When running the `profiling.sampling` module in pstats mode, the output
can be emitted in two different ways: text to stdout or a binary file
when the `--output` argument is set.
The current documentation and help text is confusing as it does not
distinguish between these two output formats so it may be surprising to
the user to get different formats depending whether `--output` is set or not.
The bytecode panel appears when a user generates a heatmap with
--opcodes and clicks the button to unfold a line and display the
bytecode instructions. Currently, an empty space appears on the
left where the line number, self, and total columns are displayed.
This area should instead extend those columns, rather than leaving
a gap.
* Add profiling module documentation structure
PEP 799 introduces a new `profiling` package that reorganizes Python's
profiling tools under a unified namespace. This commit adds the documentation
structure to match: a main entry point (profiling.rst) that helps users choose
between profilers, detailed docs for the tracing profiler (profiling-tracing.rst),
and separated pstats documentation.
The tracing profiler docs note that cProfile remains as a backward-compatible
alias, so existing code continues to work. The pstats module gets its own page
since it's used by both profiler types and deserves focused documentation.
* Add profiling.sampling documentation
The sampling profiler is new in Python 3.15 and works fundamentally differently
from the tracing profiler. It observes programs from outside by periodically
capturing stack snapshots, which means zero overhead on the profiled code. This
makes it practical for production use where you can attach to live servers.
The docs explain the key concepts (statistical vs deterministic profiling),
provide quick examples upfront, document all output formats (pstats, flamegraph,
gecko, heatmap), and cover the live TUI mode. The defaults table helps users
understand what happens without any flags.
* Wire profiling docs into the documentation tree
Add the new profiling module pages to the Debugging and Profiling toctree.
The order places the main profiling.rst entry point first, followed by the
two profiler implementations, then pstats, and finally the deprecated profile
module last.
* Convert profile.rst to deprecation stub
The pure Python profile module is deprecated in 3.15 and scheduled for removal
in 3.17. Users should migrate to profiling.tracing (or use the cProfile alias
which continues to work).
The page now focuses on helping existing users migrate: it shows the old vs new
import style, keeps the shared API reference since both modules have the same
interface, and preserves the calibration docs for anyone still using the pure
Python implementation during the transition period.
* Update CLI module references for profiling restructure
Point cProfile to profiling.tracing docs and add profiling.sampling to the
list of modules with CLI interfaces. The old profile-cli label no longer
exists after the documentation restructure.
* Update whatsnew to link to profiling module docs
Enable cross-references to the new profiling module documentation and update
the CLI examples to use the current syntax with the attach subcommand. Also
reference profiling.tracing instead of cProfile since that's the new canonical
name.
This PR implements frame caching in the RemoteUnwinder class to significantly reduce memory reads when profiling remote processes with deep call stacks.
When cache_frames=True, the unwinder stores the frame chain from each sample and reuses unchanged portions in subsequent samples. Since most profiling samples capture similar call stacks (especially the parent frames), this optimization avoids repeatedly reading the same frame data from the target process.
The implementation adds a last_profiled_frame field to the thread state that tracks where the previous sample stopped. On the next sample, if the current frame chain reaches this marker, the cached frames from that point onward are reused instead of being re-read from remote memory.
The sampling profiler now enables frame caching by default.
flow