Thomas Munro schrieb am 26.10.2018 um 22:13: >>> I typically configure "shared_buffers = 4096MB" on my 16GB system as >>> sometimes when testing, it pays off to have a bigger cache. >>> >>> With Postgres 10 and earlier, the Postgres process(es) would only >>> allocate that memory from the operating system when needed. >>> So right after startup, it would only consume several hundred MB, not >>> the entire 4GB >>> >>> However with Postgres 11 I noticed that it immediately grabs the >>> complete memory configured for shared_buffers during startup. >>> >>> It's not really a big deal, but I wonder if that is an intentional >>> change or a result from something else? >>> >>> >>> Do you have pg_prewarm in shared_preload_libraries? >> >> No. The only shared libraries are those for pg_stat_statemens > > Does your user have "Lock Pages in Memory" privilege? One thing that > is new in 11 is huge AKA large page support, and the default is > huge_pages=try. Not a Windows person myself but I believe that should > succeed if you have that privilege and enough contiguous chunks of > physical memory are available. If you set huge_pages=off does it > revert to the old behaviour?
Turns out this was an "optimization" in Windows 10, and completely unrelated to Postgres. Windows 10 has a feature called "Fast Boot" (or something along the lines). When that is activated (which it is by default), a proper shutdown of the system does not seem to really shut it down. This is especially noteworthy with services: they don't get a shutdown event (which e.g. means even a service marked as "manual start", will still be running after a reboot if it did before) In case of Postgres this is visible e.g. in the logfile, because there will no shutdown or startup messages. So when I booted my laptop, Postgres continued where it was before the reboot - and the memory usage was caused caused by myself generating test data using generate_series() but I expected a "clean" state after the reboot. When manually restarting the service everything works as expected. Sorry for the noise.
