.. S4U (Simgrid for you) is the next interface of SimGrid, expected to be released with SimGrid 4.0. .. .. Even if it is not completely rock stable yet, it may well already fit .. your needs. You are welcome to try it and report any interface .. glitches that you see. Be however warned that the interface may change .. until the final release. You will have to adapt your code on the way. .. .. This file follows the ReStructured syntax to be included in the .. documentation, but it should remain readable directly. S4U Examples ************ SimGrid comes with an extensive set of examples, documented on this page. Most of them only demonstrate one single feature, with some larger examplars listed below. The C++ examples can be found under examples/s4u while python examples are in examples/python. Each such directory contains the source code (also listed from this page), and the so-called tesh file containing how to call the binary obtained by compiling this example and also the expected output. Tesh files are used to turn each of our examples into an integration test. Some examples also contain other files, on need. A good way to bootstrap your own project is to copy and combine some of the provided examples to constitute the skeleton of what you plan to simulate. =========================== Actors: the Active Entities =========================== Starting and Stoping Actors --------------------------- - **Creating actors:** Most actors are started from the deployment XML file, but there is other methods. This example show them all. `examples/python/actor-create/actor-create_d.xml `_ - |cpp| `examples/s4u/actor-create/s4u-actor-create.cpp `_ - |py| `examples/python/actor-create/actor-create.py `_ - **React to the end of actors:** You can attach a callback to the end of actors. There is two ways of doing so, depending of whether you want your callback to be executed when a specific actor ends (with ```this_actor::on_exit()```) or whether it should be executed when any actor ends (with ```Actor::on_destruction()```) - |cpp| `examples/s4u/actor-exiting/s4u-actor-exiting.cpp `_ - **Kill actors:** Actors can forcefully stop other actors. - |cpp| `examples/s4u/actor-kill/s4u-actor-kill.cpp `_ :cpp:func:`void simgrid::s4u::Actor::kill(void)`, :cpp:func:`void simgrid::s4u::Actor::kill_all()`, :cpp:func:`simgrid::s4u::this_actor::exit`. - |py| `examples/python/actor-kill/actor-kill.py `_ :py:func:`simgrid.Actor.kill`, :py:func:`simgrid.Actor.kill_all`, :py:func:`simgrid.this_actor.exit`. - **Controling the actor life cycle from the XML:** You can specify a start time and a kill time in the deployment file. |br| `examples/s4u/actor-lifetime/s4u-actor-lifetime.cpp `_ |br| `examples/s4u/actor-lifetime/s4u-actor-lifetime_d.xml `_ - **Daemonize actors:** Some actors may be intended to simulate daemons that run in background. This example show how to transform a regular actor into a daemon that will be automatically killed once the simulation is over. - |cpp| `examples/s4u/actor-daemon/s4u-actor-daemon.cpp `_ - |py| `examples/python/actor-daemon/actor-daemon.py `_ Inter-Actors Interactions ------------------------- See also the examples on :ref:`inter-actors communications ` and the ones on :ref:`classical synchronization objects `. - **Suspend and Resume actors:** Actors can be suspended and resumed during their executions. - |cpp| `examples/s4u/actor-suspend/s4u-actor-suspend.cpp `_ :cpp:func:`simgrid::s4u::this_actor::suspend()`, :cpp:func:`simgrid::s4u::Actor::suspend()`, :cpp:func:`simgrid::s4u::Actor::resume()`, :cpp:func:`simgrid::s4u::Actor::is_suspended()`. - |py| `examples/python/actor-suspend/actor-suspend.py `_ :py:func:`simgrid.this_actor.suspend()`, :py:func:`simgrid.Actor.suspend()`, :py:func:`simgrid.Actor.resume()`, :py:func:`simgrid.Actor.is_suspended()`. - **Migrating Actors:** Actors can move or be moved from a host to another very easily. - |cpp| `examples/s4u/actor-migrate/s4u-actor-migrate.cpp `_ :cpp:func:`simgrid::s4u::this_actor::migrate()` - |py| `examples/python/actor-migrate/actor-migrate.py `_ :py:func:`simgrid.this_actor.migrate()` - **Waiting for the termination of an actor:** (joining on it) You can block the current actor until the end of another actor. - |cpp| `examples/s4u/actor-join/s4u-actor-join.cpp `_ :cpp:func:`simgrid::s4u::Actor::join()` - |py| `examples/python/actor-join/actor-join.py `_ :py:func:`simgrid.Actor.join()` - **Yielding to other actors**. The ```yield()``` function interrupts the execution of the current actor, leaving a chance to the other actors that are ready to run at this timestamp. - |cpp| `examples/s4u/actor-yield/s4u-actor-yield.cpp `_ :cpp:func:`simgrid::s4u::this_actor::yield()` - |py| `examples/python/actor-yield/actor-yield.py `_ :py:func:`simgrid.this_actor.yield_()` Traces Replay as a Workload --------------------------- This section details how to run trace-driven simulations. It is very handy when you want to test an algorithm or protocol that only react to external events. For example, many P2P protocols react to user requests, but do nothing if there is no such event. In such situations, you should write your protocol in C++, and separate the workload that you want to play onto your protocol in a separate text file. Declare a function handling each type of the events in your trace, register them using :cpp:func:`xbt_replay_action_register()` in your main, and then run the simulation. Then, you can either have one trace file containing all your events, or a file per simulated process: the former may be easier to work with, but the second is more efficient on very large traces. Check also the tesh files in the example directories for details. - **Communication replay:** Presents a set of event handlers reproducing classical communication primitives (asynchronous send/receive at the moment). |br| `examples/s4u/replay-comm/s4u-replay-comm.cpp `_ - **I/O replay:** Presents a set of event handlers reproducing classical I/O primitives (open, read, close). |br| `examples/s4u/replay-storage/s4u-replay-storage.cpp `_ ========================== Activities: what Actors do ========================== .. _s4u_ex_communication: Communications on the Network ----------------------------- - **Basic asynchronous communications:** Illustrates how to have non-blocking communications, that are communications running in the background leaving the process free to do something else during their completion. - |cpp| `examples/s4u/async-wait/s4u-async-wait.cpp `_ :cpp:func:`simgrid::s4u::Mailbox::put_async()` and :cpp:func:`simgrid::s4u::Comm::wait()` - |py| `examples/python/async-wait/async-wait.py `_ :py:func:`simgrid.Mailbox.put_async()` :py:func:`simgrid.Comm.wait()` - **Waiting for all communications in a set:** The `wait_all()` function is useful when you want to block until all activities in a given set have completed. - |cpp| `examples/s4u/async-waitall/s4u-async-waitall.cpp `_ :cpp:func:`simgrid::s4u::Comm::wait_all()` - |py| `examples/python/async-waitall/async-waitall.py `_ :py:func:`simgrid.Comm.wait_all()` - **Waiting for the first completed communication in a set:** The `wait_any()` function is useful when you want to block until one activity of the set completes, no matter which terminates first. - |cpp| `examples/s4u/async-waitany/s4u-async-waitany.cpp `_ :cpp:func:`simgrid::s4u::Comm::wait_any()` - |py| `examples/python/async-waitany/async-waitany.py `_ :py:func:`simgrid.Comm.wait_any()` .. todo:: review the `ready` and `waituntil` examples and add them here. .. _s4u_ex_execution: Executions on the CPU --------------------- - **Basic execution:** The computations done in your program are not reported to the simulated world, unless you explicitely request the simulator to pause the actor until a given amount of flops gets computed on its simulated host. Some executions can be given an higher priority so that they get more resources. - |cpp| `examples/s4u/exec-basic/s4u-exec-basic.cpp `_ - |py| `examples/python/exec-basic/exec-basic.py `_ - **Asynchronous execution:** You can start asynchronous executions, just like you would fire background threads. - |cpp| `examples/s4u/exec-async/s4u-exec-async.cpp `_ - |py| `examples/python/exec-async/exec-async.py `_ - **Remote execution:** You can start executions on remote hosts, or even change the host on which they occur during their execution. - |cpp| `examples/s4u/exec-remote/s4u-exec-remote.cpp `_ - |py| `examples/python/exec-remote/exec-remote.py `_ - **Parallel executions:** These objects are convenient abstractions of parallel computational kernels that span over several machines, such as a PDGEM and the other ScaLAPACK routines. Note that this only works with the "ptask_L07" host model (``--cfg=host/model:ptask_L07``). |br| `examples/s4u/exec-ptask/s4u-exec-ptask.cpp `_ - **Using Pstates on a host:** `examples/platforms/energy_platform.xml `_ shows how define a set of pstates in the XML. The current pstate of an host can then be accessed and changed from the program. - |cpp| `examples/s4u/exec-dvfs/s4u-exec-dvfs.cpp `_ :cpp:func:`simgrid::s4u::Host::get_pstate_speed` and :cpp:func:`simgrid::s4u::Host::set_pstate`. - |py| `examples/python/exec-dvfs/exec-dvfs.py `_ :py:func:`Host.get_pstate_speed` and :py:func:`Host.set_pstate`. I/O on Disks and Files ---------------------- SimGrid provides two levels of abstraction to interact with the simulated storages. At the simplest level, you simply create read and write actions on the storage resources. - **Access to raw storage devices:** This example illustrates how to simply read and write data on a simulated storage resource. |br| `examples/s4u/io-storage-raw/s4u-io-storage-raw.cpp `_ The FileSystem plugin provides a more detailed view, with the classical operations over files: open, move, unlink, and of course read and write. The file and disk sizes are also dealt with and can result in short reads and short write, as in reality. - **File Management:** This example illustrates the use of operations on files (read, write, seek, tell, unlink, etc). |br| `examples/s4u/io-file-system/s4u-io-file-system.cpp `_ - **Remote I/O:** I/O operations on files can also be done in a remote fashion, i.e. when the accessed disk is not mounted on the caller's host. |br| `examples/s4u/io-file-remote/s4u-io-file-remote.cpp `_ .. _s4u_ex_IPC: Classical synchronization objects --------------------------------- - **Mutex:** Shows how to use simgrid::s4u::Mutex synchronization objects. |br| `examples/s4u/synchro-mutex/s4u-synchro-mutex.cpp `_ - **Barrier:** Shows how to use simgrid::s4u::Barrier synchronization objects. |br| `examples/s4u/synchro-barrier/s4u-synchro-barrier.cpp `_ - **Semaphore:** Shows how to use simgrid::s4u::Semaphore synchronization objects. |br| `examples/s4u/synchro-semaphore/s4u-synchro-semaphore.cpp `_ ============================= Interacting with the Platform ============================= - **Retrieving the list of hosts matching a given criteria:** Shows how to filter the actors that match a given criteria. |br| `examples/s4u/engine-filtering/s4u-engine-filtering.cpp `_ - **User-defined properties:** You can attach arbitrary information to most platform elements from the XML file, and then interact with these values from your program. Note that the changes are not written permanently on disk, in the XML file nor anywhere else. They only last until the end of your simulation. - :cpp:func:`simgrid::s4u::Actor::get_property()` and :cpp:func:`simgrid::s4u::Actor::set_property()` - :cpp:func:`simgrid::s4u::Host::get_property()` and :cpp:func:`simgrid::s4u::Host::set_property()` - :cpp:func:`simgrid::s4u::Link::get_property()` and :cpp:func:`simgrid::s4u::Link::set_property()` - :cpp:func:`simgrid::s4u::NetZone::get_property()` and :cpp:func:`simgrid::s4u::NetZone::set_property()` |br| `examples/s4u/platform-properties/s4u-platform-properties.cpp `_ |br| `examples/s4u/platform-properties/s4u-platform-properties_d.xml `_ |br| `examples/platforms/prop.xml `_ - **Specifying state profiles:** shows how to specify when the resources must be turned off and on again, and how to react to such failures in your code. |br| `examples/platforms/small_platform_with_failure.xml `_ |br| The state profiles in `examples/platforms/profiles `_ - **Specifying speed profiles:** shows how to specify an external load to resources, variating their peak speed over time. |br| `examples/platforms/small_platform_profile.xml `_ |br| The speed, bandwidth and latency profiles in `examples/platforms/profiles `_ ================= Energy Simulation ================= - **Describing the energy profiles in the platform:** This platform file contains the energy profile of each links and hosts, which is necessary to get energy consumption predictions. As usual, you should not trust our example, and you should strive to double-check that your instanciation matches your target platform. |br| `examples/platforms/energy_platform.xml `_ - **Consumption due to the CPU:** This example shows how to retrieve the amount of energy consumed by the CPU during computations, and the impact of the pstate. |br| `examples/s4u/energy-exec/s4u-energy-exec.cpp `_ - **Consumption due to the network:** This example shows how to retrieve and display the energy consumed by the network during communications. |br| `examples/s4u/energy-link/s4u-energy-link.cpp `_ - **Modeling the shutdown and boot of hosts:** Simple example of model of model for the energy consumption during the host boot and shutdown periods. |br| `examples/s4u/energy-boot/platform_boot.xml `_ |br| `examples/s4u/energy-boot/s4u-energy-boot.cpp `_ ======================= Tracing and Visualizing ======================= Tracing can be activated by various configuration options which are illustrated in these example. See also the :ref:`full list of options related to tracing `. It is interesting to run the process-create example with the following options to see the task executions: - **Platform Tracing:** This program is a toy example just loading the platform, so that you can play with the platform visualization. Recommanded options: ``--cfg=tracing:yes --cfg=tracing/categorized:yes`` |br| `examples/s4u/trace-platform/s4u-trace-platform.cpp `_ ======================== Larger SimGrid Examplars ======================== This section contains application examples that are somewhat larger than the previous examples. - **Ping Pong:** This simple example just sends one message back and forth. The tesh file laying in the directory show how to start the simulator binary, highlighting how to pass options to the simulators (as detailed in Section :ref:`options`). |br| `examples/s4u/app-pingpong/s4u-app-pingpong.cpp `_ - **Token ring:** Shows how to implement a classical communication pattern, where a token is exchanged along a ring to reach every participant. |br| `examples/s4u/app-token-ring/s4u-app-token-ring.cpp `_ - **Master Workers:** Another good old example, where one Master process has a bunch of task to dispatch to a set of several Worker processes. This example comes in two equivalent variants, one where the actors are specified as simple functions (which is easier to understand for newcomers) and one where the actors are specified as classes (which is more powerful for the users wanting to build their own projects upon the example). |br| `examples/s4u/app-masterworkers/s4u-app-masterworkers-class.cpp `_ |br| `examples/s4u/app-masterworkers/s4u-app-masterworkers-fun.cpp `_ Data diffusion -------------- - **Bit Torrent:** Classical protocol for Peer-to-Peer data diffusion. |br| `examples/s4u/app-bittorrent/s4u-bittorrent.cpp `_ - **Chained Send:** Data broadcast over a ring of processes. |br| `examples/s4u/app-chainsend/s4u-app-chainsend.cpp `_ Distributed Hash Tables (DHT) ----------------------------- - **Chord Protocol** One of the most famous DHT protocol. |br| `examples/s4u/dht-chord/s4u-dht-chord.cpp `_ .. TODO:: document here the examples about plugins ======================= Model-Checking Examples ======================= The model-checker can be used to exhaustively search for issues in the tested application. It must be activated at compile time, but this mode is rather experimental in SimGrid (as of v3.22). You should not enable it unless you really want to formally verify your applications: SimGrid is slower and maybe less robust when MC is enabled. - **Failing assert** In this example, two actors send some data to a central server, which asserts that the messages are always received in the same order. This is obviously wrong, and the model-checker correctly finds a counter-example to that assertion. |br| `examples/s4u/mc-failing-assert/s4u-mc-failing-assert.cpp `_ .. |br| raw:: html
.. |cpp| image:: /img/lang_cpp.png :align: middle :width: 12 .. |py| image:: /img/lang_python.png :align: middle :width: 12