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Call catching - Cromwell exhausts all connection to mysqld

Anyone experienced leaky Cromwell when call-catching with mysql table? Even after extending max_connections to 5000 it complains, i.e. I can only run a single Cromwell run at a time.

mysql --socket=../socket -u root
ERROR 1040 (HY000): Too many connections

Any suggestions?


  • RuchiRuchi Member, Broadie, Moderator, Dev admin

    Hey @dplichta,

    Just so I understand better -- are you trying to use the same mysql DB between multiple Cromwell instances?

  • dplichtadplichta Member

    Hi @Ruchi,

    Yes, in the early few days of me playing with cromwell+wdl I did exactly that, until for this and other reasons (cromwell exhausing max. number of processes allowed in the system) I switched to cromwell server.

    Thanks for getting back on this,


  • RuchiRuchi Member, Broadie, Moderator, Dev admin

    Hey Damian,

    You might want to try setting the key maxConnection to something to restrict Cromwell from taking up too many connections:

    database {
      # mysql example
      profile = "slick.jdbc.MySQLProfile$"
      db {
        driver = "com.mysql.jdbc.Driver"
        url ="jdbc:mysql://mysql...."
        user = "..."
        password = "..."
        maxConnections = "<number-of-your-choice>"
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