Re: [HACKERS] lock deadlocks

> I have just encountered some applications that really need
> transactions and so have been perusing the transaction statements and
> the lock man page.  Thinking of the possibility of deadlocks if two
> processes try to acquire locks in opposite order suggested a solution.
> 
> Couldn't the parser syntax be expanded to
> 
>      LOCK [TABLE] table1 [, table2 [, table3 [...]]]
> 
> in which case locks on the entire group of tables could be obtained
> atomically.  If one fails, the process should release locks on all the
> rest, wait a bit, and retry.  This should prevent infinite deadlocks
> since all locks (not just the most recent one of several independent
> locks) would be released at some point, allowing other processes to
> assert theirs.

You give a nice extension of the LOCK statement, that is quite valid,
_and_ can not be simulated with multiple lock statements.

Complex kernel locking systems, mostly multi-cpu kernels, have to do
similar things.  You want an 'all or nothing' lock statement.  I will
add this to the TODO list.

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