问题
can someone ELI5 what CONN_MAX_AGE does? I thought it worked like this:
1) Request #1 comes in, opens connection 1 to database
2) Request #1 uses connection 1 to do some work
3) Request #1 completes. Because CONN_MAX_AGE is non-zero (and the age has not been reached), the connection is left open.
4) Request #2 comes in, and Django re-uses connection #1 to the database.
But that doesn't seem to be happening. I have a page on my site that does an AJAX poll every 15 seconds. In my development environment, I see the number of open connections (select count(*) from pg_stat_activity), slowly grow, until eventually I get
OperationalError: FATAL: sorry, too many clients already
So I'm wondering where I've gone awry. Is CONN_MAX_AGE only used to keep connections open within a single HTTP request?
UPDATE:
Looking more carefully at the docs, I see this:
The development server creates a new thread for each request it handles, negating the effect of persistent connections. Don’t enable them during development.
Ah, so that seems to imply that a connection "belong to" a thread. (And the thread may open/close the connection, based on the value of CONN_MAX_AGE).
来源：https://stackoverflow.com/questions/41816570/how-does-conn-max-age-work-in-django