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  1. MariaDB Server
  2. MDEV-17874

MyRocks-Gap-Lock: Lock memory overhead

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    Description

      Several MyRocks tests currently fail, because they reach rocksdb_max_lock_memory and lock escalation is unable to reduce memory usage.

      One example is autoinc_vars_thread_2. AUTO_INCREMENT values are generated by each thread using auto_increment_offset which causes all adjacent row locks to belong to different transactions.

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          Task - A task that needs to be done. MDEV-15603 Gap Lock support in MyRocks

          • Major - Major loss of function.
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            psergei Sergei Petrunia added a comment -

            in spetrunia/mysql-5.6-rangelocking 

            toku::concurrent_tree::get_insertion_memory_overhead()=176

            in Percona Server:

             
            toku::concurrent_tree::get_insertion_memory_overhead()=192

            Add to that keyrange::get_memory_size() which is (sizeof(key_range)=72) + left_key_size +right_key_size (they are intentionally counted twice).

            In total, for pk INT PRIMARY KEY the lock memory usage is 264 bytes in 5.6-rangelocking (debug build) and 274 in debug build of Percona Server.

            psergei Sergei Petrunia added a comment - in spetrunia/mysql-5.6-rangelocking toku::concurrent_tree::get_insertion_memory_overhead()=176 in Percona Server: toku::concurrent_tree::get_insertion_memory_overhead()=192 Add to that keyrange::get_memory_size() which is (sizeof(key_range)=72) + left_key_size +right_key_size (they are intentionally counted twice). In total, for pk INT PRIMARY KEY the lock memory usage is 264 bytes in 5.6-rangelocking (debug build) and 274 in debug build of Percona Server.
            psergei Sergei Petrunia added a comment -

            In Percona Server's MTR environment: tokudb_max_lock_memory is not set, so tokudb_init_func sets it to 1/8 th of tokudb-cache-size which is 512M, so we get 64M.

            In MariaDB, the default value is tokudb_max_lock_memory = 1 035 604 992= 1G

            psergei Sergei Petrunia added a comment - In Percona Server's MTR environment: tokudb_max_lock_memory is not set, so tokudb_init_func sets it to 1/8 th of tokudb-cache-size which is 512M, so we get 64M. In MariaDB, the default value is tokudb_max_lock_memory = 1 035 604 992= 1G

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              psergei Sergei Petrunia
              psergei Sergei Petrunia
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