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  1. MariaDB Server
  2. MDEV-32374

log_sys.lsn_lock is a performance hog

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    Description

      MDEV-27774 made it possible to for multiple mtr_t::commit() to write to log_sys.buf concurrently, by replacing the InnoDB log_sys.mutex with log_sys.latch and log_sys.lsn_lock. The latter appears to be a performance bottleneck.

      Because we need to keep multiple log_sys data members consistent with each other, we cannot simply invoke std::atomic::fetch_add and std::atomic::compare_exchange_weak on log_sys.buf_free to achieve a similar result. But, we could try to fit more data members in the same single cache line with log_sys.latch.

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          is caused by

          Bug - A problem which impairs or prevents the functions of the product. MDEV-27774 Reduce scalability bottlenecks in mtr_t::commit()

          • Major - Major loss of function.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-27866 Switching log_sys.latch to use spin based variant

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-33515 log_sys.lsn_lock causes excessive context switching

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

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              marko Marko Mäkelä
              marko Marko Mäkelä
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                Resolved:

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