BIND 10 #1356: Simultaneous transfers fail with Sqlite3 data source

[BIND 10 Development]

#1356: Simultaneous transfers fail with Sqlite3 data source
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            Reporter:  vorner  |                        Owner:
                Type:  defect  |                       Status:  new
            Priority:  minor   |                    Milestone:  New Tasks
           Component:  xfrin   |                     Keywords:
           Sensitive:  0       |              Defect Severity:  N/A
         Sub-Project:  DNS     |  Feature Depending on Ticket:
Estimated Difficulty:  0       |          Add Hours to Ticket:  0
         Total Hours:  0       |                    Internal?:  0
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 When an attempt is made to perform two simultaneous transfers in, the
 second one crashes with this:

 {{{
 Exception in thread Thread-33:
 Traceback (most recent call last):
   File "/usr/lib64/python3.2/threading.py", line 740, in _bootstrap_inner
       self.run()
         File "/usr/lib64/python3.2/threading.py", line 693, in run
             self._target(*self._args, **self._kwargs)
               File
 "/home/vorner/testing/bind10/libexec/bind10-devel/b10-xfrin", line 819, in
 process_xfrin
                   datasrc_client = DataSourceClient(datasrc_type,
 datasrc_config)
                   isc.datasrc.Error: Failed to create DataSourceClient of
 type sqlite3:Unknown uncaught exception from sqlite3 createInstance: Error
 creating sqlite3 datasource: Unable to query version: database is locked
 }}}

 This is fundamental problem of Sqlite3, as it has table-wise locking. But
 we should probably set the default max-transfers value to 1, as sqlite3 is
 our only backend right now.

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Ticket URL: <http://bind10.isc.org/ticket/1356>
BIND 10 Development <http://bind10.isc.org>
BIND 10 Development