I want to instantiate a large number of StringProperty fields to put text values
(>100000). All in all my code performs well so far. I'm still trying to optimize my code as well as possible to harness the full power capabilities of my weak CPU (Intel Atom N2600, 1,6GHz, 2GByte Ram).
I'm calling the following method 100000 times and it takes some seconds
until all values are stored in my array of StringProperty.
public setData(int row, int numberOfCols, String data [][]) {
this.dataValue = new StringProperty[numberOfCols];
for(int i=0;i<numberOfCols;i++) dataValue[i] = new SimpleStringProperty(data[row][i]);
}
Is the method above good enough for intantiating fields and putting values?
Any alternative ideas of how to tweak the method above?
Related
I need to analyse one http event value which should not be greater than 30mins. & 95% event should belong to this bucket. If it fails send the alert.
My first concern is to get the right metrics in /actuator/prometheus
Steps I took:
As in every http request event, I am getting one integer value called eventMinute.
Using micrometer MeterRegistry, I tried below code
// MeterRegistry meterRegistry ...
meterRegistry.summary("MINUTES_ANALYSIS", tags);
where tag = EVENT_MINUTE which receives some integer value in each
http event.
But this way, it floods the metrics due to millions of event.
Guide me a way please, i am beginner to this. Thanks!!
The simplest solution (which I would recommend you start with) would be to just create 2 counters:
int theThing = //getTheThing()
if(theThing > 30) {
meterRegistry.counter("my.request.counter.abovethreshold").inc()
}
meterRegistry.counter("my.request.counter.total").inc()
You would increment the counter that matches your threshold and another that tracks all requests (or reuse another meter that does that for you).
Then it is simple to setup a chart or alarm:
my_request_counter_abovethreshold/my_request_counter_total < .95
(I didn't test the code. It might need a tiny bit of tweaking)
You'll be able to do a similar thing with DistributionSummary by setting various SLOs (I'm not familiar with them to be able to offer one), but start with something simple first and if it is sufficient, you won't need the other complexity.
There are certain ways to solve this problem
1 ; here is a function which receives tags, name of metrics and a value
public void createOrUpdateHistogram(String metricName, Map<String, String> stringTags, double numericValue)
{
DistributionSummary.builder(metricName)
.tags(tags)
//can enforce slo if required
.publishPercentileHistogram()
.minimumExpectedValue(1.0D) // can take this based on how you want your distibution
.maximumExpectedValue(30.0D)
.register(this.meterRegistry)
.record(numericValue);
}
then it produce metrics like
delta_bucket{mode="CURRENT",le="30.0",} 11.0
delta_bucket{mode="CURRENT", le="+Inf",} 11.0
so as infinte also hold the less than value, so subtract the le=30 from le=+Inf
Another ways could be
public void createOrUpdateHistogram(String metricName, Map<String, String> stringTags, double numericValue)
{
Timer.builder(metricName)
.tags(tags)
.publishPercentiles(new double[]{0.5D, 0.95D})
.publishPercentileHistogram()
.serviceLevelObjectives(new Duration[]{Duration.ofMinutes(30L)})
.minimumExpectedValue(Duration.ofMinutes(30L))
.maximumExpectedValue(Duration.ofMinutes(30L))
.register(this.meterRegistry)
.record((long)timeDifference, TimeUnit.MINUTES);
}
it will only have two le, the given time and +inf
it can be change based on our requirements also it gives us quantile.
My SwiftUI segmented control picker uses plain Int ".tag(1)" etc values for its selection.
CoreData only has Int16, Int32 & Int64 options to choose from, and with any of those options it seems my picker selection and CoreData refuse to talk to each other.
How is this (??simple??) task achieved please?
I've tried every numeric based option within CoreData including Int16-64, doubles and floats, all of them break my code or simply just don't work.
Picker(selection: $addDogVM.gender, label: Text("Gender?")) {
Text("Boy ♂").tag(1)
Text("?").tag(2)
Text("Girl ♀").tag(3)
}
I expected any of the 3 CoreData Int options to work out of the box, and to be compatible with the (standard) Int used by the picker.
Each element of a segmented control is represented by an index of type Int, and this index therefore commences at 0.
So using your example of a segmented control with three segments (for example: Boy ♂, ?, Girl ♀), each segment is represented by three indexes 0, 1 & 2.
If the user selects the segmented control that represents Girl ♀, then...
segmentedControl.selectedSegmentIndex = 2
When storing a value using Core Data framework, that is to be represented as a segmented control index in the UI, I therefore always commence with 0.
Everything you read from this point onwards is programmer preference - that is and to be clear - there are a number of ways to achieve the same outcome and you should choose one that best suits you and your coding style. Note also that this can be confusing for a newcomer, so I would encourage patience. My only advice, keep things as simple as possible until you've tested and debugged and tested enough to understand the differences.
So to continue:
The Apple Documentation states that...
...on 64-bit platforms, Int is the same size as Int64.
So in the Core Data model editor (.xcdatamodeld file), I choose to apply an Integer 64 attribute type for any value that will be used as an Int in my code.
Also, somewhere, some time ago, I read that if there is no reason to use Integer 16 or Integer 32, then default to the use of Integer 64 in object model graph. (I assume Integer 16 or Integer 32 are kept for backward compatibility.) If I find that reference I'll link it here.
I could write about the use of scalar attribute types here and manually writing your managed object subclass/es by selecting in the attribute inspector Class Codegen = Manual/None, but honestly I have decided such added detail will only complicate matters.
So your "automatically generated by Core Data" managed object subclass/es (NSManagedObject) will use the optional NSNumber? wrapper...
You will therefore need to convert your persisted/saved data in your code.
I do this in two places... when I access the data and when I persist the data.
(Noting I assume your entity is of type Dog and an instance exists of dog i.e. let dog = Dog())
// access
tempGender = dog.gender as? Int
// save
dog.gender = tempGender as NSNumber?
In between, I use a "temp" var property of type Int to work with the segmented control.
// temporary property to use with segmented control
private var tempGender: Int?
UPDATE
I do the last part a little differently now...
Rather than convert the data in code, I made a simple extension to my managed object subclass to execute the conversion. So rather than accessing the Core Data attribute directly and manipulating the data in code, now I instead use this convenience var.
extension Dog {
var genderAsInt: Int {
get {
guard let gender = self.gender else { return 0 }
return Int(truncating: gender)
}
set {
self.gender = NSNumber(value: newValue)
}
}
}
Your picker code...
Picker(selection: $addDogVM.genderAsInt, label: Text("Gender?")) {
Text("Boy ♂").tag(0)
Text("?").tag(1)
Text("Girl ♀").tag(2)
}
Any questions, ask in the comments.
I have a multithreaded program running some logic to come up with rows of data that I need to save in my grails (2.4.4) application. I am using a fixedthreadpool with 30 threads. The skeleton of my program is below. My expectation is that each thread calculates all the attributes and saves on a row in the table. However, the end result I am seeing is that there are some random rows that are not saved. Upon repeating this exercise, it is seen that a different set of rows are not saved in the table. So, overall, each time this is attempted a certain set of rows are NOT saved in table at all. GORMInstance.errors did not reveal any errors. So, I have no clue what is incorrect in this program.
ExecutorService exeSvc = Executors.newFixedThreadPool(30)
for (obj in list){
exeSvc.execute({-> finRunnable obj} as Callable)
}
Also, here's the runnable program that the above snippet invokes.
def finRunnable = {obj ->
for (item in LIST-1){
for (it in LIST-2){
for (i in LIST-3){
rowdata = calculateValues(item, it, i);
GORMInstance instance = new GORMInstance();
instance.withTransaction{
instance.attribute1=rowdata[0];
instance.attribute2=rowdata[1];
......so on..
instance.save(flush:true)/*without flush:true, I am
running into HeuristicCompletion exception. So I need it
here. */
}//endTransaction
}//forloop 3
}//forloop 2
}//forloop 1
}//runnable closure
I need to grab a large amount of data from one set of tables and SQLBulkInsert into another set...unfortunately the source tables are ALL varchar(max) and I would like the destination to be the correct type. Some tables are in the millions of rows...and (for far too pointless policital reasons to go into) we can't use SSIS.
On top of that, some "bool" values are stored as "Y/N", some "0/1", some "T/F" some "true/false" and finally some "on/off".
Is there a way to overload IDataReader to perform type conversion? Would need to be on a per-column basis I guess?
An alternative (and might be the best solution) is to put a mapper in place (perhaps AutoMapper or custom) and use EF to load from one object and map into the other? This would provoide a lot of control but also require a lot of boilerplate code for every property :(
In the end I wrote a base wrapper class to hold the SQLDataReader, and implementing the IDataReader methods just to call the SQLDataReader method.
Then inherit from the base class and override GetValue on a per-case basis, looking for the column names that need translating:
public override object GetValue(int i)
{
var landingColumn = GetName(i);
string landingValue = base.GetValue(i).ToString();
object stagingValue = null;
switch (landingColumn)
{
case "D4DTE": stagingValue = landingValue.FromStringDate(); break;
case "D4BRAR": stagingValue = landingValue.ToDecimal(); break;
default:
stagingValue = landingValue;
break;
}
return stagingValue;
}
Works well, is extensible, and very fast thanks to SQLBulkUpload. OK, so there's a small maintenance overhead, but since the source columns will very rarely change, this doesn't really affect anything.
I am trying to execute parallel functions on a list of objects using the new C# 4.0 Parallel.ForEach function. This is a very long maintenance process. I would like to make it execute in the order of the list so that I can stop and continue execution at the previous point. How do I do this?
Here is an example. I have a list of objects: a1 to a100. This is the current order:
a1, a51, a2, a52, a3, a53...
I want this order:
a1, a2, a3, a4...
I am OK with some objects being run out of order, but as long as I can find a point in the list where I can say that all objects before this point were run. I read the parallel programming csharp whitepaper and didn't see anything about it. There isn't a setting for this in the ParallelOptions class.
Do something like this:
int current = 0;
object lockCurrent = new object();
Parallel.For(0, list.Count,
new ParallelOptions { MaxDegreeOfParallelism = MaxThreads },
(ii, loopState) => {
// So the way Parallel.For works is that it chunks the task list up with each thread getting a chunk to work on...
// e.g. [1-1,000], [1,001- 2,000], [2,001-3,000] etc...
// We have prioritized our job queue such that more important tasks come first. So we don't want the task list to be
// broken up, we want the task list to be run in roughly the same order we started with. So we ignore tha past in
// loop variable and just increment our own counter.
int thisCurrent = 0;
lock (lockCurrent) {
thisCurrent = current;
current++;
}
dothework(list[thisCurrent]);
});
You can see how when you break out of the parallel for loop you will know the last list item to be executed, assuming you let all threads finish prior to breaking. I'm not a big fan of PLINQ or LINQ. I honestly don't see how writing LINQ/PLINQ leads to maintainable source code or readability.... Parallel.For is a much better solution.
If you use Parallel.Break to terminate the loop then you are guarenteed that all indices below the returned value will have been executed. This is about as close as you can get. The example here uses For but ForEach has similar overloads.
int n = ...
var result = new double[n];
var loopResult = Parallel.For(0, n, (i, loopState) =>
{
if (/* break condition is true */)
{
loopState.Break();
return;
}
result[i] = DoWork(i);
});
if (!loopResult.IsCompleted &&
loopResult.LowestBreakIteration.HasValue)
{
Console.WriteLine("Loop encountered a break at {0}",
loopResult.LowestBreakIteration.Value);
}
In a ForEach loop, an iteration index is generated internally for each element in each partition. Execution takes place out of order but after break you know that all the iterations lower than LowestBreakIteration will have been completed.
Taken from "Parallel Programming with Microsoft .NET" http://parallelpatterns.codeplex.com/
Available on MSDN. See http://msdn.microsoft.com/en-us/library/ff963552.aspx. The section "Breaking out of loops early" covers this scenario.
See also: http://msdn.microsoft.com/en-us/library/dd460721.aspx
For anyone else who comes across this question - if you're looping over an array or list (rather than an IEnumberable ), you can use the overload of Parallel.Foreach that gives the element index to maintain original order too.
string[] MyArray; // array of stuff to do parallel tasks on
string[] ProcessedArray = new string[MyArray.Length];
Parallel.ForEach(MyArray, (ArrayItem,loopstate,ArrayElementIndex) =>
{
string ProcessedArrayItem = TaskToDo(ArrayItem);
ProcessedArray[ArrayElementIndex] = ProcessedArrayItem;
});
As an alternate suggestion, you could record which object have been run and then filter the list when you resume exection to exclude the objects which have already run.
If this needs to be persistent across application restarts, you can store the ID's of the already executed objects (I assume here the objects have some unique identifier).
For anybody looking for a simple solution, I have posted 2 extension methods (one using PLINQ and one using Parallel.ForEach) as part of an answer to the following question:
Ordered PLINQ ForAll
Not sure if question was altered as my comment seems wrong.
Here improved, basically remind that parallel jobs run in out of your control order.
ea printing 10 numbers might result in 1,4,6,7,2,3,9,0.
If you like to stop your program and continue later.
Problems alike this usually endup in batching workloads.
And have some logging of what was done.
Say if you had to check 10.000 numbers for prime or so.
You could loop in batches of size 100, and have a prime log1, log2, log3
log1= 0..99
log2=100..199
Be sure to set some marker to know if a batch job was finished.
Its a general aprouch since the question isnt that exact either.