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  1. MariaDB Server
  2. MDEV-466

Galera: Excessive memory use on sizable transactions

Details

    • Bug
    • Status: Closed (View Workflow)
    • Major
    • Resolution: Not a Bug
    • None
    • 5.5.25-galera
    • None
    • None

    Description

      I execute the following set of statements 3 times in a row:

        CREATE TABLE t1 ( a INT NOT NULL AUTO_INCREMENT PRIMARY KEY, b INT NOT NULL) ;
      		 
        INSERT INTO t1 (b) VALUES (1),(2),(3),(4),(5),(6),(7),(8);
      		 
        INSERT INTO t1 (b) SELECT t1a.b FROM t1 t1a, t1 t1b, t1 t1c, t1 t1d, t1 t1e, t1 t1f LIMIT 131064;
      		 
        SELECT COUNT(*) FROM t1;
      		 
        DROP TABLE t1;

      wait for innodb to settle (for checkpoint age to become 0), and check memory consumption after each round.

      Here are results for a server started in Galera context (as a new node):

      Server options:

      --innodb --default-storage-engine=innodb --innodb_autoinc_lock_mode=2 --innodb_locks_unsafe_for_binlog=1 --innodb_flush_log_at_trx_commit=0 --innodb_doublewrite=0 --binlog-format=row --log-bin=master-bin --wsrep_provider=/home/elenst/galera-23.2.1-src/libgalera_smm.so --wsrep_cluster_address=gcomm://?'gmcast.listen_addr=tcp://127.0.0.1:4567'
      		 

        PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
      		 
      # Start
      		 
      17380 elenst    20   0  863m 345m 9.8m S    0  4.3   0:00.47 mysqld
      		 
      # After the 1st round
      		 
      17380 elenst    20   0 1060m 603m  14m S    0  7.5   0:35.33 mysqld
      		 
      # After the 2nd round
      		 
      17380 elenst    20   0 1124m 648m  18m S    0  8.1   1:05.34 mysqld
      		 
      # After the 3rd round
      		 
      17380 elenst    20   0 1126m 659m  21m S    1  8.2   1:35.49 mysqld

      So, we started and ended at the same point (dropped the table that we previously created and populated), however memory consumption has grown ~260 Mb

      Nothing like that happens if the server is run in a standalone mode (with otherwise the same parameters):

      Server options:

      --innodb --default-storage-engine=innodb --innodb_autoinc_lock_mode=2 --innodb_locks_unsafe_for_binlog=1 --innodb_flush_log_at_trx_commit=0 --innodb_doublewrite=0 --binlog-format=row --log-bin=master-bin 

        PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
      		 
      # Start
      		 
      17336 elenst    20   0  611m 318m 7468 S    0  4.0   0:02.41 mysqld 
      # After the 1st round
      		 
      17336 elenst    20   0  615m 329m 9268 S    0  4.1   0:08.40 mysqld 
      # After the 2nd round
      		 
      17336 elenst    20   0  615m 334m 9316 S    0  4.2   0:14.28 mysqld
      		 
      # After the 3rd round
      		 
      17336 elenst    20   0  615m 340m 9316 S    0  4.3   0:20.05 mysqld

      bzr version-info:

      revision-id: seppo.jaakola@codership.com-20120808224721-89h8nxmfk9uvp708
      		 
      date: 2012-08-09 01:47:21 +0300
      		 
      build-date: 2012-08-20 07:00:22 +0400
      		 
      revno: 3343

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            seppo Seppo Jaakola
            elenst Elena Stepanova
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              Created:
              Updated:
              Resolved:

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