Read path: the leased pool replaces the thread-local cache. Pooled
connections record Database._conn_generation when opened; a stale one is
discarded on checkout or return, and _invalidate_connections() (called
by the SchemaWatcher on a replaced/deleted file) closes that database's
idle connections at once. Leased ones are only ever closed by their own
thread on release.
Write path: the idle-exit write thread keeps its lock protocol; its
connection lives in a _WriteConnection holder that is reopened when the
generation moves, before the next task. Post-write schema_version check
and _after_write catalog await are kept for every write API in both
modes. Non-threaded write connections are reopened on a generation change
and never cached half-prepared.
Deleted files: write connections use mode=rw once Datasette has seen the
file exist (_file_seen), so a deleted file is never silently recreated,
while a database added before its file exists is still created by its
first write.
Settings: max_open_connections (clamped to >= 4 x num_sql_threads),
connection_idle_timeout_ms (30000, read connections and write threads),
schema_watch_interval_ms, default_schema_watch (external|owned). The
spike-only knobs (connection_idle_timeout, connection_pool_wait_ms,
pool_read_connections, write_thread_idle_timeout_ms) are gone, along with
the pool's wait/disable code paths. The reaper falls back to checkout-time
reaping where threads cannot be started (Pyodide).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EwkLo2rJWidpkDVT3HkvNv
New setting write_thread_idle_timeout_ms (default 30000, 0 disables).
A database's write thread now waits on queue.get(timeout=...) and, when
it times out, takes _write_thread_lock, re-checks that the queue is
empty, deregisters itself and closes its write connection. Producers
enqueue and check/start the thread under the same lock, so a task can
never be left in the queue with no thread to run it.
Also: close() refuses new tasks under the lock and joins retiring
threads; a failed connect is retried by the next write once the queue
drains; memory databases never idle out; a thread that dies from a
BaseException deregisters (and restarts if tasks are waiting); the
thread is registered only after start() succeeds.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EwkLo2rJWidpkDVT3HkvNv
