chore(persistence): drop redundant busy_timeout PRAGMA

Python's sqlite3 driver defaults to a 5-second busy timeout via the
``timeout`` kwarg of ``sqlite3.connect``, and aiosqlite + SQLAlchemy's
aiosqlite dialect inherit that default. Setting ``PRAGMA busy_timeout=5000``
explicitly was a no-op — verified by reading back the PRAGMA on a fresh
connection (it already reports 5000ms without our PRAGMA).

Concurrent stress test (50 checkpoint writes + 20 event batches + 50
thread_meta updates on the same deerflow.db) still completes with zero
errors and 200/200 rows after removing the explicit PRAGMA.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
rayhpeng
2026-04-11 11:25:14 +08:00
parent 10cc651578
commit 4810898cfa
2 changed files with 8 additions and 5 deletions
@@ -7,10 +7,9 @@ configures one backend; the system handles physical separation details.
SQLite mode: checkpointer and app share a single .db file
({sqlite_dir}/deerflow.db) with WAL journal mode enabled on every
connection. WAL allows concurrent readers and a single writer without
blocking, making a unified file safe for both workloads. The
``busy_timeout`` PRAGMA (set in ``engine.py``) ensures writers wait
for each other instead of failing immediately when they contend for
the write lock.
blocking, making a unified file safe for both workloads. Writers
that contend for the lock wait via the default 5-second sqlite3
busy timeout rather than failing immediately.
Postgres mode: both use the same database URL but maintain independent
connection pools with different lifecycles.