Shared Memory files getting deleted some time (~15 hours) in Postgres 11
2019-07-09 08:46:41 CDT [] [6723]: [1-1] user=,db=,e=58P01 ERROR: could not open shared memory segment "/PostgreSQL.291691635": No such file or directory
2019-07-09 08:46:41 CDT [] [6722]: [1-1] user=,db=,e=58P01 ERROR: could not open shared memory segment "/PostgreSQL.291691635": No such file or directory
2019-07-09 08:46:41 CDT [10.40.0.204(60550)] [13880]: [1-1] user=user_name,db=db_name,e=58P01 ERROR: could not open shared memory segment "/PostgreSQL.291691635": No such file or directory
2019-07-09 08:46:41 CDT [10.40.0.204(60550)] [13880]: [2-1] user=user_name,db=db_name,e=58P01 CONTEXT: parallel worker
2019-07-09 08:46:41 CDT [10.40.0.204(60550)] [13880]: [3-1] user=user_name,db=db_name,e=58P01 STATEMENT: WITH overall_reviewed AS (SQL Query)
GCP VM Config
CPU: 4
RAM: 16 GB
OS: Ubuntu 18.04.1 LTS
kernel shared memory setting shared
kernel.shmmax=8589934592
kernel.shmall=2097152
postgresql.config
max_connections = 500
shared_buffers = 4GB
effective_cache_size = 12GB
maintenance_work_mem = 1GB
checkpoint_completion_target = 0.7
wal_buffers = 16MB
default_statistics_target = 100
random_page_cost = 1.1
effective_io_concurrency = 200
work_mem = 4194kB
min_wal_size = 1GB
max_wal_size = 2GB
max_worker_processes = 4
max_parallel_workers_per_gather = 2
max_parallel_workers = 4
During startup: no errors/warnings
After ~15 hours some of the shared memory files is getting deleted, I'm doubting is there any other process deleting files in "/dev/shm" ?
Not sure what is the root cause
making dynamic_shared_memory_type = none in postgresql.conf did solve the issue.