navigate.model.concurrency.concurrency_tools.ResultThread
- class navigate.model.concurrency.concurrency_tools.ResultThread(group=None, target=None, name=None, args=(), kwargs=None)
Bases:
Threadthreading.Thread with all the simple features we wish it had.
We added a ‘get_result’ method that returns values/raises exceptions.
We changed the return value of ‘start’ from ‘None’ to ‘self’ – just to trivially save us a line of code when launching threads.
- def f(a):
‘’’ A function that does something… ‘’’ return a.sum()
## ## Getting Results: ## a = np.ones((2,), dtype=’uint8’)
# Our problem: th = threading.Thread(target=f, args=(a,)) th.start() th.join() # We can’t access the result of f(a) without redefining f!
# Our solution: res_th = ResultThread(target=f, args=(a,)).start() res = res_th.get_result() # returns f(a) assert res == 2
## ## Error handling ## a = 1
# Our problem: th = threading.Thread(target=f, args=(a,)) th.start() th.join() # f(a) raised an unhandled exception. Our parent thread has no idea!
# Our solution: res_th = ResultThread(target=f, args=(a,)).start() try:
res = res_th.get_result()
- except AttributeError:
print(“AttributeError was raised in thread!”)
- else:
- raise AssertionError(
‘We expected an AttributeError to be raised on join!’)
# Unhandled exceptions raised during evaluation of ‘f’ are reraised in # the parent thread when you call ‘get_result’. # Tracebacks may print to STDERR when the exception occurs in # the child thread, but don’t affect the parent thread (yet).
``` NOTE: This module modifies threading.excepthook. You can’t just copy/paste this class definition and expect it to work.
- __init__(group=None, target=None, name=None, args=(), kwargs=None)
This constructor should always be called with keyword arguments. Arguments are:
group should be None; reserved for future extension when a ThreadGroup class is implemented.
target is the callable object to be invoked by the run() method. Defaults to None, meaning nothing is called.
name is the thread name. By default, a unique name is constructed of the form “Thread-N” where N is a small decimal number.
args is the argument tuple for the target invocation. Defaults to ().
kwargs is a dictionary of keyword arguments for the target invocation. Defaults to {}.
If a subclass overrides the constructor, it must make sure to invoke the base class constructor (Thread.__init__()) before doing anything else to the thread.
Methods
__init__([group, target, name, args, kwargs])This constructor should always be called with keyword arguments.
getName()Return a string used for identification purposes only.
get_result([timeout])Either returns a value or raises an exception.
isDaemon()Return whether this thread is a daemon.
is_alive()Return whether the thread is alive.
join([timeout])Wait until the thread terminates.
run()Method representing the thread's activity.
setDaemon(daemonic)Set whether this thread is a daemon.
setName(name)Set the name string for this thread.
start()Start the thread's activity.
Attributes
A boolean value indicating whether this thread is a daemon thread.
Thread identifier of this thread or None if it has not been started.
A string used for identification purposes only.
Native integral thread ID of this thread, or None if it has not been started.
- getName()
Return a string used for identification purposes only.
This method is deprecated, use the name attribute instead.
- get_result(timeout=None)
Either returns a value or raises an exception.
Optionally accepts a timeout in seconds. If thread has not returned after timeout seconds, raises a TimeoutError.
- isDaemon()
Return whether this thread is a daemon.
This method is deprecated, use the daemon attribute instead.
- is_alive()
Return whether the thread is alive.
This method returns True just before the run() method starts until just after the run() method terminates. See also the module function enumerate().
- join(timeout=None)
Wait until the thread terminates.
This blocks the calling thread until the thread whose join() method is called terminates – either normally or through an unhandled exception or until the optional timeout occurs.
When the timeout argument is present and not None, it should be a floating point number specifying a timeout for the operation in seconds (or fractions thereof). As join() always returns None, you must call is_alive() after join() to decide whether a timeout happened – if the thread is still alive, the join() call timed out.
When the timeout argument is not present or None, the operation will block until the thread terminates.
A thread can be join()ed many times.
join() raises a RuntimeError if an attempt is made to join the current thread as that would cause a deadlock. It is also an error to join() a thread before it has been started and attempts to do so raises the same exception.
- run()
Method representing the thread’s activity.
You may override this method in a subclass. The standard run() method invokes the callable object passed to the object’s constructor as the target argument, if any, with sequential and keyword arguments taken from the args and kwargs arguments, respectively.
- setDaemon(daemonic)
Set whether this thread is a daemon.
This method is deprecated, use the .daemon property instead.
- setName(name)
Set the name string for this thread.
This method is deprecated, use the name attribute instead.
- start()
Start the thread’s activity.
It must be called at most once per thread object. It arranges for the object’s run() method to be invoked in a separate thread of control.
This method will raise a RuntimeError if called more than once on the same thread object.
- property daemon
A boolean value indicating whether this thread is a daemon thread.
This must be set before start() is called, otherwise RuntimeError is raised. Its initial value is inherited from the creating thread; the main thread is not a daemon thread and therefore all threads created in the main thread default to daemon = False.
The entire Python program exits when only daemon threads are left.
- property ident
Thread identifier of this thread or None if it has not been started.
This is a nonzero integer. See the get_ident() function. Thread identifiers may be recycled when a thread exits and another thread is created. The identifier is available even after the thread has exited.
- property name
A string used for identification purposes only.
It has no semantics. Multiple threads may be given the same name. The initial name is set by the constructor.
- property native_id
Native integral thread ID of this thread, or None if it has not been started.
This is a non-negative integer. See the get_native_id() function. This represents the Thread ID as reported by the kernel.