The global lock¶
Python-LLFUSE uses a global lock to synchronize concurrent requests. Since the GIL already enforces that Python threads do not run concurrently, this does not result in any additional performance penalties. However, the use of an explicit lock allows direct control over which Python thread is running at a given time.
Request handlers will always be called with the global lock acquired. However, they may release the global lock for potentially time consuming operations (like network or disk I/O), or to give other threads a chance to run during longer computations.
Non-request handling threads may acquire the global lock to ensure that the execution of a particular code block will not be interrupted by any request handlers.
Obviously, any method that directly or indirectly releases the global lock must be prepared to be called again while it has released the lock. In addition, it (and all its callers) must not hold any prior locks, since this may lead to deadlocks when re-acquiring the global lock. For this reason it is crucial that every method that directly or indirectly releases the lock is explicitly marked as such.
The global lock is controlled with the lock
and lock_released
attributes of the llfuse
module:
- llfuse.lock_released¶
Controls the global lock. This object can be used as a context manager for the
with
statement to execute a block of code with the global lock released.
- llfuse.lock¶
Controls the global lock. This object can be used as a context manager for the
with
statement to execute a block of code with the global lock acquired.Note that this object resembles a
threading.Lock
instance but is an instance of thellfuse.Lock
class which is quite different fromthreading.Lock
.
The lock
object has the following methods:
- class llfuse.Lock¶