Nuitka Release 0.5.22

This is to inform you about the new stable release of Nuitka. It is the extremely compatible Python compiler. Please see the page "What is Nuitka?" for an overview.

This release is mostly an intermediate release on the way to the large goal of having per module compilation that is cachable and requires far less memory for large programs. This is currently in progress, but required many changes that are in this release, more will be needed.

It also contains a bunch of bug fixes and enhancements that are worth to be released, and the next changes are going to be more invasive.

Bug Fixes

  • Compatibility: Classes with decorated __new__ functions could miss out on the staticmethod decorator that is implicit. It's now applied always, unless of course it's already done manually. This corrects an issue found with Pandas. Fixed in 0.5.22.1 already.
  • Standalone: For at least Python 3.4 or higher, it could happen that the locale needed was not importable. Fixed in 0.5.22.1 already.
  • Compatibility: Do not falsely assume that not expressions cannot raise on boolean expressions, since those arguments might raise during creation. This could lead to wrong optimization. Fixed in 0.5.22.2 already.
  • Standalone: Do not include system specific C libraries in the distribution created. This would lead to problems for some configurations on Linux in cases the glibc is no longer compatible with newer oder older kernels. Fixed in 0.5.22.2 already.
  • The --recurse-directory option didn't check with decision mechanisms for module inclusion, making it impossible to avoid some things.

Optimization

  • Introduced specialized constant classes for empty dictionaries and other special constants, e.g. "True" and "False", so that they can have more hard coded properties and save memory by sharing constant values.
  • The "technical" sharing of a variable is only consider for variables that had some sharing going in the first place, speeing things up quite a bit for that still critical check.
  • Memory savings coming from enhanced trace storage are already visible at about 1%. That is not as much as the reloading will mean, but still helpful to use less overall.

Cleanups

  • The global variable registry was removed. It was in the way of unloading and reloading modules easily. Instead variables are now attached to their owner and referenced by other users. When they are released, these variables are released.
  • Global variable traces were removed. Instead each variable has a list of the traces attached to it. For non-shared variables, this allows to sooner tell attributes of those variables, allowing for sooner optimization of them.
  • No longer trace all initial users of a variable, just merely if there were such and if it constitutes sharing syntactically too. Not only does this save memory, it avoids useless references of the variable to functions that stop using it due to optimization.
  • Create constant nodes via a factory function to avoid non-special instances where variants exist that would be faster to use.
  • Moved the C string functions to a proper nuitka.utils.CStrings package as we use it for better code names of functions and modules.
  • Made functions and explicit child node of modules, which makes their use more generic, esp. for re-loading modules.
  • Have a dedicated function for building frame nodes, making it easier to see where they are created.

Summary

This release is the result of a couple of months work, and somwhat means that proper re-loading of cached results is becoming in sight. The reloading of modules still fails for some things, and more changes will be needed, but with that out of the way, Nuitka's footprint is about to drop and making it then absolutely scalable. Something considered very important before starting to trace more information about values.

This next thing big ought to be one thing that structurally holds Nuitka back from generating C level performance code with say integer operations.

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