performance

问题 The situation When writing high-performance JavaScript code, the standard profiling tools offered by Chrome et al are not always sufficient. They only seem to offer function-level granularity and it can be quite time-consuming to drill down and find the information I need. In .NET the StopWatch class gives me exactly what I need: sub-microsecond resolution timing of arbitrary pieces of code. For JavaScript performance.now() used to be a pretty good way to measure performance, but in response

问题 This question already has an answer here : In Lua, should I define a variable every iteration of a loop or before the loop? (1 answer) Closed 4 years ago . I am used to do this: do local a for i=1,1000000 do a = <some expression> <...> --do something with a end end instead of for i=1,1000000 do local a = <some expression> <...> --do something with a end My reasoning is that creating a local variable 1000000 times is less efficient than creating it just once and reuse it on each iteration. My

问题 If I have the array: {01101111,11110000,00001111} // {111, 240, 15} The result for a 1 bit shift is: {10110111,11111000,00000111} // {183, 248, 7} The array size is not fixed, and the shifting will be from 1 to 7 inclusive. Currently I have the following code (which works fine): private static void shiftBitsRight(byte[] bytes, final int rightShifts) { assert rightShifts >= 1 && rightShifts <= 7; final int leftShifts = 8 - rightShifts; byte previousByte = bytes[0]; // keep the byte before

问题 After about 90 seconds I see this error in my apache error log. I'm assusming I need to increase a setting in PHP but I'm not sure which one to change. Is there one setting I can increase to clear this error? 回答1: Find in your php.ini file something like this: ; Maximum execution time of each script, in seconds ; http://php.net/max-execution-time ; Note: This directive is hardcoded to 0 for the CLI SAPI max_execution_time = 600 ; Maximum amount of time each script may spend parsing request

问题 After about 90 seconds I see this error in my apache error log. I'm assusming I need to increase a setting in PHP but I'm not sure which one to change. Is there one setting I can increase to clear this error? 回答1: Find in your php.ini file something like this: ; Maximum execution time of each script, in seconds ; http://php.net/max-execution-time ; Note: This directive is hardcoded to 0 for the CLI SAPI max_execution_time = 600 ; Maximum amount of time each script may spend parsing request

问题 We are experiencing RSS that keeps on increasing in one of our Go service. We are suspecting it's due to scavenger not returning memory to OS properly (or OS not taking back the memory due to use of MADV_FREE). Checked via pprof, no memory leak detected. We tried some experiment with the following simple Go program: Go version: go1.13.4 linux/amd64 (tried with go1.13.1 too) package main import ( "fmt" "time" ) func allocate(s int) { a := make([]byte, s * 1024 * 1024) for i := 0;i < len(a); i

问题 Apologies if this is a duplicate - I did a few searches and didn't quite find what I need. We have a performance critical piece of our application that converts a Play 2.0 Enumerator (can be thought of as a Stream ) of incoming data to a List (or similar). We will use the fold method on Enumerator and the question is what will be the most performant way to do it. (I will use Stream instead of Enumerator in the code, but the idea should be the same.) val incoming: Stream[Int] = ??? val result:

问题 Apologies if this is a duplicate - I did a few searches and didn't quite find what I need. We have a performance critical piece of our application that converts a Play 2.0 Enumerator (can be thought of as a Stream ) of incoming data to a List (or similar). We will use the fold method on Enumerator and the question is what will be the most performant way to do it. (I will use Stream instead of Enumerator in the code, but the idea should be the same.) val incoming: Stream[Int] = ??? val result:

问题 We recently applied a caching solution that is used by almost all application modules/components (approx. 50 projects). To get a better understanding which cache operations are executed on the different system "places", we added logging for the currently performed cache operations including a stack trace to exactly know what triggered the cache operation. Our current approach looks like this: We take the stack trace from new Throwable(), filter the irrelevant lines and log the remaining stack

问题 We recently applied a caching solution that is used by almost all application modules/components (approx. 50 projects). To get a better understanding which cache operations are executed on the different system "places", we added logging for the currently performed cache operations including a stack trace to exactly know what triggered the cache operation. Our current approach looks like this: We take the stack trace from new Throwable(), filter the irrelevant lines and log the remaining stack