Hi Patrick, Thanks for taking on this endeavor, and apologies for the suffering you must have endured in dealing with this code.
If I followed your instructions correctly, it looks like things are very close to working. One feature that seems to be broken is the storing of references to special top-level signals (which perform actions like redrawing animations or updating snips) to protect them from the garbage collector. It's been a while since I've looked at this code, but I'll try to investigate a bit more and see what might be going wrong. Cheers, Greg On Fri, Aug 17, 2012 at 12:51 PM, Patrick Mahoney <[email protected]> wrote: > Hello All, > > I have been working on updating the frtime collection to use the Racket lang > rather than the mzscheme language. To this end, I forked on github and > created a new branch frtime-to-racket, which can be found at: > https://github.com/paddymahoney/racket.git > > This branch contains 36 commits. The first 34 are minor, and don't actually > break functionality. See the commit log: > https://github.com/paddymahoney/racket/commits/frtime-to-racket > > The 35th commit is bigger, and represents the bulk of the move of the > collection and the other main modules to the racket lang rather than > mzscheme. The issue I face is that this commit is breaking all of the demos > within the frtime/demos/ subdirectory. These demos rely on animation.rkt at > the root. The demos in the frtime/gui/demo directory don't depend on > animation.rkt, and seem to work, albeit with a slow asynchronous perhaps? > (perhaps some subset of the issues affecting the animation demos also affect > the demos relying only on the fred wrappers). > > The 36th commit is a new helper "develop-frtime.rkt" which I use to unlink > the install collection and link the development frtime collection. > > I have very closely reviewed all the changes in the commit logs, and have > played around extensively to try to find a particular change that has the > effect of breaking the animations, to no avail. > > My uneducated guesses as to what is occurring: > 1. The behavior seen in running the demos is that they will typically > update for a few frames or seconds, but then freeze in place. A similar > issue is described in Gregory Cooper's thesis "Integrating Dataflow > Evaluation into a Practical > Higher-Order Call-by-Value Language". From page 99: > "There is, however, a problem with the strategy described above that is > difficult to di-agnose and debug. The symptoms are as follows: at first, the > program seems to work just > fine. Sometimes it may run successfully to completion. Other times, > depending upon what > else is happening, it runs for a while, then suddenly and seemingly without > explanation the > gauge’s properties stop updating when the behaviors change. The point at > which it stops > varies from run to run, but there are never any error messages. > The problem results from an interaction with the memory manager. An ordinary > FRP > application would use the event source returned by the map-e, but in this > case we only > care about side effects, so we neglect to save the result. Since there are > no references to > the updating event source, the garbage collector eventually reclaims it, and > the gauge stops > reacting to changes in the behavior. > To avoid these problems, we define a new abstraction specifically for > side-effecting > event processors. This abstraction, called for-each-e!, works just like > map-e, except that it > ensures its result will not be collected. It also lends itself to a more > efficient implementa-tion, since it can throw away the results of the > procedure calls instead of enqueuing them > on a new event stream." > >> this seems very much like what I see in the behavior of say, >> "demos/analog-clock.rkt". You are often able to force an update by dragging >> the clock or updating the slider, and occasionally the clock will tick in >> the beginning. In addition, sometimes the clock won't show initially (this >> may occur when there is a difference in the way the dataflow graph is >> updated?). However, I have been unsuccessful in determining whether this is >> in fact the case, or if there a distinct issue here with similar symptoms. >> In fact, I don't know what is occurring at all, and I am at a loss as to how >> to resolve this problem. > > 2. Something isn't being lifted. >> I have run Check Syntax and traced most of the bindings to ensure that >> lifted equivalents are being used everywhere. I can't find a binding that >> was not lifted, but I cannot rule this out either. >>Files that might be involved: > lang-utils.rkt > lang-core.rkt > opt/frtime-opt-lang.rkt > > 3. Persuant to 1, garbage collection behavior/calls have changed, and the > result is that some behavior is being collected prematurely. Interactions > with mred usage and garbage collection might contribute if this is an issue. > > I have invested a ton of time into understanding enough to make even these > minor changes, and really don't want to see this work die on the vine. So I > open it to you Racket experts for help debugging this. > > Instructions to see the issue: > Open a command line and: >> git clone https://github.com/paddymahoney/racket.git > (you might want to do this in a different directory than that which holds > another fork of racket) >>git checkout frtime-to-racket > Open the "racket/collects/frtime/develop-frtime.rkt" file in drracket and > update the two paths. Run the function (start-developing-frtime) to ensure > that the development rather than installation collection is used when we run > the demos. If you don't, any collection paths will refer to the install > directory, and you will receive errors. > Open "racket/collects/frtime/demos/analog-clock.rkt. Run it. > > Please let me know if you require any further assistance reproducing this > bug, and I will endeavor to provide. In addition, I will be extremely > grateful for any assistance here. I'd like to attend the October RacketConf, > and a beverage of some kind would be in order to reward my hero. > > Thank you all, > > -Patrick > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users > ____________________ Racket Users list: http://lists.racket-lang.org/users
