locked database prevents from build jobs being started

[tpokorra]

--- Logging error ---
Traceback (most recent call last):
  File "/usr/share/lightbuildserver/web/lbs.py", line 86, in processbuildqueue
    self.LBS.ProcessBuildQueue()
  File "/usr/share/lightbuildserver/web/../lib/LightBuildServer.py", line 455, in ProcessBuildQueue
    self.attemptToFindBuildMachine(con, row)
  File "/usr/share/lightbuildserver/web/../lib/LightBuildServer.py", line 435, in attemptToFindBuildMachine
    buildmachine=self.GetAvailableBuildMachine(con,username,projectname,packagename,branchname,lxcdistro,lxcrelease,lxcarch,AvoidDocker,AvoidLXC)
  File "/usr/share/lightbuildserver/web/../lib/LightBuildServer.py", line 155, in GetAvailableBuildMachine
    cursor.execute(stmt)
sqlite3.OperationalError: database is locked

Later (might be unrelated):

stopping machine build02.lbs.solidcharity.com because of hanging build
ReleaseMachine build02.lbs.solidcharity.com

[tpokorra]

the question is why do we need an increased timeout? which query is blocking the database for so long?

[tpokorra]

is it the logs writing quite often to the database?

should we offer an alternative db access method for Mysql? modify ConnectDatabase

need to convert existing sqlite database to mysql? http://stackoverflow.com/a/1067365/1632368

or first try to work with a single db connection, rather than creating a new connection for each method? Problem both Logger and Lightbuildserver.py need to have a connection

[tpokorra]

Fedora23, mysql:

dnf install python3-mysql mariadb-server
systemctl enable mariadb
systemctl start mariadb
mysql
    CREATE DATABASE lbs  DEFAULT CHARACTER SET utf8   DEFAULT COLLATE utf8_general_ci;
    GRANT ALL ON lbs.* TO lbs@localhost IDENTIFIED BY 'secret';
# open lbs in webbrowser, that should create the database
sqlite3 /var/lib/lightbuildserver/db/lightbuildserver.db .dump > my.sql
#  only need the insert statements for table build
# :%s/"build"/`build`(id,status,username,projectname,packagename,branchname,distro,`release`,arch,dependsOnOtherProjects,buildmachine,started,finished, buildsuccess, buildnumber, hanging, avoidlxc,avoiddocker)/g
# instead of sequences: ALTER TABLE build AUTO_INCREMENT=5000;