Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-10455

libmariadbclient18 + MySQL-python leaks memory on failed connections

Details

    Description

      When MySQLdb (python-mysqldb) uses the MariaDB libmysqlclient.so.18 libraries, it seems to leak memory with each failed connection. A simple contrived loop (w/ mariadb stopped, generating client 2003 errors) leads to a few GB RSS for the associated python process in a few seconds when using the MariaDB 10.1 client packages:

      #!/usr/bin/env python
      		 
       
      		 
      import resource
      		 
      import time
      		 
       
      		 
      import MySQLdb
      		 
       
      		 
      print("Client version: %s" % MySQLdb.get_client_info())
      		 
       
      		 
      max_allowed_rss = 512*1024
      		 
      failed_connects = 0
      		 
      initial_rss = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
      		 
       
      		 
      for _ in xrange(50000):
      		 
          try:
      		 
              MySQLdb.connect(user='root', host='127.0.0.1')
      		 
          except MySQLdb.Error:
      		 
              failed_connects += 1
      		 
       
      		 
      print("maxrss initial was: %sKB, final is %sKB; %.2fMiB change after %d failed connections." %
      		 
              (
      		 
              initial_rss,
      		 
              resource.getrusage(resource.RUSAGE_SELF).ru_maxrss,
      		 
              (resource.getrusage(resource.RUSAGE_SELF).ru_maxrss - initial_rss) / 1024.0,
      		 
              failed_connects
      		 
              )
      		 
          )

      The output of running this is as follows:

      $ apt-get install libmysqlclient18=5.5.50-0+deb8u1
      		 
      $ python mdev10455_mysqldb_memleak.py
      		 
      Client version: 5.5.50
      		 
      maxrss initial was: 8364KB, final is 10044KB; 1.64MiB change after 50000 failed connections.
      		 
       
      		 
      $ apt-get install libmysqlclient18=5.6.30-1~bpo8+1
      		 
      $ python mdev10455_mysqldb_memleak.py
      		 
      Client version: 5.6.30
      		 
      maxrss initial was: 8536KB, final is 10216KB; 1.64MiB change after 50000 failed connections.
      		 
       
      		 
      $ apt-get install libmysqlclient18=10.1.16+maria-1~jessie
      		 
      $ python mdev10455_mysqldb_memleak.py
      		 
      Client version: 10.1.16-MariaDB
      		 
      maxrss initial was: 9272KB, final is 437896KB; 418.58MiB change after 50000 failed connections.

      Removing libmariadbclient18 and reverting to the libmysqlclient18 provided by either MySQL 5.5 (5.5.50-0+deb8u1) (debian/jessie main) or MySQL 5.6 (5.6.30-1~bpo8+1 from jessie-backports), the memory leak goes away and memory use stays constant over time.

      I see MySQL-python does not call mysql_close() on a failed connection which seems to resolve this behavior with MariaDB - so perhaps this is an incorrect API usage bug. However the MariaDB behavior does seem to differ from the MySQL (5.5.50, 5.6.30) behavior, so I am opening this issue.

      Attachments

        Issue Links

          relates to

          Task - A task that needs to be done. MDEV-10546 Make unit tests run with valgrind

          • Major - Major loss of function.
          • Open

          Task - A task that needs to be done. MDEV-10546 Make unit tests run with valgrind

          • Major - Major loss of function.
          • Open

          Activity

            Ascending order - Click to sort in descending order
            andrew.garner Andrew Garner created issue -
            andrew.garner Andrew Garner made changes -
            Field Original Value New Value
            Description When MySQLdb (python-mysqldb) uses the MariaDB libmysqlclient.so.18 libraries, it seems to leak memory with each failed connection. A simple contrived loop (w/ mariadb stopped, generating client 2003 errors) leads to a few GB RSS for the associated python process in a few seconds when using the MariaDB 10.1 client packages:

            {code:python}
            import MySQLdb

            while True:
                try:
                    MySQLdb.connect(user='root')
                except MySQLdb.Error:
                    pass
            {code}

            Removing libmariadbclient18 and reverting to the libmysqlclient18 provided by either MySQL 5.5 (5.5.50-0+deb8u1) (debian/jessie main) or MySQL 5.6 (5.6.30-1~bpo8+1 from jessie-backports), the memory leak goes away and memory use stays constant over time.

            I see MySQL-python does not call mysql_close() on a failed connection which seems to resolve this behavior with MariaDB - so perhaps this is an incorrect API usage bug. However the MariaDB behavior does seem to differ from the MySQL (5.5.50, 5.6.30) behavior, so I am opening this issue.
            		When MySQLdb (python-mysqldb) uses the MariaDB libmysqlclient.so.18 libraries, it seems to leak memory with each failed connection. A simple contrived loop (w/ mariadb stopped, generating client 2003 errors) leads to a few GB RSS for the associated python process in a few seconds when using the MariaDB 10.1 client packages:

            {code:python}
            #!/usr/bin/env python

            import resource
            import time

            import MySQLdb

            print("Client version: %s" % MySQLdb.get_client_info())

            max_allowed_rss = 512*1024
            failed_connects = 0
            initial_rss = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss

            for _ in xrange(50000):
            #while resource.getrusage(resource.RUSAGE_SELF).ru_maxrss < max_allowed_rss:
                try:
                    MySQLdb.connect(user='root', host='127.0.0.1')
                except MySQLdb.Error:
                    failed_connects += 1

            print("maxrss initial was: %sKB, final is %sKB; %.2fMiB change after %d failed connections." %
                    (
                    initial_rss,
                    resource.getrusage(resource.RUSAGE_SELF).ru_maxrss,
                    (resource.getrusage(resource.RUSAGE_SELF).ru_maxrss - initial_rss) / 1024.0,
                    failed_connects
                    )
                )
            {code}

            The output of running this is as follows:
            {noformat}
            $ apt-get install libmysqlclient18=5.5.50-0+deb8u1
            $ python mdev10455_mysqldb_memleak.py
            Client version: 5.5.50
            maxrss initial was: 8364KB, final is 10044KB; 1.64MiB change after 50000 failed connections.

            $ apt-get install libmysqlclient18=5.6.30-1~bpo8+1
            $ python mdev10455_mysqldb_memleak.py
            Client version: 5.6.30
            maxrss initial was: 8536KB, final is 10216KB; 1.64MiB change after 50000 failed connections.

            $ apt-get install libmysqlclient18=10.1.16+maria-1~jessie
            $ python mdev10455_mysqldb_memleak.py
            Client version: 10.1.16-MariaDB
            maxrss initial was: 9272KB, final is 437896KB; 418.58MiB change after 50000 failed connections.

            {noformat}


            Removing libmariadbclient18 and reverting to the libmysqlclient18 provided by either MySQL 5.5 (5.5.50-0+deb8u1) (debian/jessie main) or MySQL 5.6 (5.6.30-1~bpo8+1 from jessie-backports), the memory leak goes away and memory use stays constant over time.

            I see MySQL-python does not call mysql_close() on a failed connection which seems to resolve this behavior with MariaDB - so perhaps this is an incorrect API usage bug. However the MariaDB behavior does seem to differ from the MySQL (5.5.50, 5.6.30) behavior, so I am opening this issue.
            andrew.garner Andrew Garner made changes -
            Description When MySQLdb (python-mysqldb) uses the MariaDB libmysqlclient.so.18 libraries, it seems to leak memory with each failed connection. A simple contrived loop (w/ mariadb stopped, generating client 2003 errors) leads to a few GB RSS for the associated python process in a few seconds when using the MariaDB 10.1 client packages:

            {code:python}
            #!/usr/bin/env python

            import resource
            import time

            import MySQLdb

            print("Client version: %s" % MySQLdb.get_client_info())

            max_allowed_rss = 512*1024
            failed_connects = 0
            initial_rss = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss

            for _ in xrange(50000):
            #while resource.getrusage(resource.RUSAGE_SELF).ru_maxrss < max_allowed_rss:
                try:
                    MySQLdb.connect(user='root', host='127.0.0.1')
                except MySQLdb.Error:
                    failed_connects += 1

            print("maxrss initial was: %sKB, final is %sKB; %.2fMiB change after %d failed connections." %
                    (
                    initial_rss,
                    resource.getrusage(resource.RUSAGE_SELF).ru_maxrss,
                    (resource.getrusage(resource.RUSAGE_SELF).ru_maxrss - initial_rss) / 1024.0,
                    failed_connects
                    )
                )
            {code}

            The output of running this is as follows:
            {noformat}
            $ apt-get install libmysqlclient18=5.5.50-0+deb8u1
            $ python mdev10455_mysqldb_memleak.py
            Client version: 5.5.50
            maxrss initial was: 8364KB, final is 10044KB; 1.64MiB change after 50000 failed connections.

            $ apt-get install libmysqlclient18=5.6.30-1~bpo8+1
            $ python mdev10455_mysqldb_memleak.py
            Client version: 5.6.30
            maxrss initial was: 8536KB, final is 10216KB; 1.64MiB change after 50000 failed connections.

            $ apt-get install libmysqlclient18=10.1.16+maria-1~jessie
            $ python mdev10455_mysqldb_memleak.py
            Client version: 10.1.16-MariaDB
            maxrss initial was: 9272KB, final is 437896KB; 418.58MiB change after 50000 failed connections.

            {noformat}


            Removing libmariadbclient18 and reverting to the libmysqlclient18 provided by either MySQL 5.5 (5.5.50-0+deb8u1) (debian/jessie main) or MySQL 5.6 (5.6.30-1~bpo8+1 from jessie-backports), the memory leak goes away and memory use stays constant over time.

            I see MySQL-python does not call mysql_close() on a failed connection which seems to resolve this behavior with MariaDB - so perhaps this is an incorrect API usage bug. However the MariaDB behavior does seem to differ from the MySQL (5.5.50, 5.6.30) behavior, so I am opening this issue.
            		When MySQLdb (python-mysqldb) uses the MariaDB libmysqlclient.so.18 libraries, it seems to leak memory with each failed connection. A simple contrived loop (w/ mariadb stopped, generating client 2003 errors) leads to a few GB RSS for the associated python process in a few seconds when using the MariaDB 10.1 client packages:

            {code:python}
            #!/usr/bin/env python

            import resource
            import time

            import MySQLdb

            print("Client version: %s" % MySQLdb.get_client_info())

            max_allowed_rss = 512*1024
            failed_connects = 0
            initial_rss = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss

            for _ in xrange(50000):
                try:
                    MySQLdb.connect(user='root', host='127.0.0.1')
                except MySQLdb.Error:
                    failed_connects += 1

            print("maxrss initial was: %sKB, final is %sKB; %.2fMiB change after %d failed connections." %
                    (
                    initial_rss,
                    resource.getrusage(resource.RUSAGE_SELF).ru_maxrss,
                    (resource.getrusage(resource.RUSAGE_SELF).ru_maxrss - initial_rss) / 1024.0,
                    failed_connects
                    )
                )
            {code}

            The output of running this is as follows:
            {noformat}
            $ apt-get install libmysqlclient18=5.5.50-0+deb8u1
            $ python mdev10455_mysqldb_memleak.py
            Client version: 5.5.50
            maxrss initial was: 8364KB, final is 10044KB; 1.64MiB change after 50000 failed connections.

            $ apt-get install libmysqlclient18=5.6.30-1~bpo8+1
            $ python mdev10455_mysqldb_memleak.py
            Client version: 5.6.30
            maxrss initial was: 8536KB, final is 10216KB; 1.64MiB change after 50000 failed connections.

            $ apt-get install libmysqlclient18=10.1.16+maria-1~jessie
            $ python mdev10455_mysqldb_memleak.py
            Client version: 10.1.16-MariaDB
            maxrss initial was: 9272KB, final is 437896KB; 418.58MiB change after 50000 failed connections.

            {noformat}


            Removing libmariadbclient18 and reverting to the libmysqlclient18 provided by either MySQL 5.5 (5.5.50-0+deb8u1) (debian/jessie main) or MySQL 5.6 (5.6.30-1~bpo8+1 from jessie-backports), the memory leak goes away and memory use stays constant over time.

            I see MySQL-python does not call mysql_close() on a failed connection which seems to resolve this behavior with MariaDB - so perhaps this is an incorrect API usage bug. However the MariaDB behavior does seem to differ from the MySQL (5.5.50, 5.6.30) behavior, so I am opening this issue.
            elenst Elena Stepanova made changes -
            Status Open [ 1 ] Confirmed [ 10101 ]
            elenst Elena Stepanova made changes -
            Component/s Scripts & Clients [ 11002 ]
            Fix Version/s 10.0 [ 16000 ]
            Fix Version/s 10.1 [ 16100 ]
            Affects Version/s 10.0 [ 16000 ]
            Affects Version/s 10.1 [ 16100 ]
            Affects Version/s 10.0.26 [ 22016 ]
            Affects Version/s 10.1.16 [ 22019 ]
            Assignee Oleksandr Byelkin [ sanja ]
            sanja Oleksandr Byelkin made changes -
            Status Confirmed [ 10101 ] In Progress [ 3 ]
            sanja Oleksandr Byelkin made changes -
            Status In Progress [ 3 ] Stalled [ 10000 ]
            sanja Oleksandr Byelkin made changes -
            Status Stalled [ 10000 ] In Progress [ 3 ]
            sanja Oleksandr Byelkin made changes -
            sanja Oleksandr Byelkin made changes -
            sanja Oleksandr Byelkin made changes -
            Fix Version/s 10.0.27 [ 22017 ]
            Fix Version/s 10.1.17 [ 22102 ]
            Fix Version/s 10.0 [ 16000 ]
            Fix Version/s 10.1 [ 16100 ]
            Resolution Fixed [ 1 ]
            Status In Progress [ 3 ] Closed [ 6 ]
            serg Sergei Golubchik made changes -
            Workflow MariaDB v3 [ 76518 ] MariaDB v4 [ 150679 ]

            People

              sanja Oleksandr Byelkin
              andrew.garner Andrew Garner
              Votes:
              0 Vote for this issue
              Watchers:
              4 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved:

                Git Integration

                  Error rendering 'com.xiplink.jira.git.jira_git_plugin:git-issue-webpanel'. Please contact your Jira administrators.