Logo AND Algorithmique Numérique Distribuée

Public GIT Repository
New signal: Actor::on_termination (when its code terminates)
[simgrid.git] / examples / s4u / README.rst
1 .. S4U (Simgrid for you) is the next interface of SimGrid, expected to be released with SimGrid 4.0.
2 ..
3 .. Even if it is not completely rock stable yet, it may well already fit
4 .. your needs. You are welcome to try it and report any interface
5 .. glitches that you see. Be however warned that the interface may change
6 .. until the final release.  You will have to adapt your code on the way.
7 .. 
8 .. This file follows the ReStructured syntax to be included in the
9 .. documentation, but it should remain readable directly.
10
11
12 S4U Examples
13 ************
14
15 SimGrid comes with an extensive set of examples, documented on this
16 page. Most of them only demonstrate one single feature, with some
17 larger examplars listed below. 
18
19 The C++ examples can be found under examples/s4u while python examples
20 are in examples/python. Each such directory contains the source code (also listed
21 from this page), and the so-called tesh file containing how to call
22 the binary obtained by compiling this example and also the expected
23 output. Tesh files are used to turn each of our examples into an
24 integration test. Some examples also contain other files, on need.
25
26 A good way to bootstrap your own project is to copy and combine some
27 of the provided examples to constitute the skeleton of what you plan
28 to simulate.
29
30 ===========================
31 Actors: the Active Entities
32 ===========================
33
34 .. _s4u_ex_actors:
35
36 Starting and Stoping Actors
37 ---------------------------
38
39   - **Creating actors:**
40     Most actors are started from the deployment XML file, but there is other methods.
41     This example show them all.
42     `examples/python/actor-create/actor-create_d.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-create/actor-create_d.xml>`_
43     
44     - |cpp| `examples/s4u/actor-create/s4u-actor-create.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-create/s4u-actor-create.cpp>`_
45     - |py|  `examples/python/actor-create/actor-create.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-create/actor-create.py>`_
46
47   - **React to the end of actors:**
48     You can attach a callback to the end of actors. There is two ways
49     of doing so, depending of whether you want your callback to be
50     executed when a specific actor ends (with ```this_actor::on_exit()```)
51     or whether it should be executed when any actor ends (with
52     ```Actor::on_termination()```) or when it gets destroyed (with
53     ```Actor::on_destruction()```)
54
55     - |cpp| `examples/s4u/actor-exiting/s4u-actor-exiting.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-exiting/s4u-actor-exiting.cpp>`_
56
57   - **Kill actors:**
58     Actors can forcefully stop other actors.
59     
60     - |cpp| `examples/s4u/actor-kill/s4u-actor-kill.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-kill/s4u-actor-kill.cpp>`_
61       :cpp:func:`void simgrid::s4u::Actor::kill(void)`,
62       :cpp:func:`void simgrid::s4u::Actor::kill_all()`,
63       :cpp:func:`simgrid::s4u::this_actor::exit`.
64     - |py| `examples/python/actor-kill/actor-kill.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-kill/actor-kill.py>`_
65       :py:func:`simgrid.Actor.kill`,
66       :py:func:`simgrid.Actor.kill_all`, 
67       :py:func:`simgrid.this_actor.exit`.
68
69   - **Controling the actor life cycle from the XML:**
70     You can specify a start time and a kill time in the deployment
71     file.
72     |br| `examples/s4u/actor-lifetime/s4u-actor-lifetime.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-lifetime/s4u-actor-lifetime.cpp>`_
73     |br| `examples/s4u/actor-lifetime/s4u-actor-lifetime_d.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-lifetime/s4u-actor-lifetime_d.xml>`_
74
75   - **Daemonize actors:**
76     Some actors may be intended to simulate daemons that run in background. This example show how to transform a regular
77     actor into a daemon that will be automatically killed once the simulation is over.
78     
79     - |cpp| `examples/s4u/actor-daemon/s4u-actor-daemon.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-daemon/s4u-actor-daemon.cpp>`_
80     - |py|  `examples/python/actor-daemon/actor-daemon.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-daemon/actor-daemon.py>`_
81     
82 Inter-Actors Interactions
83 -------------------------
84
85 See also the examples on :ref:`inter-actors communications
86 <s4u_ex_communication>` and the ones on :ref:`classical
87 synchronization objects <s4u_ex_IPC>`.
88
89   - **Suspend and Resume actors:**    
90     Actors can be suspended and resumed during their executions.
91     
92     - |cpp| `examples/s4u/actor-suspend/s4u-actor-suspend.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-suspend/s4u-actor-suspend.cpp>`_
93       :cpp:func:`simgrid::s4u::this_actor::suspend()`,
94       :cpp:func:`simgrid::s4u::Actor::suspend()`, :cpp:func:`simgrid::s4u::Actor::resume()`, :cpp:func:`simgrid::s4u::Actor::is_suspended()`.
95     - |py|  `examples/python/actor-suspend/actor-suspend.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-suspend/actor-suspend.py>`_
96       :py:func:`simgrid.this_actor.suspend()`,
97       :py:func:`simgrid.Actor.suspend()`, :py:func:`simgrid.Actor.resume()`, :py:func:`simgrid.Actor.is_suspended()`.
98
99   - **Migrating Actors:**
100     Actors can move or be moved from a host to another very easily.
101     
102     - |cpp| `examples/s4u/actor-migrate/s4u-actor-migrate.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-migrate/s4u-actor-migrate.cpp>`_
103       :cpp:func:`simgrid::s4u::this_actor::migrate()`
104     - |py|  `examples/python/actor-migrate/actor-migrate.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-migrate/actor-migrate.py>`_
105       :py:func:`simgrid.this_actor.migrate()`
106
107   - **Waiting for the termination of an actor:** (joining on it)
108     You can block the current actor until the end of another actor.
109     
110     - |cpp| `examples/s4u/actor-join/s4u-actor-join.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-join/s4u-actor-join.cpp>`_
111       :cpp:func:`simgrid::s4u::Actor::join()`
112     - |py|  `examples/python/actor-join/actor-join.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-join/actor-join.py>`_
113       :py:func:`simgrid.Actor.join()`
114
115   - **Yielding to other actors**.
116     The ```yield()``` function interrupts the execution of the current
117     actor, leaving a chance to the other actors that are ready to run
118     at this timestamp.
119     
120     - |cpp| `examples/s4u/actor-yield/s4u-actor-yield.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/actor-yield/s4u-actor-yield.cpp>`_
121       :cpp:func:`simgrid::s4u::this_actor::yield()`
122     - |py|  `examples/python/actor-yield/actor-yield.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/actor-yield/actor-yield.py>`_
123       :py:func:`simgrid.this_actor.yield_()`
124
125 Traces Replay as a Workload
126 ---------------------------
127
128 This section details how to run trace-driven simulations. It is very
129 handy when you want to test an algorithm or protocol that only react
130 to external events. For example, many P2P protocols react to user
131 requests, but do nothing if there is no such event.
132
133 In such situations, you should write your protocol in C++, and separate
134 the workload that you want to play onto your protocol in a separate
135 text file. Declare a function handling each type of the events in your
136 trace, register them using :cpp:func:`xbt_replay_action_register()` in
137 your main, and then run the simulation.
138
139 Then, you can either have one trace file containing all your events,
140 or a file per simulated process: the former may be easier to work
141 with, but the second is more efficient on very large traces. Check
142 also the tesh files in the example directories for details.
143
144   - **Communication replay:**
145     Presents a set of event handlers reproducing classical communication
146     primitives (asynchronous send/receive at the moment).
147     |br| `examples/s4u/replay-comm/s4u-replay-comm.cpp  <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/replay-comm/s4u-replay-comm.cpp>`_
148
149   - **I/O replay:**
150     Presents a set of event handlers reproducing classical I/O
151     primitives (open, read, close).
152     |br| `examples/s4u/replay-storage/s4u-replay-storage.cpp  <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/replay-storage/s4u-replay-storage.cpp>`_
153
154 ==========================
155 Activities: what Actors do
156 ==========================
157
158 .. _s4u_ex_communication:
159
160 Communications on the Network
161 -----------------------------
162
163  - **Basic asynchronous communications:**
164    Illustrates how to have non-blocking communications, that are
165    communications running in the background leaving the process free
166    to do something else during their completion. 
167    
168    - |cpp| `examples/s4u/async-wait/s4u-async-wait.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/async-wait/s4u-async-wait.cpp>`_
169      :cpp:func:`simgrid::s4u::Mailbox::put_async()` and :cpp:func:`simgrid::s4u::Comm::wait()`
170    - |py|  `examples/python/async-wait/async-wait.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/async-wait/async-wait.py>`_
171      :py:func:`simgrid.Mailbox.put_async()` :py:func:`simgrid.Comm.wait()`
172
173  - **Waiting for all communications in a set:**
174    The `wait_all()` function is useful when you want to block until
175    all activities in a given set have completed. 
176    
177    - |cpp| `examples/s4u/async-waitall/s4u-async-waitall.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/async-waitall/s4u-async-waitall.cpp>`_
178      :cpp:func:`simgrid::s4u::Comm::wait_all()`
179    - |py| `examples/python/async-waitall/async-waitall.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/async-waitall/async-waitall.py>`_
180      :py:func:`simgrid.Comm.wait_all()`
181
182  - **Waiting for the first completed communication in a set:**
183    The `wait_any()` function is useful
184    when you want to block until one activity of the set completes, no
185    matter which terminates first.
186    
187    - |cpp| `examples/s4u/async-waitany/s4u-async-waitany.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/async-waitany/s4u-async-waitany.cpp>`_
188      :cpp:func:`simgrid::s4u::Comm::wait_any()`
189    - |py| `examples/python/async-waitany/async-waitany.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/async-waitany/async-waitany.py>`_
190      :py:func:`simgrid.Comm.wait_any()`
191      
192 .. todo:: review the `ready` and `waituntil` examples and add them here.
193    
194 .. _s4u_ex_execution:
195
196 Executions on the CPU
197 ---------------------
198
199   - **Basic execution:**
200     The computations done in your program are not reported to the
201     simulated world, unless you explicitely request the simulator to pause
202     the actor until a given amount of flops gets computed on its simulated
203     host. Some executions can be given an higher priority so that they
204     get more resources.
205     
206     - |cpp| `examples/s4u/exec-basic/s4u-exec-basic.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-basic/s4u-exec-basic.cpp>`_
207     - |py|  `examples/python/exec-basic/exec-basic.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/exec-basic/exec-basic.py>`_
208
209   - **Asynchronous execution:**
210     You can start asynchronous executions, just like you would fire
211     background threads.
212     
213     - |cpp| `examples/s4u/exec-async/s4u-exec-async.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-async/s4u-exec-async.cpp>`_
214     - |py|  `examples/python/exec-async/exec-async.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/exec-async/exec-async.py>`_
215     
216   - **Remote execution:**
217     You can start executions on remote hosts, or even change the host
218     on which they occur during their execution.
219     
220     - |cpp| `examples/s4u/exec-remote/s4u-exec-remote.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-remote/s4u-exec-remote.cpp>`_
221     - |py| `examples/python/exec-remote/exec-remote.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/exec-remote/exec-remote.py>`_
222
223   - **Parallel executions:**
224     These objects are convenient abstractions of parallel
225     computational kernels that span over several machines, such as a
226     PDGEM and the other ScaLAPACK routines. Note that this only works
227     with the "ptask_L07" host model (``--cfg=host/model:ptask_L07``).
228     |br| `examples/s4u/exec-ptask/s4u-exec-ptask.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-ptask/s4u-exec-ptask.cpp>`_
229     
230   - **Using Pstates on a host:**
231     `examples/platforms/energy_platform.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/energy_platform.xml>`_
232     shows how define a set of pstates in the XML. The current pstate
233     of an host can then be accessed and changed from the program.
234
235     - |cpp| `examples/s4u/exec-dvfs/s4u-exec-dvfs.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/exec-dvfs/s4u-exec-dvfs.cpp>`_
236       :cpp:func:`simgrid::s4u::Host::get_pstate_speed` and :cpp:func:`simgrid::s4u::Host::set_pstate`.
237     - |py|  `examples/python/exec-dvfs/exec-dvfs.py <https://framagit.org/simgrid/simgrid/tree/master/examples/python/exec-dvfs/exec-dvfs.py>`_
238       :py:func:`Host.get_pstate_speed` and :py:func:`Host.set_pstate`.
239
240 I/O on Disks and Files
241 ----------------------
242
243 SimGrid provides two levels of abstraction to interact with the
244 simulated storages. At the simplest level, you simply create read and
245 write actions on the storage resources.
246
247   - **Access to raw storage devices:**
248     This example illustrates how to simply read and write data on a
249     simulated storage resource.
250     |br| `examples/s4u/io-storage-raw/s4u-io-storage-raw.cpp  <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/io-storage-raw/s4u-io-storage-raw.cpp>`_
251
252 The FileSystem plugin provides a more detailed view, with the
253 classical operations over files: open, move, unlink, and of course
254 read and write. The file and disk sizes are also dealt with and can
255 result in short reads and short write, as in reality.
256
257   - **File Management:**
258     This example illustrates the use of operations on files
259     (read, write, seek, tell, unlink, etc).
260     |br| `examples/s4u/io-file-system/s4u-io-file-system.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/io-file-system/s4u-io-file-system.cpp>`_
261
262   - **Remote I/O:**
263     I/O operations on files can also be done in a remote fashion, 
264     i.e. when the accessed disk is not mounted on the caller's host.
265     |br| `examples/s4u/io-file-remote/s4u-io-file-remote.cpp  <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/io-file-remote/s4u-io-file-remote.cpp>`_
266
267 .. _s4u_ex_IPC:
268
269 Classical synchronization objects
270 ---------------------------------
271
272  - **Mutex:**
273    Shows how to use simgrid::s4u::Mutex synchronization objects.
274    |br| `examples/s4u/synchro-mutex/s4u-synchro-mutex.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/synchro-mutex/s4u-synchro-mutex.cpp>`_
275
276  - **Barrier:**
277    Shows how to use simgrid::s4u::Barrier synchronization objects.
278    |br| `examples/s4u/synchro-barrier/s4u-synchro-barrier.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/synchro-barrier/s4u-synchro-barrier.cpp>`_
279
280  - **Semaphore:**
281    Shows how to use simgrid::s4u::Semaphore synchronization objects.
282    |br| `examples/s4u/synchro-semaphore/s4u-synchro-semaphore.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/synchro-semaphore/s4u-synchro-semaphore.cpp>`_
283
284 =============================
285 Interacting with the Platform
286 =============================
287
288  - **Retrieving the list of hosts matching a given criteria:**
289    Shows how to filter the actors that match a given criteria.
290    |br| `examples/s4u/engine-filtering/s4u-engine-filtering.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/engine-filtering/s4u-engine-filtering.cpp>`_
291
292  - **User-defined properties:**
293    You can attach arbitrary information to most platform elements from
294    the XML file, and then interact with these values from your
295    program. Note that the changes are not written permanently on disk,
296    in the XML file nor anywhere else. They only last until the end of
297    your simulation.
298    
299    - :cpp:func:`simgrid::s4u::Actor::get_property()` and :cpp:func:`simgrid::s4u::Actor::set_property()`
300    - :cpp:func:`simgrid::s4u::Host::get_property()` and :cpp:func:`simgrid::s4u::Host::set_property()`
301    - :cpp:func:`simgrid::s4u::Link::get_property()` and :cpp:func:`simgrid::s4u::Link::set_property()`
302    - :cpp:func:`simgrid::s4u::NetZone::get_property()` and :cpp:func:`simgrid::s4u::NetZone::set_property()`
303      
304    |br| `examples/s4u/platform-properties/s4u-platform-properties.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/platform-properties/s4u-platform-properties.cpp>`_
305    |br| `examples/s4u/platform-properties/s4u-platform-properties_d.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/platform-properties/s4u-platform-properties_d.xml>`_
306    |br| `examples/platforms/prop.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/prop.xml>`_
307
308  - **Specifying state profiles:** shows how to specify when the
309    resources must be turned off and on again, and how to react to such
310    failures in your code.
311    
312    |br| `examples/platforms/small_platform_failures.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/small_platform_failures.xml>`_
313    |br| The state profiles in `examples/platforms/profiles <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/profiles>`_
314
315  - **Specifying speed profiles:** shows how to specify an external
316    load to resources, variating their peak speed over time.
317    
318    |br| `examples/platforms/small_platform_profile.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/small_platform_profile.xml>`_
319    |br| The speed, bandwidth and latency profiles in `examples/platforms/profiles  <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/profiles>`_
320
321 =================
322 Energy Simulation
323 =================
324
325   - **Describing the energy profiles in the platform:**
326     This platform file contains the energy profile of each links and
327     hosts, which is necessary to get energy consumption predictions.
328     As usual, you should not trust our example, and you should strive
329     to double-check that your instanciation matches your target platform.
330     |br| `examples/platforms/energy_platform.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/platforms/energy_platform.xml>`_
331
332   - **Consumption due to the CPU:** 
333     This example shows how to retrieve the amount of energy consumed
334     by the CPU during computations, and the impact of the pstate.
335     |br| `examples/s4u/energy-exec/s4u-energy-exec.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-exec/s4u-energy-exec.cpp>`_
336
337   - **Consumption due to the network:**
338     This example shows how to retrieve and display the energy consumed
339     by the network during communications.
340     |br| `examples/s4u/energy-link/s4u-energy-link.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-link/s4u-energy-link.cpp>`_
341
342   - **Modeling the shutdown and boot of hosts:**
343     Simple example of model of model for the energy consumption during
344     the host boot and shutdown periods.
345     |br| `examples/s4u/energy-boot/platform_boot.xml <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-boot/platform_boot.xml>`_
346     |br| `examples/s4u/energy-boot/s4u-energy-boot.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/energy-boot/s4u-energy-boot.cpp>`_
347
348 =======================
349 Tracing and Visualizing
350 =======================
351
352 Tracing can be activated by various configuration options which
353 are illustrated in these example. See also the 
354 :ref:`full list of options related to tracing <tracing_tracing_options>`.
355
356 It is interesting to run the process-create example with the following
357 options to see the task executions:
358
359   - **Platform Tracing:**
360     This program is a toy example just loading the platform, so that
361     you can play with the platform visualization. Recommanded options:
362     ``--cfg=tracing:yes --cfg=tracing/categorized:yes``
363     |br| `examples/s4u/trace-platform/s4u-trace-platform.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/trace-platform/s4u-trace-platform.cpp>`_
364
365 ========================
366 Larger SimGrid Examplars
367 ========================
368
369 This section contains application examples that are somewhat larger
370 than the previous examples.
371
372   - **Ping Pong:**
373     This simple example just sends one message back and forth.
374     The tesh file laying in the directory show how to start the simulator binary, highlighting how to pass options to 
375     the simulators (as detailed in Section :ref:`options`). 
376     |br| `examples/s4u/app-pingpong/s4u-app-pingpong.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-pingpong/s4u-app-pingpong.cpp>`_
377
378   - **Token ring:**
379     Shows how to implement a classical communication pattern, where a
380     token is exchanged along a ring to reach every participant.
381     |br| `examples/s4u/app-token-ring/s4u-app-token-ring.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-token-ring/s4u-app-token-ring.cpp>`_
382
383   - **Master Workers:**
384     Another good old example, where one Master process has a bunch of task to dispatch to a set of several Worker 
385     processes. This example comes in two equivalent variants, one
386     where the actors are specified as simple functions (which is easier to
387     understand for newcomers) and one where the actors are specified
388     as classes (which is more powerful for the users wanting to build
389     their own projects upon the example).
390     |br| `examples/s4u/app-masterworkers/s4u-app-masterworkers-class.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-masterworkers/s4u-app-masterworkers-class.cpp>`_
391     |br| `examples/s4u/app-masterworkers/s4u-app-masterworkers-fun.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-masterworkers/s4u-app-masterworkers-fun.cpp>`_
392     
393 Data diffusion
394 --------------
395
396   - **Bit Torrent:** 
397     Classical protocol for Peer-to-Peer data diffusion.
398     |br| `examples/s4u/app-bittorrent/s4u-bittorrent.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-bittorrent/s4u-bittorrent.cpp>`_
399     
400   - **Chained Send:** 
401     Data broadcast over a ring of processes.
402     |br| `examples/s4u/app-chainsend/s4u-app-chainsend.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/app-chainsend/s4u-app-chainsend.cpp>`_
403
404 Distributed Hash Tables (DHT)
405 -----------------------------
406
407   - **Chord Protocol** 
408     One of the most famous DHT protocol.
409     |br| `examples/s4u/dht-chord/s4u-dht-chord.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/dht-chord/s4u-dht-chord.cpp>`_
410
411 .. _s4u_ex_clouds:
412
413 Simulating Clouds
414 -----------------
415
416   - **Cloud basics**
417     This example starts some computations both on PMs and VMs, and
418     migrates some VMs around.
419     |br| `examples/s4u/cloud-simple/s4u-cloud-simple.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/cloud-simple/s4u-cloud-simple.cpp>`_
420
421 .. TODO:: document here the examples about clouds and plugins
422
423 =======================
424 Model-Checking Examples
425 =======================
426
427 The model-checker can be used to exhaustively search for issues in the
428 tested application. It must be activated at compile time, but this
429 mode is rather experimental in SimGrid (as of v3.22). You should not
430 enable it unless you really want to formally verify your applications:
431 SimGrid is slower and maybe less robust when MC is enabled.
432
433   - **Failing assert**
434     In this example, two actors send some data to a central server,
435     which asserts that the messages are always received in the same order.
436     This is obviously wrong, and the model-checker correctly finds a
437     counter-example to that assertion.
438     |br| `examples/s4u/mc-failing-assert/s4u-mc-failing-assert.cpp <https://framagit.org/simgrid/simgrid/tree/master/examples/s4u/mc-failing-assert/s4u-mc-failing-assert.cpp>`_
439
440 .. |br| raw:: html
441
442    <br />
443
444 .. |cpp| image:: /img/lang_cpp.png
445    :align: middle
446    :width: 12
447
448 .. |py| image:: /img/lang_python.png
449    :align: middle
450    :width: 12