/* 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.
