Python 3.12 introduces subinterpreters for true parallelism

Beyond the GIL: True Parallelism in Python with Subinterpreters (PEP 554) We're all familiar with the classic challenge of parallelizing CPU-bound workloads in Python. We've navigated through threads limited by the GIL, processes with serialization overhead, and asynciofor IO-bound tasks. But what if the next evolutionary step is already here, just waiting to be adopted? I'm talking about subinterpreters—isolated interpreters within a single process, introduced in Python 3.12. The per-interpreter GIL model means each subinterpreter has its own private GIL. This allows multiple threads to actually run simultaneously on different CPU cores, executing Python code, all within the same process and sharing some memory (e.g., for immutable objects). This isn't multiprocessing with its heavy pickle and memory separation via queues, nor is it GIL-bound multithreading. It's a fundamentally different concurrency model. So, why aren't we all rewriting our applications to use subinterpreters? The challenge lies in the fact that calling Py_NewInterpreter() from C is just the beginning. The core issue is state. Many popular C extensions, like numpy, are not yet "isolated" ready, as they rely on global static state. Until we have a robust and safe mechanism for data sharing between these isolated worlds (hint: it will likely resemble an actor model more than classic shared memory), this technology will remain niche. However, it represents a critical frontier for pushing Python's performance boundaries, demanding architectural decisions that go far beyond choosing between asyncio and multiprocessing. #Python #GIL #HighPerformanceComputing #HPC #PythonAdvanced #SoftwareArchitecture #Concurrency #Subinterpreters

  • No alternative text description for this image

To view or add a comment, sign in

Explore content categories