calculation for NUM_FIXED_LWLOCKS

Currently the calculation for NUM_FIXED_LWLOCKS is as
below, which I think has some problem:

/* Offsets for various chunks of preallocated lwlocks. */

#define BUFFER_MAPPING_LWLOCK_OFFSET NUM_INDIVIDUAL_LWLOCKS

#define LOCK_MANAGER_LWLOCK_OFFSET \

(BUFFER_MAPPING_LWLOCK_OFFSET + NUM_BUFFER_PARTITIONS)

#define PREDICATELOCK_MANAGER_LWLOCK_OFFSET \

(NUM_INDIVIDUAL_LWLOCKS + NUM_LOCK_PARTITIONS)

#define NUM_FIXED_LWLOCKS \

(PREDICATELOCK_MANAGER_LWLOCK_OFFSET + NUM_PREDICATELOCK_PARTITIONS)

In this PREDICATELOCK_MANAGER_LWLOCK_OFFSET

should consider NUM_BUFFER_PARTITIONS which means

it should be:

#define PREDICATELOCK_MANAGER_LWLOCK_OFFSET \

(*LOCK_MANAGER_LWLOCK_OFFSET* + NUM_LOCK_PARTITIONS)

If we don't consider buffer partitions in above calculation,
then the total shared memory allocated for fixed locks will
be wrong and can cause problems.

I have noticed this during my work on scaling shared
buffers where if I increase NUM_BUFFER_PARTITIONS,
it leads to hang for tpc-b test and as per my analysis
the reason is above calculation.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com