Python queue module for concurrent parallel [2], queues

queue modules /queue module

1 Constants /Constants

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2 function /Function

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3 class /Class

3.1 Queue class

class Instantiation: Queue = queue. Queue(maxsize=0)

functions of the class : used to generate a first-in, first-out queue instance

Incoming Parameters : MaxSize

Maxsize:int type, maximum queue size, blocked when no space is specified, infinite queue when unspecified

return Parameters : Queue

Queue:instance type, generated first-in, first-out queue instance

3.1.1 put () Method

function Call : Queue.put (item, Block=true, Timeout=none)

function function : put item in the queue

Incoming Parameters : Item, block, timeout

Item:int/str/obj, etc. type, put into the queue of items

Block:bool type, set block, True is blocked, false throws an exception

Timeout:none/int type, set blocking time-out (s), None is blocked indefinitely

return Parameters : No

3.1.2 Get () Method

function Call : item = Queue.get (Block=true, Timeout=none)

function function : Remove the item from the queue

Incoming Parameters : block, timeout

Block:bool type, set block, True is blocked, false throws an exception

Timeout:none/int type, set blocking time-out (s), None is blocked indefinitely

return Parameters : Item

Item:int/str/obj types, items removed from the queue

3.1.3 put_nowait () Method

function Call : Queue.put_nowait (item)

function function : No wait to put item in queue, equivalent to put (item, False), failure throws full exception

Incoming Parameters : Item

Item:int/str/obj, etc. type, put into the queue of items

return Parameters : No

3.1.4 get_nowait () Method

function Call : item = queue.get_nowait ()

function function : No wait for the item to be fetched from the queue, equivalent to get (False), and failure throws an empty exception

Incoming Parameters : No

return Parameters : Item

Item:int/str/obj and other types, items removed from the queue

3.1.5 Task_done () Method

function Call : Queue.task_done ()

function function : used to indicate that a task has been completed, set the completion flag, often used for queue consumption threads, each get () function takes out an item, and can then set a task_done, when all queue tasks are marked complete, join will release blocking

Incoming Parameters : No

return Parameters : No

3.1.6 Join () Method

function Call : Queue.join ()

function function : used to block the current thread until all queues (including tasks before join into row and dequeue) are set with the Task_done flag before the join IS unblocked

Incoming Parameters : No

return Parameters : No

3.1.7 qsize () Method

function Call : size = queue.qsize ()

function function : Returns the size of the current queue (the value is not accurate, approximate, due to changes in other threads)

Incoming Parameters : No

return Parameters : Size

Siez:int type, number of item in queue

3.1.8 Empty () Method

function Call : status = Queue.empty ()

function function : Returns the status of the current queue, returns true for NULL, otherwise returns false, as with Qsize, returns an approximation, and if it is necessary to wait for all queues to end, the join () function is recommended

Incoming Parameters : No

return Parameters : Status

Status:bool type, true indicates that the current queue is empty

3.1.9 Full () Method

function Call : status = Queue.full ()

function function : Returns the status of the current queue, returns True if the queue is full, otherwise returns false, and returns an approximate value

Incoming Parameters : No

return Parameters : Status

Status:bool type, true indicates that the current queue is empty

3.2 Lifoqueue class

class Instantiation: Queue = queue. Lifoqueue(maxsize=0)

functions of the class : used to generate a back-in, first-out queue instance

Incoming Parameters : MaxSize

Maxsize:int type, maximum queue size, blocked when no space is specified, infinite queue when unspecified

return Parameters : Queue

Queue:instance type, generated after-first-out queue instance

Note:

For the Lifoqueue class, the base class is the queue, where the queue's _init, _qsize, _put, _get functions are redefined in the source code so that they differ in the order in which the queues are processed (the essence is _get () when the item is fetched to the queue list) function uses either the Popleft function or the pop function, and the function of its parent class can be inherited.

3.3 Priorityqueue class

class Instantiation: Queue = queue. Priorityqueue(maxsize=0)

functions of the class : used to generate a priority queue instance with the smallest optimal pull-out

Incoming Parameters : MaxSize

Maxsize:int type, maximum queue size, blocked when no space is specified, infinite queue when unspecified

return Parameters : Queue

Queue:instance type, generated priority queue instance

Note:

For the Priorityqueue class, the base class is also the queue, which also redefined the queue's _init, _qsize, _put, _get functions in the source code, making it different in the queue's processing order (the essence is _get () when the item is fetched to the queue list) The Heappop function is used, and the Heappush function is used when it is placed, and the parent function can also be used for inheritance.

3.4 Empty Exception Class

class Instantiation: No

functions of the class : for exceptions thrown when the queue is empty and the get* () method is called

Incoming Parameters : No

return Parameters : No

3.5 Full Exception Class

class Instantiation: No

functions of the class : for exceptions thrown when the queue is full and the put* () method is called

Incoming Parameters : No

return Parameters : No

Python queue module for concurrent parallel [2], queues