File Sync Locking Issue

Symptoms

Common error to all databases


java.lang.RuntimeException: Could not obtain file sync shared lock within 300000 millis

Database specific error

MySQL

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Explanation

The database connection has timed out which causes the sym_lock.csv file to be out of sync. As a result SymmetricDS assumes there is a lock in place and will not proceed.

Resolution

1.) Add the following property:

 db.validation.query=select 1

2.) Delete the sym_lock.csv

3.) Restart SymmetricDS