# Controlling which R1 tasks run upon bootstrapping **URL:** \ **Category:** Cylc Support\ **Created:** [June 22, 2020, 7:46am UTC](https://cylc.discourse.group/t/controlling-which-r1-tasks-run-upon-bootstrapping/253 "2020-06-22T07:46:40Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![fredw](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/fredw/32/112_2.png) [@fredw](https://cylc.discourse.group/u/fredw)\ **Post date:** [June 22, 2020, 7:46am UTC](https://cylc.discourse.group/t/controlling-which-r1-tasks-run-upon-bootstrapping/253/1 "2020-06-22T07:46:40Z")
Hello all. I have a suite that runs a few tasks in R1 to prepare the suite directory. These tasks grab the source code, and compile it, so that subsequent apps will run properly. Running them in R1 makes sense as I don’t need to do it again afterwards. The tasks that require the compiled code only ever run in T00, but the suite has other things that run at T12 as well. When I start the suite on a T00 cycle point all is fine. But when I start the suite on a T12 cycle point some of those tasks in R1 also run, but shouldn’t. In fact the R1 tasks that prepare the suite for the next T00 run should run in this case, but not go any further because I haven’t started on a T00. ``` [[dependencies]] [[[R1]]] # Run once at initial cycle graph = """ install_srcs => make_engine make_engine => run_engine """ [[[T00]]] graph = """ poll_data_00 => run_engine => housekeep """ [[[T12]]] graph = """ ... """ ``` I hope I have simplified my actual suite correctly to show what’s going on. The poll\_data\_00 task is only designed to run in T00, that’s fine. But the run\_engine task should have a dependency on make\_engine, as it cannot run beforehand. How do I make sure that install\_srcs and make\_engine runs in R1 regardless of the cycle-point I start the suite on. All the while maintaining that make\_engine is finished before run\_engine ever runs? Thank you, Fred ---
**Author:** ![hilary.j.oliver](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/hilary.j.oliver/32/4_2.png) [@hilary.j.oliver](https://cylc.discourse.group/u/hilary.j.oliver)\ **Post date:** [June 22, 2020, 11:08am UTC](https://cylc.discourse.group/t/controlling-which-r1-tasks-run-upon-bootstrapping/253/2 "2020-06-22T11:08:03Z")
Hi Fred, > But when I start the suite on a T12 cycle point some of those tasks in R1 also run, but shouldn’t. As you’ve written the graph above all of your R1 tasks **should** run in the initial cycle point, no matter what it is, because R1 is short for `R1/^/` which means “run once at the initial cycle point”. If you need to be able to start on T00 or T12 cycle points, but your start-up tasks only matter for T00 tasks, then the easiest fix would be (I think) change `R1` to `R1/T00` which means run once at the first T00 point at or beyond the initial cycle point. Hilary ---
**Author:** ![oliver.sanders](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/oliver.sanders/32/110_2.png) [@oliver.sanders](https://cylc.discourse.group/u/oliver.sanders)\ **Post date:** [June 22, 2020, 12:26pm UTC](https://cylc.discourse.group/t/controlling-which-r1-tasks-run-upon-bootstrapping/253/3 "2020-06-22T12:26:03Z")
By the way there is also the related `min()` syntax which might be relevant: ```auto min(T00, T12) # the first incidence of T00 or T12 after the initial cycle point ``` [https://cylc.github.io/doc/built-sphinx-single/index.html#advanced-examples](https://cylc.github.io/doc/built-sphinx-single/index.html#advanced-examples) ---
**Author:** ![hilary.j.oliver](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/hilary.j.oliver/32/4_2.png) [@hilary.j.oliver](https://cylc.discourse.group/u/hilary.j.oliver)\ **Post date:** [June 22, 2020, 10:12pm UTC](https://cylc.discourse.group/t/controlling-which-r1-tasks-run-upon-bootstrapping/253/4 "2020-06-22T22:12:49Z")
Something else to note about your workflow: the graph says that `run_engine` only has to wait on `make_engine` in the first cycle, and not in subsequent cycles. With Cylc 7 it should work as you intend despite that, with start-up tasks in `R1/T00`, but only: - If the next `run_engine` is delayed waiting for real-time data (guessing that’s what `poll_data_00` does) - which won’t have any effect if you run behind the clock - And because Cylc-7 (and earlier) tasks implicitly depend on their own previous-instance submitting (which allows successive instances of the same task to run concurrently but not out-of-order) - this implicit constraint will be removed in Cylc 8 So in Cylc 8 you’ll find (if you start this suite far enough behind the clock that `poll_data_00` does not provide an constraint on upcoming cycles) that upcoming `run_engine`s try to execute before the initial `make_engine` is finished. Best to make the true dependencies of the system explicit like this: ```auto [[[T00]]] graph = "poll_data_00 & make_engine[^] => run_engine => housekeep" ``` or else explicitly constrain successive instances of `run_engine` execute in order (so the second one can’t run before first, which can’t run before `make_engine` is done, …), e.g.: ```auto [[[T00]]] graph = """poll_data_00 => run_engine => housekeep run_engine[-P1D]:submit => run_engine""" ``` ---
**Author:** ![fredw](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/fredw/32/112_2.png) [@fredw](https://cylc.discourse.group/u/fredw)\ **Post date:** [July 5, 2020, 7:16am UTC](https://cylc.discourse.group/t/controlling-which-r1-tasks-run-upon-bootstrapping/253/5 "2020-07-05T07:16:22Z")
Thank you Hilary, and sorry for not replying sooner. I got side-tracked onto another project and only today managed to return to this problem. First I looked at your suggestion using the `R1/T00` syntax (which I didn’t know about). I split the R1 block into 2 sections, one `[[[R1]]]` and another `[[[R1/T00]]]`. This prevents `run_engine` from running on an initial T12 cycle point. In that case the suite simply runs `install_srcs` and `make_engine`, but not `run_engine` (which doesn’t need to run until the next T00 cycle point). ``` [[dependencies]] [[[R1]]] # Run once at initial cycle (at any time point T00 and T12) graph = """ install_srcs => make_engine """ [[[R1/T00]]] # Run once at initial cycle (only at time point T00) graph = """ make_engine => run_engine """ [[[T00]]] graph = """ poll_data_00 => run_engine => housekeep """ [[[T12]]] graph = """ ... """ ``` Looking at the resulting bubble graph, I also noticed that there could be a timing issue, as you pointed out in your later reply. The `run_engine` task in the subsequent T00 cycle point could run before, the `install_srcs => make_engine` is finished in the initial T12 cycle point. So I experimented with your other suggestions (using the `[^]` syntax I wasn’t familiar with): ``` [[dependencies]] [[[R1]]] # Run once at initial cycle (at any time point T00 and T12) graph = """ install_srcs => make_engine """ [[[R1/T00]]] # Run once at initial cycle (only at time point T00) graph = """ make_engine[^] => run_engine """ ``` The extra `[^]` worked. There was now a dependency from **run\_engine** in the T00 cycle point back to `make_engine` in the initial T12 cycle point. **But I don’t understand why this worked at all - the suite was started on a T12 cycle point, so why is `R1/T00` intepreted at all?** I also used the other suggestion of using inter-cycle dependencies: ``` [[[T00]]] graph = """ run_engine[-P1D] => run_engine """ ``` but as you say in cylc 7 it doesn’t cause any different behaviour. but I left it in as it makes the resulting behaviour more explicit. As always many thanks for your help!! Very much appreciated Fred ---
**Author:** ![hilary.j.oliver](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/hilary.j.oliver/32/4_2.png) [@hilary.j.oliver](https://cylc.discourse.group/u/hilary.j.oliver)\ **Post date:** [July 6, 2020, 5:21am UTC](https://cylc.discourse.group/t/controlling-which-r1-tasks-run-upon-bootstrapping/253/6 "2020-07-06T05:21:35Z")
> [@fredw](#): > > But I don’t understand why this worked at all - the suite was started on a T12 cycle point, so why is `R1/T00` intepreted at all? Your code comments suggest you’ve misunderstood the meaning of `R1` and `R1/T00` slightly. This comment is correct: ```auto [[[R1]]] # Run once at initial cycle (at any time point T00 and T12) [OK] ``` But this one: ```auto [[[R1/T00]]] # Run once at initial cycle (only at time point T00) [WRONG] ``` should read: ```auto [[[R1/T00]]] # Run once at the first T00 cycle (which may or may not be the initial cycle point!) ``` Does that explain why “`R1/T00` is interpreted at all”? Hilary p.s. `R1` by itself means “run once **at the initial cycle point** ” because `R1/^` is inferred if a specific point is not given ---
**Author:** ![fredw](https://yyz2.discourse-cdn.com/free1/user_avatar/cylc.discourse.group/fredw/32/112_2.png) [@fredw](https://cylc.discourse.group/u/fredw)\ **Post date:** [July 6, 2020, 6:05am UTC](https://cylc.discourse.group/t/controlling-which-r1-tasks-run-upon-bootstrapping/253/7 "2020-07-06T06:05:01Z")
Now I get it. Thanks for the explanation. I’ll change the comments in my suite