Øystein Kolsrud schrieb am 17.09.2020 um 11:19:
All settings typically referred to (like "work_mem" and "temp_buffers") are at default settings, and I have a very hard time seeing how those settings could add up to memory in the magnitude of 200MB. The "max_connections" settings is quite high (>1000), but there are nowhere near that many connections active in the system. The only way I have been able to trigger growth of processes in my tests is to extract large amounts of data, but when I do that, it is always the "shared working set" that grows. "private working set" remains stable at around 5 MB.
It's not clear to me how many open (vs. "active") connections you have. An "active" connection is one that is currently _running_ a statement, an "open" is one that is "idle", i.e. not doing anything. To my knowledge, a single backend process (=connection) will not release the memory it once allocated. The only way to free that memory is to physically close the connection. So if all your > 1000 connections are currently idle/open (but not "active"), they will still consume the memory they have allocated _when_ they where active. With that high number of connections it isn't really surprising that you run out of memory at one point or another then.
