Fortran

Six rows are pure Fortran: three JSON libraries (json-fortran, jonquil, rojff), TOML (toml-f), MessagePack (fortran-messagepack), and an in-tree little-endian baseline (custom-binary). Those rows are bytes on the five suite types. hdf5-fortran, netcdf-fortran, and adios2 time the array data set (grid and grid_window) from config/library/array.yaml. They do not emit suite rows, so they stay out of all@. hdf5-fortran is the official HDF5 Fortran API on the core virtual file driver, so it is bytes. netcdf-fortran and adios2 have no bytes API. Their CSV rows are stream / native, and they are published through config/file-only.txt.

Numbers for this language appear on the Dashboard after a publication run. These times cannot be ranked against another language.

Runtime

What it is

Fortran is the language of a large share of numerical and scientific programs. This suite runs a batch program built by fpm and executed as one process. It is not a compiler-runtime intrinsic and not a C library with a thin iso_c_binding shell.

	This suite
Compiler	GNU Fortran 13 or newer. `check-host-requirements.sh fortran` rejects gfortran 11 and 12. CI installs `gfortran-13` and that image's HDF5 Fortran package, which share one module format.
Packages	fpm 0.13 (`fortran/fpm.toml`)
Prepare	`./scripts/install-host-requirements.sh fortran` puts fpm in `~/.local/bin`. The compiler and zlib/zstd headers come from the system.
Run	`fortran/scripts/run-benchmarks.sh`
Memory	The process allocator. There is no garbage collector. `MemoryPeakBytes` is 0 because this runner does not sample the allocator.

What this suite runs

The timed call is the library's own string or buffer API: build the document, serialize, then parse that buffer back. Schema setup is not a separate step. These libraries do not compile a schema.

custom-binary is the control row. It is the suite's length-prefixed layout, not a format anyone else publishes.

What changes the numbers

json-fortran is built with -DINT64 and -DREAL64, so json_IK is int64 and epoch milliseconds stay JSON integers. rojff's integer kind is the compiler default, int32. Values outside that range are JSON numbers and are read back with nint. They are exact below 2^53. fortran-messagepack stores those timestamps as MessagePack integers.

hdf5-fortran, netcdf-fortran, and adios2 write one float64 dataset named grid (512×512) and read it back. grid_window writes that same array and reads the interior window at (128, 64) size 256×128. hdf5-fortran times H5Pset_fapl_core with backing store off. The byte size is H5Fget_file_image after a global flush. The window read is H5Sselect_hyperslab. netcdf-fortran does not use NF90_DISKLESS: that flag discards the file on close, so there is no buffer and no honest size. The row times a real NetCDF-4 file. The window read passes 1-based start and count. adios2 is the official Fortran binding over the C++ core, serial, MPI off, engine BP5. BP5 writes a directory. The size is the sum of the file sizes. The window read is adios2_set_selection. IO declaration and the BP5 engine selection sit outside the repetition clock.

A batch of more than one record is a table with a records array, including the JSON rows. TOML has no bare array at the root, and one envelope keeps the readers aligned.

Text is compact. Nothing is pretty-printed inside the timer.

Suite-specific gotchas

-DINT64 and -DREAL64 are on the fpm command line (fortran/scripts/fpm-env.sh). The other Fortran dependencies are not .F90 files, so those macros do not change their integer kind.

fpm's package name for this runner is gld-fortran-bench. It must not match a dependency name, or fpm will not fetch that dependency.

rojff is pinned to commit 9f68e5aa4c12b32720d4224f1ac279bfd7d77b93. It has no GitHub release. The version column shows the short id 9f68e5aa4c12.

Where to go next

How to install the toolchain and run the benchmark: fortran/README.md. The compiler is gfortran. The package runner is fpm.

Benchmark runner

Directory: fortran/
Output: logs/fortran/YYYY-MM-DD-HHMMSS.csv (Language=fortran, times in nanoseconds)
Runner: fortran/scripts/run-benchmarks.sh {smoke|all-single|full|research}
Smoke: json-fortran, message, the smoke repetition count
Schedule: the C block_shuffle implementation (c/src/schedule.c), not a second shuffle
Interchange rows are bytes. netcdf-fortran and adios2 emit stream / native only.

Serializers

Name	Category	Package	Stream	Notes
json-fortran	JSON	jacobwilliams/json-fortran	bytes	`json_core` serialize / deserialize. Built with `-DINT64` so epoch milliseconds stay JSON integers
jonquil	JSON	toml-f/jonquil	bytes	`json_dumps` / `json_loads` on the toml-f model
rojff	JSON	everythingfunctional/rojff	bytes	`to_compact_string` / `parse_json_from_string`. int32 kind; wider integers are JSON numbers
toml-f	Text	toml-f/toml-f	bytes	`toml_serialize` / `toml_loads`. TOML 1.0
fortran-messagepack	Binary	synthfi/fortran-messagepack	bytes	`pack_alloc` / `unpack`, including int64
custom-binary	Binary	harness	bytes	Little-endian length-prefixed baseline
hdf5-fortran	HDF5	HDF-Group/hdf5	bytes	Array data set. Core driver. One dataset `grid`. Hyperslab on `grid_window`
netcdf-fortran	NetCDF	Unidata/netcdf-fortran	file	Array data set. Real NetCDF-4 file. File-only. Window uses 1-based start
adios2	ADIOS2	ornladios/ADIOS2	file	Array data set. Serial BP5 directory. File-only. Window uses `adios2_set_selection`

Specifics

Why each library exists, what problem it was written to solve, and how. Names link to the source repository (or the in-tree path this suite times). A version after the name is the SerializerVersion this runner writes.

json-fortran · `9.3.1`

JSON-Fortran is a modern Fortran JSON API. It exists so Fortran programs can read and write JSON without calling a C library. This row times json_core serialize and deserialize. The runner builds it with -DINT64 and -DREAL64, so json_IK is int64 and json_RK is real64. Epoch milliseconds stay JSON integers.

jonquil · `0.3.2`

Jonquil is a JSON library for Fortran, built on TOML Fortran. It exists so a Fortran program can parse and serialize JSON with the same document model as toml-f. This row times json_dumps and json_loads.

rojff · `9f68e5aa4c12`

rojff (Return of JSON for Fortran) is a pure Fortran JSON value tree. It was written to construct JSON faster than earlier Fortran JSON libraries, with functional constructors and a move API. This row times to_compact_string and parse_json_from_string. Its integer kind is the compiler's default integer, int32 here. Values outside that range are written as JSON numbers so the integer reader does not overflow, and are read back with nint.

toml-f · `0.5.2`

TOML Fortran is a TOML 1.0 parser and serializer for Fortran. It exists so Fortran projects can load and save configuration as TOML. This row times toml_serialize and toml_loads. A batch of more than one record is a table with a records array, because TOML has no bare array at the root. The JSON rows use the same envelope so one reader serves both.

fortran-messagepack · `0.3.1`

fortran-messagepack is a pure Fortran MessagePack library. MessagePack exists as a compact binary form of JSON-like values. This row times pack_alloc and unpack. Integers are MessagePack integers, including int64 epoch milliseconds.

custom-binary · `v2-1.0`

This is the suite's length-prefixed V2 baseline, not a published format. It exists so every language has a simple binary control point: write fields with explicit lengths, read them back, no schema compiler.

hdf5-fortran · `1.10.7`

hdf5-fortran is the official HDF5 Fortran API. This row times the core virtual file driver on the array data set: one contiguous float64 dataset grid, backing store off, and the byte size is the flushed file image. grid_window reads an interior hyperslab.

netcdf-fortran

netcdf-fortran is the official NetCDF Fortran API. NF90_DISKLESS discards the file on close, so this row times a real NetCDF-4 file on the array data set: one NF90_DOUBLE variable grid. grid_window reads with 1-based start and count. The CSV mode is stream, StreamMode is native, and the size is the file size. It is published through config/file-only.txt.

adios2 · `2.10.2`

adios2 is the official ADIOS2 Fortran binding over the C++ core. The build is serial, MPI is off, and the engine is BP5. This row times one float64 variable grid in a BP5 directory. grid_window sets a 0-based selection before get. The API has no bytes buffer. The size is the sum of the file sizes. It is published through config/file-only.txt.

Not registered

These were considered and left off the leaderboard.

fson and jsonff are Fortran JSON libraries. jsonff was not built into this runner. fson is the older Fortran 95 stack and was not shown to round-trip the five suite types here.
fortjson was not shown to round-trip the five suite types.
yaFyaml parses a YAML subset for gFTL and can print a node. It needs gfortran 12 and gFTL. This runner did not qualify that print path on the five suite types. fortran-yaml, qfyaml, and NOAA Fyaml were not shown to round-trip those types either.
fortran-yaml-c, fortran-yaml-cpp, YAJL-Fort, and mpack-fortran call C or C++ libraries. They measure that library plus an FFI crossing. They are not separate leaderboard rows.
FoX, FoXy, and xml-fortran are XML. XML is outside the compliance catalog, and none of them was qualified on the five suite types.
h5fortran and nc4fortran open a file name. They were not shown to select the HDF5 core driver or a NetCDF memory buffer, so they are not extra rows.
fortran-hdf5-interface and h5fortran-mpi are not timed.
csv-fortran, BeFoR64, and VTKFortran move arrays or meshes. They are not interchange standards in this catalog.
There is no pure Fortran CBOR, Protocol Buffers, Avro, BSON, FlatBuffers, Ion, Arrow, or Parquet library in this runner.