Introduction to spead2

spead2 is an implementation of the SPEAD protocol, with both Python and C++ bindings. The 2 in the name indicates that this is a new implementation of the protocol; the protocol remains essentially the same. Compared to the PySPEAD implementation, spead2:

  • is at least an order of magnitude faster when dealing with large heaps;
  • correctly implements several aspects of the protocol that were implemented incorrectly in PySPEAD (bug-compatibility is also available);
  • correctly implements many corner cases on which PySPEAD would simply fail;
  • cleanly supports several SPEAD flavours (e.g. 64-40 and 64-48) in one module, with the receiver adapting to the flavour used by the sender;
  • supports Python 3;
  • supports asynchronous operation, using trollius or asyncio.

Preparation

There is optional support for netmap and ibverbs for higher performance. If the libraries (including development headers) are installed, they will be detected automatically and support for them will be included.

If you are installing spead2 from a git checkout, it is first necessary to run ./bootstrap.sh to prepare the configure script and related files. When building from a packaged download this is not required.

High-performance usage requires larger buffer sizes than Linux allows by default. The following commands will increase the permitted buffer sizes on Linux:

sysctl net.core.wmem_max=16777216
sysctl net.core.rmem_max=16777216

Note that these commands are not persistent across reboots, and the settings need to be stored in /etc/sysctl.conf or /etc/sysctl.d.

Installing spead2 for Python

The only Python dependencies are numpy and six, and trollius on Python versions below 3.4 (for 3.4+, trollius can still be used, and is needed to run the test suite). Running the test suite additionally requires nose, decorator and netifaces, and some tests depend on PySPEAD (they will be skipped if it is not installed). It is also necessary to have the development headers for Python.

There are two ways to install spead2 for Python: compiling from source and installing a binary wheel. The binary wheels are experimental and only recommended if installing from source is not an option.

Python install from source

Installing from source requires a modern C++ compiler supporting C++11 (GCC 4.8+ or Clang 3.5+) as well as Boost (including compiled libraries). At the moment only GNU/Linux and OS X get tested but other POSIX-like systems should work too. There are no plans to support Windows.

Installation works with standard Python installation methods. For example, to install the latest version from PyPI, run:

pip install spead2

Installing a binary wheel

As from version 1.3.2, binary wheels for x86-64 Linux systems are placed on the Github release page. They are still experimental, lack the optional features, and may be slower than installs from source because they are compiled with an old compiler. They are mainly intended for systems where it is not practical to install a new enough C++ compiler or Boost. For this reason, they are currently not provided through PyPI.

After downloading the appropriate wheel for your Python version, install it with pip install filename.

Installing spead2 for C++

spead2 requires a modern C++ compiler supporting C++11 (GCC 4.8+ or Clang 3.5+) as well as Boost (including compiled libraries). At the moment only GNU/Linux and OS X get tested but other POSIX-like systems should work too. There are no plans to support Windows.

The C++ API uses the standard autoconf installation flow i.e.:

./configure [options]
make
make install

For generic help with configuration, see INSTALL in the top level of the source distribution. Optional features are autodetected by default, but can be disabled by passing options to configure (run ./configure -h to see a list of options).

One option that may squeeze out a very small amount of extra performance is --enable-lto to enable link-time optimization. Up to version 1.2.0 this was enabled by default, but it has been disabled because it often needs other compiler or OS-specific configuration to make it work. For GCC, typical usage is

./configure --enable-lto AR=gcc-ar RANLIB=gcc-ranlib

The installation will install some benchmark tools, a static library, and the header files. At the moment there is no intention to create a shared library, because the ABI is not stable.