CHANGELOG.md

Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog.

[Unreleased] - YYYY-MM-DD

Added

• Added hvd.reducescatter() operation with implementations in NCCL, MPI, and Gloo. (#3299)

Changed

• MXNet: Updated allreduce functions to newer op API. (#3299)

• TF: Make TensorFlow output allocations asynchronous when using NCCL backend. (#3464)

Deprecated

• MXNet: Deprecated average argument of allreduce functions. (#3299)

Removed

Fixed

• Fallback to NCCL shared lib if static one is not found. (#3500

[v0.24.2] - 2022-03-10

Fixed

• [Setup] Require fsspec >= 2010.07.0 (#3451)
• Fix ignored cuda arch flags (#3462

[v0.24.1] - 2022-03-03

Fixed

• Extended CMake build script to often find CUDA even if nvcc is not in $PATH. (#3444)

[v0.24.0] - 2022-03-01

Added

• Ray: Added elastic keyword parameters to RayExecutor API: This API supports both static (non-elastic) and elastic Horovod jobs. (#3190)
• TensorFlow: Added in-place broadcasting of variables. (#3128)
• Elastic: Added support for resurrecting blacklisted hosts. (#3319)
• MXNet: Added support for MXNet async dependency engine. (#3242, #2963)
• Spark/Lightning: Added history to lightning estimator. (#3214)

Changed

• Moved to CMake version 3.13 with first-class CUDA language support and re-enabled parallelized builds. Uses a temporary installation of CMake if CMake 3.13 is not found. (#3261, #3371)
• Moved released Docker image horovod and horovod-cpu to Ubuntu 20.04 and Python 3.8. (#3393)
• Spark Estimator: Don't shuffle row groups if training data requires non-shuffle (#3369)
• Spark/Lightning: Reduced memory footprint of async dataloader. (#3239)
• Elastic: Improved handling NCCL errors under elastic scenario. (#3112)
• Spark/Lightning: Do not overwrite model with checkpoint by default. (#3201)
• Make checkpoint name optional so that user can save to h5 format. (#3411)

Deprecated

• Deprecated ElasticRayExecutor APIs in favor of the new RayExecutor API. (#3190)

Removed

• Spark: Removed h5py<3 constraint as this is not needed anymore for Tensorflow >2.5.0. (#3301)

Fixed

• Elastic Spark: Fixed indices in initial task-to-task registration. (#3410)
• PyTorch: Fixed GIL-related deadlock with PyTorch 1.10.1. (#3352)
• PyTorch: Fixed finalization of ProcessSetTable. (#3351)
• Fixed remote trainers to point to the correct shared lib path. (#3258)
• Fixed imports from tensorflow.python.keras with tensorflow 2.6.0+. (#3403)
• Fixed Adasum communicator init logic. (#3379)
• Lightning: Fixed resume logger. (#3375)
• Fixed the checkpoint directory structure for pytorch and pytorch lightning. (#3362)
• Fixed possible integer overflow in multiplication. (#3368)
• Fixed the pytorch_lightning_mnist.py example. (#3245, #3290)
• Fixed barrier segmentation fault. (#3313)
• Fixed hvd.barrier() tensor queue management. (#3300)
• Fixed PyArrow "list index out of range" IndexError. (#3274)
• Elastic: Fixed all workers sometimes failing on elastic Horovod failure. (#3264)
• Spark/Lightning: Fixed setting limit_train_batches and limit_val_batches. (#3237)
• Elastic: Fixed ElasticSampler and hvd.elastic.state losing some indices of processed samples when nodes dropped. (#3143)
• Spark/Lightning: Fixed history metrics for estimator serialization. (#3216)
• Ray: Fixed RayExecutor to fail when num_workers=0 and num_hosts=None. (#3210)
• Spark/Lightning: Fixed checkpoint callback dirpath typo. (#3204)

[v0.23.0] - 2021-10-06

Added

• Added process sets to concurrently run collective operations on subsets of Horovod processes in TensorFlow, PyTorch, and MXNet. (#2839, #3042, #3043, #3054, #3083, #3090)
• Added XLA support for Allreduce via tf.function(jit_compile=True). (#3053)
• Added fused buffer scaling and unpack/pack kernels on GPU. (#2973)
• Added support for NCCL on CUDA 11.4. (#3182)
• Added fp16 compression for MXNet. (#2987)
• Added terminate_on_nan flag to Spark Lightning estimator. (#3088)
• Added barrier() API to torch module to support simple synchronization among ranks and to achieve parity with PyTorch DDP and similar frameworks. #3139
• Added params for customizing Tensorboard callback. (#3153)
• Added hvd.cross_rank() for keras. (#3008)
• Added barrier() API to torch module to support simple synchronization among ranks and to achieve parity with PyTorch DDP and similar frameworks. #3139

Changed

• Implemented more asynchronous dependency handling on GPU. (#2963)
• Ray: RayExecutor will now use the current placement group instead of always creating a new one. (#3134)
• Lightning: turned off shuffling for validation dataset. (#2974)
• Ray: RayExecutor will use the current placement group if one exists. (#3134)
• Extended hvd.join() to return the last rank that joined. (#3097

Deprecated

Removed

• Spark/Keras: remove bare Keras support. (#3191)

Fixed

• Fix Horovod develop/editable install mode and incremental builds. (#3074)
• Estimator/Lightning: use lightning datamodule. (#3084)
• Fix Horovod Spark StringType and numpy type mapping issue. (#3146)
• Fixed error in Keras LearningRateScheduler. (#3135)
• Fixed bug in Lightning Profiler on Ray. (#3122)
• Fixed torch op lazy release to prevent OOM in elastic training. (#3110)
• Lightning: Fixed usage of the checkpoint callback. (#3186)
• Fixed MPICH support to use Intel MPI's implementation. (#3148)
• Fixed race condition in PyTorch async dataloader. (#3120)
• Keras: Fixed learning rate scheduler. (#3142, #3135)

[v0.22.1] - 2021-06-10

Added

• Estimator: added support for loading data from S3, GCS, ADLS, and other remote filesystems. (#2927)
• Estimator: added custom Spark data loader interface. (#2938)
• LightningEstimator: added support to supply a logger and associated parameter to control the frequency of logging. (#2926)
• Estimator: added check to ensure all ranks have the same device type. (#2942)

Changed

• Changed behavior from using TensorBoardLogger to now using it as a fallback if a logger is not supplied. (#2926)
• Ray: disabled capturing child tasks in placement group. (#2920)

Fixed

• Fixed hvd.tensorflow.keras.Compression, accidentally removed in v0.22.0. (#2945)
• TorchEstimator: fixed usage of validation_steps in place of validation_steps_per_epoch. (#2918)
• TensorFlow: fixed C++ API for TF v2.6.0. (#2932)
• PyTorch: fixed sparse_allreduce_async for PyTorch v0.10.0. (#2965)

[v0.22.0] - 2021-05-18

Added

• Added pytorch_lightning spark estimator which enables training pytorch_lightning models. (#2713)
• Added NVTX tracing hooks for profiling with Nsight Systems. (#2723)
• Added a generic num_workers API for RayExecutor (#2870)
• Supports Ray Client without code changes. (#2882)
• Supports inmemory cache option for Keras Estimator. (#2896)
• Added FP16 support for GPU tensor in mxnet. (#2915)
• Added response caching for allgather operations. (#2872)
• Estimator: add petastorm reader_pool_type into constructor (#2903)

Changed

• Changed alltoall to return the received splits as a second return value if non-uniform splits are sent. (#2631)
• Changed RayExecutor to use Ray Placement Groups for worker colocation. (#2824)
• Changed Inmemory dataloader usage for Torch Estimator with petastorm v0.11.0 release. (#2896)

Fixed

• Changed RayExecutor to use Ray node ID to enable multi-container:single-host setups. (#2883)
• Support sparse gradients aggregation in TF1 Keras. (#2879)
• Respect global_step parameter for LegacyOptimizers when aggregating gradients. (#2879)
• Fixed compatibility with PyTorch 1.9.0. (#2829)

[v0.21.3] - 2021-02-15

Added

• Add groups parameter in DistributedOptimizer for custom allreduce groups. (#2523)

Removed

• Removed num_groups parameter in DistributedOptimizer, replaced with groups. (#2523)

Fixed

• Fixed worker desynchronization deadlock issue in TensorFlow 2.4. (#2647)
• Deduped Keras LearningRateWarmupCallback log after gradual learning rate warmup. (#2661)

[v0.21.2] - 2021-02-08

Added

• Added support for Intel(R) MPI in horovodrun. (#2374)
• Add support for callbacks in Ray Elastic Executor. (#2639)
• Added forwarding of stdout/stderr captured to driver over Gloo. (#2646)

Fixed

• Fixed broadcast_optimizer_state to handle NoneType params for PyTorch 1.8. (#2624)
• Fixed local_rank support for Ray. (#2596)
• Fixed DL estimators to obtain the output df schema without sampling the input. (#2611)
• Fixed wrong default for horovod.tensorflow.keras.allreduce average (#2627)

[v0.21.1] - 2021-01-06

Added

• Added in-memory dataset caching param to TorchEstimator. (#2434)
• Added val_batch_size param to the Estimator API. (#2505)
• Added support for TorchScript modules when using TorchEstimator. (#2494)

Changed

• Migrated to oneCCL aligned with oneAPI specification v1.0. (#2513)
• Added knob to set cache hint for oneCCL allreduce. (#2560)
• Renamed horovodrun arg --ccl-bgt-affinity to --thread-affinity. (#2562)
• Changed default build parallelism from -j8 to -j1 to address potential race condition. (#2572)

Fixed

• Fixed building Horovod for ROCm PyTorch with newer hipify script. (#2360)
• Fixed "Executable class" support for Ray. (#2510)
• Fixed TorchEstimator returning model without switching to eval mode. (#2517)
• Remove ssh reliance for Ray elastic training. (#2528)
• Fixed error handling for changing framework without reinstalling horovod. (#2529)
• Fixed "Intermediate path does not exist" error with DBFSLocalStore. (#2526)
• Avoid synchronization if workers are only shrinked in elastic mode. (#2514)
• Fixed Ray resource test. (#2575)
• Fixed usage of env variable HOROVOD_GLOO_TIMEOUT_SECONDS with horovodrun. (#2571)

[v0.21.0] - 2020-11-23

Added

• Added support for backward_passes_per_step > 1 for TF Keras graph mode. (#2346)
• Added support for backward_passes_per_step > 1 for TF Keras eager execution. (#2371)
• Added support for backward_passes_per_step > 1 for TF LegacyOptimizer in graph mode. (#2401)
• Added grouped allreduce to enable more efficient tensor fusion and deterministic training. (#2453)
• Add support for specifying op and compression in horovod.tensorflow.keras.allreduce(). (#2423)
• Adding support for batched D2D memcopy kernel on GPU. (#2435)
• Added schema inference in Spark Estimator without sampling. (#2373)
• Added Store.create("dbfs:/") mapping to DBFSLocalStore("/dbfs/..."). (#2376)

Changed

• Changed Keras callbacks to require parameter initial_lr of LearningRateScheduleCallback and LearningRateWarmupCallback. (#2459)
• Changed default cycle time from 5ms to 1ms and fusion threshold from 64MB to 128MB. (#2468)

Fixed

• Fixed support for TensorFlow v2.4.0. (#2381)
• Fixed averaging using CUDA half2 implementation one element half buffers. (#2375)
• Fixed HOROVOD_THREAD_AFFINITY when using oneCCL. (#2350)
• Added timeout to SSH check in horovodrun to prevent hanging. (#2448)
• Added HOROVOD_GLOO_TIMEOUT_SECONDS value to error messages. (#2436)
• Fixed race condition in dynamic timeline API. (#2341)
• Fixed --log-hide-timestamp to apply to driver logs with Gloo. (#2388)
• Fixed the search order of Eigen and Flatbuffers paths. (#2473)
• Fixed type checks in TorchEstimator to correctly use isinstance(). (#2480)

[0.20.3] - 2020-10-01

Added

• Added Elastic Ray integration. (#2291)

Changed

• Removed dependency on SSH access for Ray. (#2275)

[0.20.2] - 2020-09-25

Fixed

• Fixed building Horovod without HOROVOD_WITHOUT_MXNET when MXNet is not installed. (#2334)

[0.20.1] - 2020-09-25

Added

• Added Databricks storage DBFSLocalStore and support for GPU-aware scheduling to horovod.spark Estimator. (#2234)
• Added ElasticSampler and PyTorch Elastic ImageNet example. (#2297)
• Added ability to dynamically start and stop timeline programmatically. (#2215)
• Added support for Gloo on macOS. (#2254)
• Exposed name argument to TensorFlow allreduce operation. (#2325)
• Added option to strip outer name scope from Horovod ops in TensorFlow. (#2328)

Fixed

• Fixed usage of VERBOSE=1 when setting custom MAKEFLAGS. (#2239)
• Fixed bugs in Keras Elastic Callback classes. (#2289)
• Fixed RelWithDebInfo build and made it the default with -03 optimizations. (#2305)
• Fixed usage of tf.cond in TensorFlow alltoall gradient. (#2327)
• Fixed allreduce averaging for TF IndexedSlices in ROCm path. (#2279)
• Include stdexcept to handle certain compiler / frameworks that don't include it already. (#2238)
• Fixed Debug builds by setting compiler options based on CMake build type. (#2263)
• Skipped launching zero-sized send/recvs for NCCLAlltoall. (#2273)
• Fixed missing run in tf keras elastic mode. (#2272)
• Fixed loss function in TensorFlow2 elastic synthetic benchmark. (#2265)
• Fixed usage of HOROVOD_MIXED_INSTALL env var in alltoall tests. (#2266)
• Removed keras requirement from Ray example. (#2262)

[0.20.0] - 2020-09-02

Added

• Added bare-metal elastic mode implementation to enable auto-scaling and fault tolerance. (#1849)
• Added Elastic Horovod support for Spark auto-scaling. (#1956)
• Added All-to-All operation for TensorFlow, PyTorch, and MXNet. (#2143)
• Added support for gradient_predivide_factor and averaging in Horovod backend. (#1949)
• Added NCCL implementation of the allgather operation. (#1952)
• Added HOROVOD_GPU_OPERATIONS installation variable to simplify enabling NCCL support for all GPU operations. (#1960)
• Added TensorFlow implementation of SyncBatchNormalization layer. (#2075)
• Added hvd.is_initialized() method. (#2020)
• Added hvd.allgather_object function for TensorFlow, PyTorch, and MXNet. (#2166)
• Added hvd.broadcast_object function for MXNet. (#2122)
• Added label_shapes parameter to KerasEstimator and TorchEstimator. (#2140)
• Added optional modelCheckPoint callback to KerasEstimator params. (#2124)
• Added ssh_identity_file argument to horovodrun. (#2201)
• Added support for horovodrun on kubeflow/mpi-job. (#2199)
• Added Ray integration. (#2218)

Changed

• Moved horovod.run.runner.run to horovod.run. (#2099)
• HOROVOD_THREAD_AFFINITY accepts multiple values, one for every Horovod rank (#2131)
• Migrated build system for native libraries to CMake (#2009)

Deprecated

• HOROVOD_CCL_BGT_AFFINITY is deprected. Use HOROVOD_THREAD_AFFINITY instead (#2131)

Removed

• Dropped support for Python 2. (#1954)
• Dropped support for TensorFlow < 1.15. (#2169)
• Dropped support for PyTorch < 1.2. (#2086)

Fixed

• Fixed MXNet allgather implementation to correctly handle resizing the output buffer. (#2092)
• Fixed Keras Spark Estimator incompatibility with TensorFlow 1.15 due to tf.autograph. (#2069)
• Fixed API compatibility with PyTorch 1.6. (#2051)
• Fixed Keras API compatibility with TensorFlow 2.4.0. (#2178)
• Fixed allgather gradient for TensorFlow 2 in cases where the tensor shape is not known during graph construction. (#2121)
• Fixed running using Gloo with an imbalanced number of workers per host. (#2212)