- Multiprocessing Pool Worker PIDs in Python
- Need Worker Process PID
- How to Get Worker Process PID
- How to Get Worker PID Within Worker
- How to Get the Process PID in Python
- Need To Get a Process PID
- What is a PID
- How to Get a Process PID
- PID via Process Instance
- Get Multiprocessing Pool Worker PID in Python
- Need PID of Worker Processes
- What is a PID
- How to Get Worker PID
- How to Get Process PID
Multiprocessing Pool Worker PIDs in Python
You can get the PID of workers in the process pool using os.getpid() from within the task or multiprocessing.active_children() from the parent process.
In this tutorial you will discover how to get the PID of process pool child worker processes in Python.
Need Worker Process PID
The multiprocessing.pool.Pool in Python provides a pool of reusable processes for executing ad hoc tasks.
A process pool can be configured when it is created, which will prepare the child workers.
A process pool object which controls a pool of worker processes to which jobs can be submitted. It supports asynchronous results with timeouts and callbacks and has a parallel map implementation.
— multiprocessing — Process-based parallelism
We can issue one-off tasks to the process pool using functions such as apply() or we can apply the same function to an iterable of items using functions such as map(). Results for issued tasks can then be retrieved synchronously, or we can retrieve the result of tasks later by using asynchronous versions of the functions such as apply_async() and map_async().
Each Python process is created and managed by the underlying operating system.
As such, each process is allocated a unique process identifier, referred to as a PID.
How can we get the PID for worker processes in the process pool?
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How to Get Worker Process PID
We can get the worker process PIDs in two ways, they are:
- From within the worker process itself.
- From the parent process that created the process pool.
Let’s take a closer look at each approach.
How to Get Worker PID Within Worker
We can get the PID of worker processes from within the workers themselves.
The task that is executed by a worker process can get its own PID.
How to Get the Process PID in Python
You can get the process pid via the multiprocessing.Process.pid attribute or via the os.getpid() and os.getppid() functions.
In this tutorial you will discover how to get the process pid in Python.
Need To Get a Process PID
A process is a running instance of a computer program.
Every Python program is executed in a Process, which is a new instance of the Python interpreter. This process has the name MainProcess and has one thread used to execute the program instructions called the MainThread. Both processes and threads are created and managed by the underlying operating system.
Sometimes we may need to create new child processes in our program in order to execute code concurrently.
Python provides the ability to create and manage new processes via the multiprocessing.Process class.
You can learn more about multiprocessing in the tutorial:
In multiprocessing, we may need to get the process identifier or PID of a process.
- We may need the pid of the current process.
- We may need the pid of a child process.
- We may need the pid of the parent process.
How can we get the pid of a process in Python?
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What is a PID
A process identifier is a unique number assigned to a process by the underlying operating system.
Each time a process is started, it is assigned a unique positive integer identifier and the identifier may be different each time the process is started.
The pid uniquely identifies one process among all active processes running on the system, managed by the operating system.
As such, the pid can be used to interact with a process, e.g. to send a signal to the process to interrupt or kill a process.
Confused by the multiprocessing module API?
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How to Get a Process PID
We can get the pid from the multiprocessing.Process instance or via os module functions such as os.getpid() and os.getppid().
Let’s take a closer look at each approach in turn.
PID via Process Instance
We can get the pid of a process via its multiprocessing.Process instance.
When we create a child process, we may hang on to the process instance.
Alternatively, we may get the process instance for the parent process via the multiprocessing.parent_process() function or for child process via the multiprocessing.active_children() function.
We may also get the process instance for the current process via the multiprocessing.current_process() function.
Get Multiprocessing Pool Worker PID in Python
You can get the PID of a worker process by calling the os.getpid() function when initializing the worker process or from within the target task function executed by a worker process.
In this tutorial you will discover how to get the PID of worker processes in the Python process pool.
Need PID of Worker Processes
The multiprocessing.pool.Pool in Python provides a pool of reusable processes for executing ad hoc tasks.
A process pool can be configured when it is created, which will prepare the child workers.
A process pool object which controls a pool of worker processes to which jobs can be submitted. It supports asynchronous results with timeouts and callbacks and has a parallel map implementation.
— multiprocessing — Process-based parallelism
We can issue one-off tasks to the process pool using functions such as apply() or we can apply the same function to an iterable of items using functions such as map().
Results for issued tasks can then be retrieved synchronously, or we can retrieve the result of tasks later by using asynchronous versions of the functions such as apply_async() and map_async().
When using the process pool, we may need the process identifiers (PIDs) of the worker processes.
This may be for many reasons, such as:
- To uniquely identify the worker in the application.
- To include the PID in logging.
- To debug which worker is completing which task.
How can we get the child worker process PIDs in Python?
Run your loops using all CPUs, download my FREE book to learn how.
What is a PID
PID is an acronym for Process ID or Process identifier.
A process identifier is a unique number assigned to a process by the underlying operating system.
Each time a process is started, it is assigned a unique positive integer identifier and the identifier may be different each time the process is started.
The pid uniquely identifies one process among all active processes running on the system, managed by the operating system.
As such, the pid can be used to interact with a process, e.g. to send a signal to the process to interrupt or kill a process.
Confused by the Pool class API?
Download my FREE PDF cheat sheet
How to Get Worker PID
When working with a process pool, there are two situations where we may want to get the PID:
- Get the PID for each worker process in the process pool.
- Get the PID for the worker completing a given task.
Let’s take a closer look at each approach in turn.
Before we get the PID of worker processes, let’s take a brief look at how to get a process PID.
How to Get Process PID
There are two general ways to get the PID for a process, they are:
- multiprocessing.Process.pid attribute.
- os.getpid() function.
We may also get the process instance for the current process via the multiprocessing.current_process() function.