On Thu, 2024-07-25 at 10:58 +0000, Christian Schröder wrote: > The current error messages are similar to what we have seen before: > > <2024-07-25 12:27:38 CEST - > LOG: could not fork autovacuum worker process: Cannot allocate memory > <2024-07-25 12:27:38 CEST - mailprocessor> ERROR: could not resize shared memory segment "/PostgreSQL.1226901392" to 189280 bytes: No space left on device > > As far as I understand, it does not make much sense to look into SysV shared > memory (which is what ipcs does). Indeed, there is only the same small shared > memory segment as we have seen back then: > > [...] > > Francisco and Tom both pointed at Posix shared memory instead; however, this > also does not seem to be used a lot: > > # df -h /dev/shm > Filesystem Size Used Avail Use% Mounted on > tmpfs 7.8G 6.6M 7.8G 1% /dev/shm > > We also still see a lot of available memory: > > # free -m > total used free shared buff/cache available > Mem: 15882 6966 191 2109 8725 6477 > Swap: 1999 271 1728 > > Again, exactly the same situation as before. > > Tom suggested that we hit some kernel limits, but I could not find any related > kernel setting. The only limit I am aware of is the size of the /dev/shm filesystem > itself. This could be changed, but the default value of 8 GB (which is half of > the machine's memory) seems to be enough (given that it is not even used). > > Is there anything else I can analyze? Sorry again for reviving this old thread. It could be dynamic shared memory segments created temporarily during parallel query execution. Try setting "max_parallel_workers_per_gather = 0", that should make that problem disappear. Yours, Laurenz Albe
