Each Java process has a pid, which you first need to find with the jps command. Once you have the pid, you can use jstat -gc [insert-pid-here] to find statistics of the behavior of the garbage collected heap. jstat -gccapacity [insert-pid-here] will present information about memory pool generation and space capabilities. jstat -gcutil [insert-pid-here] will … Read more
The following are rough guidelines and educated guesses based on experience. You should timeit or profile your concrete use case to get hard numbers, and those numbers may occasionally disagree with the below. A list comprehension is usually a tiny bit faster than the precisely equivalent for loop (that actually builds a list), most likely … Read more
A compiled list of possible sources of improvement are below: General Make use of a profiler to discover memory leaks and performance problems in your application. personally I suggest dotTrace Run your site in Release mode, not Debug mode, when in production, and also during performance profiling. Release mode is much faster. Debug mode can … Read more
loc: only work on index iloc: work on position at: get scalar values. It’s a very fast loc iat: Get scalar values. It’s a very fast iloc Also, at and iat are meant to access a scalar, that is, a single element in the dataframe, while loc and iloc are ments to access several elements … Read more
WebSockets isn’t intended to replace AJAX and is not strictly even a replacement for Comet/long-poll (although there are many cases where this makes sense). The purpose of WebSockets is to provide a low-latency, bi-directional, full-duplex and long-running connection between a browser and server. WebSockets opens up new application domains to browser applications that were not … Read more
In his talk The Performance of Everyday Things, Jeff Richter shows that calling a method by reflection is about 1000 times slower than calling it normally. Jeff’s tip: if you need to call the method multiple times, use reflection once to find it, then assign it to a delegate, and then call the delegate.
This should work: SELECT age, count(age) FROM Students GROUP by age If you need the id as well you could include the above as a sub query like so: SELECT S.id, S.age, C.cnt FROM Students S INNER JOIN (SELECT age, count(age) as cnt FROM Students GROUP BY age) C ON S.age = C.age
I would go with option A: String.Join(String.Empty, los.ToArray()); My reasoning is because the Join method was written for that purpose. In fact if you look at Reflector, you’ll see that unsafe code was used to really optimize it. The other two also WORK, but I think the Join function was written for this purpose, and … Read more
isset() is faster, but it’s not the same as array_key_exists(). array_key_exists() purely checks if the key exists, even if the value is NULL. Whereas isset() will return false if the key exist and value is NULL.
There is absolutely no difference in meaning or performance, in JavaScript or ActionScript. var is a directive for the parser, and not a command executed at run-time. If a particular identifier has been declared var once or more anywhere in a function body(*), then all use of that identifier in the block will be referring … Read more