Hello, all:

 

Derby is used in my application in the in-memory only mode. For a long time Derby’s lock logic caused no worries, but recently some use cases failed with lock timeouts. Thus I’m looking for guidance on best practices for handling locks in Derby. A use-case which may cause timeouts to obtain a lock: one thread is executing an SQL statement which accesses two (or more) in-memory tables. Those two tables are being modified by  other threads at random times. So, situations in which the SQL is executed for a long time and the other threads are frequently updating the tables may cause lock timeouts.

 

Besides best practices to avoid timeouts and deadlocks, I would like to ask the following questions:

1)      What’s the default length of lock timeouts?

2)      Does my app need another layer of synchronization mechanism/locks to avoid attempts to update in-memory tables or execute SQLs against them?

3)      Can my application utilize Derby’s locks through some API – to query their state or to use them in making a decision of whether to batch updates or to execute them, to wait or execute the SQLs?

 

Your help would be greatly appreciated,

 

Pavel.

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