wt_evict_lru_page --
       *      Called by both eviction and application threads to evict a page.
       */
      int
      __wt_evict_lru_page(WT_SESSION_IMPL *session, int is_app)
      {
              WT_BTREE *btree;
              WT_CACHE *cache;
              WT_DECL_RET;
              WT_PAGE *page;
              WT_REF *ref;
       
              if (is_app)
                      WT_STAT_FAST_CONN_INCR(session, cache_eviction_app);

                      "cache" : {
                              "tracked dirty bytes in the cache" : 488305732,
                              "bytes currently in the cache" : 857590757,
                              "maximum bytes configured" : 1073741824,
                              "bytes read into cache" : 6992771243,
                              "bytes written from cache" : 4421343996,
                              "pages evicted by application threads" : 3938125731,
                              "checkpoint blocked page eviction" : 3,
                              "unmodified pages evicted" : 199580,
                              "page split during eviction deepened the tree" : 1,
                              "modified pages evicted" : 65810,
                              "pages selected for eviction unable to be evicted" : 941,
                              "pages evicted because they exceeded the in-memory maximum" : 400,
                              "pages evicted because they had chains of deleted items" : 2,
                              "failed eviction of pages that exceeded the in-memory maximum" : 0,
                              "hazard pointer blocked page eviction" : 20,
                              "internal pages evicted" : 0,
                              "maximum page size at eviction" : 42848801,
                              "eviction server candidate queue empty when topping up" : 1092,
                              "eviction server candidate queue not empty when topping up" : 11153,
                              "eviction server evicting pages" : 59,
                              "eviction server populating queue, but not evicting pages" : 12186,
                              "eviction server unable to reach eviction goal" : 0,
                              "pages split during eviction" : 3919,
                              "pages walked for eviction" : 9457046,
                              "in-memory page splits" : 133,
                              "tracked dirty pages in the cache" : 7550,
                              "pages currently held in the cache" : 14340,
                              "pages read into cache" : 279087,
                              "pages written from cache" : 221121
                      },

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                • Created:
                  Updated:
                  Resolved: