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Changelog

Source: NEWS.md

pjrt (development version)

Performance

  • A PJRTBuffer now memoizes its immutable metadata (dtype, shape, and device) on first access, so repeated element_type() / dimensions() reads no longer issue a PJRT C API call each time.

Bug fixes

  • check_err() no longer leaks the underlying PJRT_Error when converting a plugin error into an R exception.
  • Reading a buffer back to the host now respects the device buffer’s actual memory layout. A non-row-major (but untiled) executable output — e.g. one pinned to a column-major layout via mhlo.layout_mode — is reordered correctly instead of being returned transposed. A layout the readback cannot faithfully reorder (strided, tiled, or rank-mismatched) now raises a clear error rather than silently returning wrong data.

Features

  • pjrt_buffer(), pjrt_scalar(), and pjrt_execute() now call R’s garbage collector and retry once when the plugin reports RESOURCE_EXHAUSTED. Unreferenced PJRTBuffer external pointers are finalized between attempts so their device memory is released before the retry.
  • The first time a PJRT plugin needs to be downloaded, interactive sessions now ask for confirmation before downloading (similar to torch). Non-interactive sessions no longer download automatically. The PJRT_INSTALL environment variable overrides this: set it to "1" to always download without asking, or "0" to never download.
  • Added an install_pjrt() function which is a slight convenience wrapper for downloading the plugins.
  • Added the Rtree module (pjrt’s R analog of JAX’s pytree), which includes functions like build_tree(), flatten(), unflatten(), etc..
  • Added dispatcher() and dispatch(), a native (C++) eager-dispatch engine: an executable cache keyed on the inputs’ structure and abstract values, which calls back into R to compile only on a cache miss. Its default backend = "pjrt" runs a compiled PJRT executable natively; any other backend runs through a compiled R closure. It is intended to be used in {anvl}. Ideally this would live in a library of its own, but we have included it here for convenience.
  • inspect_hlo() returns the HLO intermediate representations the XLA compiler produces for a program – the input (before_optimizations) and optimized (after_optimizations) HLO – to help debug compilation (#194). Enable it by setting the dump flags in XLA_FLAGS (e.g. --xla_dump_to=<dir> --xla_dump_hlo_as_text) at the start of the session, before the first compilation; inspect_hlo() errors with instructions if they are not set.

Internal

  • The test suite now only runs when the PJRT_TEST environment variable is set to "1", so it is skipped on CRAN (where the required PJRT plugin cannot be downloaded). CI sets PJRT_TEST=1.

pjrt 0.4.0

Features

  • Added QR, LU, SVD, and symmetric eigendecomposition support on both CPU and CUDA via the FFI registration mechanism.
  • Added an vignette on how to register custom calls via the FFI registration mechanisms with coverage of both CUDA and CPU-specific aspects.
  • Added support for the bit64 package to better support long integers.
  • pjrt_buffer(), pjrt_scalar(), and as_array() gain a check argument (default FALSE). When TRUE, the call errors instead of silently losing information: on input if data contains NAs, on output if the materialized R vector contains a value that’s indistinguishable from NA or that has wrapped through the integer container.
  • as_array() on a ui32 buffer now returns a bit64::integer64 instead of a base integer, so values >= 2^31 round-trip losslessly rather than wrapping to negative.

pjrt 0.3.0

Features

  • Added buffer_copy() function to copy buffer between devices.
  • New pjrt_register_custom_call() allows external packages to register C/C++ XLA FFI handlers with the PJRT plugin. Registration is deferred until the plugin loads, so handlers can be registered during .onLoad().
  • pjrt_device() now returns cached PJRTDevice instances, so repeated calls for the same device yield objects with stable identity (useful for hashing and caching, e.g. in anvl’s JIT).

Bug fixes

  • The configure script now uses the protoc compiler from the same installation as the linked protobuf library, preventing version mismatches when multiple protobuf versions are installed.
  • Compiling a program for a specific CPU device (e.g. cpu:1) now targets that device instead of silently falling back to cpu:0.
  • Fixed device targeting when compiling against a distributed PJRT client, where global device IDs and local hardware ordinals diverge.

Error messages

  • Improved error message when attempting to use CUDA on unsupported OS or platform.

pjrt 0.2.0

Asynchronous API

Operations such as host <-> device transfers and program execution were previously only synchronous. Now, they are asynchronous which has considerable performance benefits, especially on GPU. Specifically:

  • pjrt_buffer() and pjrt_execute() return immediately, but the returned buffer is not necessarily ready. To await a transfer or computation of a buffer, use await(). However, this is handled within PJRT, so this function never has to be called by a user.
  • as_array() is still synchronous, but there is now the asynchronous version as_array_async() but this is rarely needed. If used, it returns a PJRTArrayPromise object which can be converted to an R array/vector via value().
  • To check whether a PJRTBuffer or PJRTArrayPromise is ready, use is_ready().

Features

  • Added dtype support for PJRTBuffers via the tengen::dtype S3 generic. "bool" is now accepted as an alias for "i1"/"pred".
  • Accept DataType objects in the dtype parameter of pjrt_buffer().
  • Support device argument in pjrt_compile().

Bug fixes

  • Protect from segfaults in raw to buffer conversion.
  • Protect from segfault during device mismatch in pjrt_execute().

Platforms & Installation

  • Added support for Linux ARM (aarch64) using CPU backend.
  • Simplified CUDA installation via the cuda12.8 package, which now only requires compatible drivers to be installed.

Miscellaneous

  • The printer for PJRTBuffer now uses "bool" instead of "pred" to avoid discrepancies with {anvl}.

pjrt 0.1.1

Bug fixes

  • Fix formatting of +-Inf/NaN for f64

pjrt 0.1.0

  • Initial release