Create a lock before acquiring.

Author: lohedges

src/somd2/runner/_runner.py

@@ -938,6 +938,9 @@ def generate_lam_vals(lambda_base, increment=0.001):
             # Calculate the speed in nanoseconds per day.
             speed = time.to("ns") / days
 
+            # Create the lock.
+            lock = _FileLock(self._lock_file)
+
             # Acquire the file lock to ensure that the checkpoint files are
             # in a consistent state if read by another process.
             with lock.acquire(timeout=self._config.timeout.to("seconds")):