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  1. MariaDB Server
  2. MDEV-35125

Unnecessary buf_pool.page_hash lookups

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    Description

      In the function btr_blob_free() there is an unnecessary lookup of buf_pool.page_hash. If we acquired an additional buffer-fix on the page before mtr_t::commit() and released it after acquiring buf_pool.mutex, we would know that the page still exists in the buffer pool and can be attempted to be freed, without having to look it up in buf_pool.page_hash again.

      There could be similar suboptimal patterns elsewhere as well.

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          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-33966 sysbench performance regression with concurrent workloads

          • Critical - Crashes, loss of data, severe memory leak.
          • Stalled

          Bug - A problem which impairs or prevents the functions of the product. MDEV-34791 Redundant page lookups hurt performance

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Activity

            marko Marko Mäkelä added a comment -

            Apart from btr_blob_free(), I found some avoidable look-ups for an index root page and duplicated error handling in dict_load_table_one(). Furthermore, trx_t::apply_log() could do without a mini-transaction, just invoking the recently added buf_pool.page_fix() to access the undo log pages that are in the exclusive ownership of the active transaction.

            marko Marko Mäkelä added a comment - Apart from btr_blob_free() , I found some avoidable look-ups for an index root page and duplicated error handling in dict_load_table_one() . Furthermore, trx_t::apply_log() could do without a mini-transaction, just invoking the recently added buf_pool.page_fix() to access the undo log pages that are in the exclusive ownership of the active transaction.

            People

              thiru Thirunarayanan Balathandayuthapani
              marko Marko Mäkelä
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