jythonmultiprocessing

A module for Jython emulating (a small part of) CPython’s multiprocessing. With this, pygrametl can be made to use multiprocessing, but actually use threads when used from Jython (where there is no GIL).

class pygrametl.jythonmultiprocessing.JoinableQueue(maxsize=0)

Bases: Queue

close()

class pygrametl.jythonmultiprocessing.Process(group=None, target=None, name=None, args=(), kwargs=None, *, daemon=None)

Bases: Thread

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 a list or tuple of arguments 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.

property daemon

Return whether this thread is a daemon.

This method is deprecated, use the daemon attribute instead.

property name

Return a string used for identification purposes only.

This method is deprecated, use the name attribute instead.

pid = '<n/a>'

class pygrametl.jythonmultiprocessing.Queue(maxsize=0)

Bases: object

Create a queue object with a given maximum size.

If maxsize is <= 0, the queue size is infinite.

empty()

Return True if the queue is empty, False otherwise (not reliable!).

This method is likely to be removed at some point. Use qsize() == 0 as a direct substitute, but be aware that either approach risks a race condition where a queue can grow before the result of empty() or qsize() can be used.

To create code that needs to wait for all queued tasks to be completed, the preferred technique is to use the join() method.

full()

Return True if the queue is full, False otherwise (not reliable!).

This method is likely to be removed at some point. Use qsize() >= n as a direct substitute, but be aware that either approach risks a race condition where a queue can shrink before the result of full() or qsize() can be used.

get(block=True, timeout=None)

Remove and return an item from the queue.

If optional args ‘block’ is true and ‘timeout’ is None (the default), block if necessary until an item is available. If ‘timeout’ is a non-negative number, it blocks at most ‘timeout’ seconds and raises the Empty exception if no item was available within that time. Otherwise (‘block’ is false), return an item if one is immediately available, else raise the Empty exception (‘timeout’ is ignored in that case).

get_nowait()

Remove and return an item from the queue without blocking.

Only get an item if one is immediately available. Otherwise raise the Empty exception.

join()

Blocks until all items in the Queue have been gotten and processed.

The count of unfinished tasks goes up whenever an item is added to the queue. The count goes down whenever a consumer thread calls task_done() to indicate the item was retrieved and all work on it is complete.

When the count of unfinished tasks drops to zero, join() unblocks.

put(item, block=True, timeout=None)

Put an item into the queue.

If optional args ‘block’ is true and ‘timeout’ is None (the default), block if necessary until a free slot is available. If ‘timeout’ is a non-negative number, it blocks at most ‘timeout’ seconds and raises the Full exception if no free slot was available within that time. Otherwise (‘block’ is false), put an item on the queue if a free slot is immediately available, else raise the Full exception (‘timeout’ is ignored in that case).

put_nowait(item)

Put an item into the queue without blocking.

Only enqueue the item if a free slot is immediately available. Otherwise raise the Full exception.

qsize()

Return the approximate size of the queue (not reliable!).

task_done()

Indicate that a formerly enqueued task is complete.

Used by Queue consumer threads. For each get() used to fetch a task, a subsequent call to task_done() tells the queue that the processing on the task is complete.

If a join() is currently blocking, it will resume when all items have been processed (meaning that a task_done() call was received for every item that had been put() into the queue).

Raises a ValueError if called more times than there were items placed in the queue.

class pygrametl.jythonmultiprocessing.Value

Bases: object