.. not a general timeout.
Now, if a thread checks out a connection then dies, we can immediately
recover that connection and re-use it.
This should alleviate the pool exhaustion discussed in #12867. More
importantly, it entirely avoids the potential issues of the reaper
attempting to check whether connections are still active: as long as the
owning thread is alive, the connection is its business alone.
As a no-op reap is now trivial (only entails checking a thread status
per connection), we can also perform one in-line any time we decide to
sleep for a connection.
Follow-Up to https://github.com/rails/rails/pull/14348
Ensure that SQLCounter.clear_log is called after each test.
This is a step to prevent side effects when running tests. This will allow us to run them in random order.
An AR ConnectionSpec `wait_timeout` is pre-patch used for three
different things:
* mysql2 uses it for MySQL's own wait_timeout (how long MySQL
should allow an idle connection before closing it), and
defaults to 2592000 seconds.
* ConnectionPool uses it for "number of seconds to block and
wait for a connection before giving up and raising a timeout error",
default 5 seconds.
* ConnectionPool uses it for the Reaper, for deciding if a 'dead'
connection can be reaped. Default 5 seconds.
Previously, if you want to change these from defaults, you need
to change them all together. This is problematic _especially_
for the mysql2/ConnectionPool conflict, you will generally _not_
want them to be the same, as evidenced by their wildly different
defaults. This has caused real problems for people #6441#2894
But as long as we're changing this, forcing renaming the
ConnectionPool key to be more specific, it made sense
to seperate the two ConnectionPool uses too -- these two
types of ConnectionPool timeouts ought to be able to be
changed independently, you won't neccesarily want them
to be the same, even though the defaults are (currently)
the same.