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
