I'm using Flutter and need to do some parsing. To prevent said parsing from blocking the UI, I'm using an Isolate ; however spawning the Isolate seems to have a big time cost (~2s on my Samsung A5, with the 'compute' fonction). Which is a bit stupid, since the parsing takes less time then that...
Since I don't want my users to have to wait for 2 seconds 'for free', I'd like to launch an Isolate when the app starts, and just give it the parsing to do when I need to do it.
What is the best way to accomplish this in Dart ? There's probably something better to do then a while(true) loop...
Thanks.
Can you try using the easy_isolate plugin? I tried here and took only 195ms to execute a code inside the isolate.
The Parallel.run works like the compute function. The plugin has well-explained documentation.
https://pub.dev/packages/easy_isolate
Related
I'm new to Anylogic and created a simple traffic model. Only use 'carSource', 'CarMoveTo', 'Car Dispose' blocks to set the car routes. But After I ran the model, it worked for a while, then all the cars froze without any error occurring. ’Events‘ panel also stopped. How to solve it?
Most likely your model is running into an infinite loop somewhere in the logic. The first place to check would be all your loops that might become infinite,e.g Do loops, Do-while loops, iterator for loops where you perhaps change the counter variable manually...
If you have the professional version of AnyLogic the best option is to run the model in debug mode until you get this to the point where it freezes and then press pause. You will then see where in the code the model is getting stuck.
If this does not work you might need to start putting traceln in major functions and see ing you can spot the last traceln that gets printed and keep on adding more and more until you can find the point between two traceln where the model freezes
I had the same problem, that after a certain time, all cars froze and there wasn't a signle error.
The problem on my side was that the stop line was too close to the intersection, so I moved it a little bit farther.
If I have a function call that returns true or false as the condition of an if statement, do I have to worry about Swift forking my code for efficiency?
For example,
if (resourceIsAvailable()) { //execute code }
If checking for the resource is computationally expensive, will Xcode wait or attempt to continue on with the code?
Is this worth using a completion handler?
What if the resource check must make a database call?
Good question.
First off... can a function be used? Absolutely.
Second... should it be used?
A lot of that depends on the implementation of the function. If the function is known (to the person who wrote it) to take a long time to complete then I would expect that person to deal with that accordingly.
Thankfully with a lot of iOS things like that are taken out of the hands of the developer (mostly). CoreData and Network requests normally come with a completion handler. So any function that uses them would also need to be async and have a completion handler.
There is no fixed rule for this. My best advice would be...
If you can see the implementation of the function then try to work out what it’s doing.
If you can’t then give it a go. You could even use the time profiler in Xcode profiler to determine how long it is taking to complete.
The worst that could happen is you find it is slow and then change it for something else.
I'm fairly new to using Google Docs, but I have come to really appreciate it. The scripting is pretty easy to accomplish simple tasks, but I have come to realize a potential speed issue that is a little frustrating.
I've got a sheet that I use for my business to calculate the cost of certain materials on a jobsite. It works great, but was a little tedious to clear between jobs so I wrote a simple script to clear the ranges (defined by me and referenced by name) that I needed emptied.
Once again, worked great. The only problem with it is that clearing a few ranges (seven) ends up taking about ten full seconds. I -believe- that this is because the spreadsheet is being saved after each range is cleared, which becomes time intensive.
What I'd like to do is test this theory by disabling autosave in the script, and then re enabling it after the ranges have been cleared. I don't know if this is even possible because I haven't seen a function in the API to do it, but if it is I'd love to know about it.
Edit: this is the function I'm using as it stands. I've tried rewriting it a couple of times to be more concise and less API call intensive, but so far I haven't had any luck in reducing the time it takes to process the calls.
function clearSheet() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getActiveSheet();
sheet.getRange("client").clear();
sheet.getRange("lm_group_1").clear({contentsOnly:true});
sheet.getRange("lm_group_2").clear({contentsOnly:true});
sheet.getRange("dr_group_1").clear({contentsOnly:true});
sheet.getRange("dr_group_2").clear({contentsOnly:true});
sheet.getRange("fr_group_1").clear({contentsOnly:true});
sheet.getRange("fr_group_2").clear({contentsOnly:true});
sheet.getRange("gr_group_1").clear({contentsOnly:true});
sheet.getRange("client_name").activate();
}
That is not possible, and will probably never be. It's not "the nature" for Google Docs.
But depending on how you wrote your script, it's probable that all changes are already being wrote at once, in the end. There's some API calls that may be forcing a flush of your writings to the spreadsheet (like trying to read after you wrote something), but we'd need to see your code to check that.
Anyway, you can always check the spreadsheet revision history to verify if it's being done at once or in multiple steps.
About the performance, Apps Scripts have a natural delay that is unavoidable, but it's not 10s, so there's probably room to improve on your script, using fewer API calls and preferring batch calls like setValues over setValue and so on. But then again, we'd have to see your code to assert that and give more helpful tips.
I have split my module with GWT.RunAsync to load faster for the first time. But once it is loaded, I want to load all other code splits as user will be idle for some time, and it will be faster for him to work on those parts when needed.
Any one have tried to do this? Any simple way of doing?
You can call GWT.RunAsync with a callback function that may or may not run the newly-loaded code. In the case where the code isnt' run, the callback turns into a no-op... with the handy side-effect of loading the rest of the code.
See "prefetching" at http://code.google.com/webtoolkit/doc/latest/DevGuideCodeSplitting.html#patterns
I've been working on a bit of JavaScript code that, under certain conditions, lazy-loads a couple of different libraries (Clicky Web Analytics and the Sizzle selector engine).
This script is downloaded millions of times per day, so performance optimization is a major concern. To date, I've employed a couple of flags like script_loading and script_loaded to try to ensure that I don't load either library more than once (by "load," I mean requesting the scripts after page load by inserting a <script> element into the DOM).
My question is: Rather than rely on these flags, which have gotten a little unwieldy and hard to follow in my code (think callbacks and all of the pitfalls of asynchronous code), is it cross-browser safe (i.e., back to IE 6) and not detrimental to performance to just call a simple function to insert a <script> element whenever I reach a code branch that needs one of these libraries?
The latter would still ensure that I only load either library when I need it, and would also simplify and reduce the weight of my code base, but I need to be absolutely sure that this won't result in additional, unnecessary browser requests.
My hunch is that appending a <script> element multiple times won't be harmful, as I assume browsers should recognize a duplicate src URL and rely on a local cached copy. But, you know what happens when we assume...
I'm hoping that someone is familiar enough with the behavior of various modern (and not-so-modern, such as IE 6) browsers to be able to speak to what will happen in this case.
In the meantime, I'll write a test to try to answer this first-hand. My hesitation is just that this may be difficult and cumbersome to verify with certainty in every browser that my script is expected to support.
Thanks in advance for any help and/or input!
Got an alternative solution.
At the point where you insert the new script element in the DOM, could you not do a quick scan of existing script elements to see if there is another one with the same src? If there is, don't insert another?
Javascript code on the same page can't run multithreaded, so you won't get any race conditions in the middle of this or anything.
Otherwise you are just relying on the caching behaviour of current browsers (and HTTP proxies).
The page is processed as a stream. If you load the same script multiple times, it will be run every time it is included. Obviously, due to the browser cache, it will be requested from the server only once.
I would stay away from this approach of inserting script tags for the same script multiple times.
The way I solve this problem is to have a "test" function for every script to see if it is loaded. E.g. for sizzle this would be "function() { return !!window['Sizzle']; }". The script tag is only inserted if the test function returns false.
Each time you add a script to your page,even if it has the same src the browser may found it on the local cache or ask the server if the content is changed.
Using a variable to check if the script is included is a good way to reduce loading and it's very simple:
for example this may works for you:
var LOADED_JS=Object();
function js_isIncluded(name){//returns true if the js is already loaded
return LOADED_JS[name]!==undefined;
}
function include_js(name){
if(!js_isIncluded(name)){
YOUR_LAZY_LOADING_FUNCTION(name);
LOADED_JS[name]=true;
}
}
you can also get all script elements and check the src,my solution is better because it hase the speed and simplicity of an hash array and the script src has an absolute path even if you set it with a relative path.
you may also want to init the array with the scripts normally loaded(without lazy loading)on the page init to avoid double request.
For what it's worth, if you define the scripts as type="module", they will only be loaded and executed once.