performance

问题 I taught my self Powershell so I do not know everything about it. I need to search a database with the exact amount of lines I have put in (the database is predefined), it contains > 11800 entries. Can you please help me find what is making this slow? Code: $Dict = Get-Content "C:\Users\----\Desktop\Powershell Program\US.txt" if($Right -ne "") { $Comb = $Letter + $Right $total = [int]0 $F = "" do { $F = $Dict | Select-Object -Index $total if($F.Length -eq $Num) { if($F.Chars("0") + $F.Chars(

问题 I am looking for a way to generate some kind of hash for PHP object (generic solution, working with all classed, built-in and custom, if possible). SplObjectStorage::getHash is not what I'm looking for, as it will generate different hash for every instance of given class. To picture the problem, let's consider simple class: class A() { public $field; //public only for simplicity } and 2 instances of that class: $a = new A(); $a->field = 'b'; $b = new A(); $b->field = 'b'; Every built-in

问题 I have observed a very strange behavior when tuning SVM parameters with caret . When training a single model without tuning, SVM with radial basis kernel takes more time than SVM with linear kernel, which is expected. However, when tuning SVM with both kernels over the same penalty grid, SVM with linear kernel takes substantially more time than SVM with radial basis kernel. This behavior can be easily reproduced in both Windows and Linux with R 3.2 and caret 6.0-47. Does anyone know why

问题 This is my environments. Java - 1.7 by Oracle mongod v2.4.5 (in Mongolab) I found difference in performance of the two MongoDB driver(2.9.3 vs 2.11.2) When I run same code using each driver, 2.11.2 slower than 2.9.3. for(int i=0; i<1000; i++){ BasicDBObject doc = new BasicDBObject( "currentTime", new SimpleDateFormat("HH:mm:ss:SSS").format(Calendar.getInstance().getTime()) ); coll.insert(doc); } DBCursor cursor = coll.find(); try{ while(cursor.hasNext()){ System.out.println(cursor.next()); }

问题 I'm designing a method for an input handler class. Here is some pseudo code... void InputHandler::ScanEvents( boost::function1< void, std::string& > &func ) { // Scan keys, determining string to pass // If string found, call func with string as its argument on object tied to func } I'm not exactly sure how to implement this, or if it is even possible, since the whole point of a function is to separate it from its caller. The idea is that an object has a private member function and a boost:

问题 I'm designing a method for an input handler class. Here is some pseudo code... void InputHandler::ScanEvents( boost::function1< void, std::string& > &func ) { // Scan keys, determining string to pass // If string found, call func with string as its argument on object tied to func } I'm not exactly sure how to implement this, or if it is even possible, since the whole point of a function is to separate it from its caller. The idea is that an object has a private member function and a boost:

问题 There is a great question about the "as-if" rule in general, but I wonder if there are any excpetions when it comes to measuring time. Consider this (taken from here slightly modified): using std::chrono; auto begin = steady_clock::now(); auto result = some_lengthy_calculation(some_params); auto end= std::chrono::steady_clock::now(); std::cout << "Time diff = " << duration_cast<microseconds>(end - begin).count() <<std::endl; std::cout << "Result = " << result; The compiler is allowed to apply

问题 I want to replicate data from a boat offshore to an onshore site. The connection is sometimes via a satellite link and can be slow and have a high latency. Latency in our application is important, the people on-shore should have the data as soon as possible. There is one table being replicated, consisting of an id, datetime and some binary data that may vary in length, usually < 50 bytes. An application off-shore pushes data (hardware measurements) into the table constantly and we want these

问题 I want to replicate data from a boat offshore to an onshore site. The connection is sometimes via a satellite link and can be slow and have a high latency. Latency in our application is important, the people on-shore should have the data as soon as possible. There is one table being replicated, consisting of an id, datetime and some binary data that may vary in length, usually < 50 bytes. An application off-shore pushes data (hardware measurements) into the table constantly and we want these

问题 I want to replicate data from a boat offshore to an onshore site. The connection is sometimes via a satellite link and can be slow and have a high latency. Latency in our application is important, the people on-shore should have the data as soon as possible. There is one table being replicated, consisting of an id, datetime and some binary data that may vary in length, usually < 50 bytes. An application off-shore pushes data (hardware measurements) into the table constantly and we want these