代码功能：循环拼接字符串，并替换子字符串硬件环境：Intel Core2 Duo T7500@2.20Ghz CPU; 2 GB RAM; OS Debian GNU/Linux 2.6.32 i686代码执行时长代码性能对比图最慢: Java gcj (native executable) 较慢: Java (openJDK); Java (Sun); Lua 稍慢: tcl; Javascript (spidermonkey) 较快: Python; Ruby; PHP; C++; Javascript V8; C; Perl5 最快的是Perl，最慢的gcj，你能接受吗？内存使用情况内存对比图：测试源码：C (source); Result: C gcc (Debian 4.4.4-1) 4.4.4#include#include #include #include int main(){setbuf(stdout,NULL); //disable output bufferingchar *str=malloc(8);strcpy(str,"abcdefgh");str=realloc(str,strlen(str)+8);strcat(str,"efghefgh"); //sprintf(str,"%s%s",str,"efghefgh");int imax=1024/strlen(str)*1024*4;printf("%s","exec.tm.sec\tstr.length\n"); //fflush(stdout);time_t starttime=time(NULL);char *gstr=malloc(0);int i=0;char *pos;int lngth;char *pos_c=gstr;int str_len=strlen(str); while(i++ < imax+1000){ lngth=strlen(str)*i; gstr=realloc(gstr,lngth+str_len); strcat(gstr,str); //sprintf(gstr,"%s%s",gstr,str); pos_c+=str_len; pos=gstr; while(pos=strstr(pos,"efgh")){ memcpy(pos,"____",4); } if(lngth % (1024*256)==0){ printf("%dsec\t\t%dkb\n",time(NULL)-starttime,lngth/1024); //fflush(stdout); } }//printf("%s\n",gstr);}C++ (source) Result: C++ g++ (Debian 4.4.3-7) 4.4.3#include #include #include using namespace std;main (){ string str = "abcdefgh"; str += "efghefgh"; int imax = 1024 /str.length() * 1024 *4; time_t currentTime = time(NULL); cout << "exec.tm.sec\tstr.length" << endl; string find= "efgh"; string replace ="____"; string gstr; int i=0; int length;// int end=0; // size_t end=0; while(i++ < imax +1000){ gstr += str; gstr = gstr; size_t start, sizeSearch=find.size(), end=0; while((start=gstr.find(find,end))!=string::npos){ end=start+sizeSearch; gstr.replace(start,sizeSearch,replace); } length = str.length()*i; if((length%(1024 * 256))==0){ cout << time(NULL) - currentTime << "sec\t\t" << length/1024 << "kb" << endl; } }// cout << gstr << endl;return 0;}Javascript (source); Results: Javascript (Spidermonkey – Mozilla) 1.8.0 pre-release 1 2007-10-03,Javascript (V8 – Chrome)#!/usr/local/bin/jsvar str = "abcdefgh"+"efghefgh";var imax = 1024 / str.length * 1024 * 4;var time = new Date();print("exec.tm.sec\tstr.length");var gstr = "";var i=0;var lngth;while (i++ < imax+1000) { gstr += str; gstr = gstr.replace(/efgh/g, "____"); lngth=str.length*i; if ((lngth % (1024*256)) == 0) { var curdate=new Date(); print(parseInt(((curdate.getTime()-time.getTime())/1000))+"sec\t\t"+lngth/1024+"kb"); }}Java (source) Results: Java (OpenJDK) “1.6.0 18″,Java (Sun) “1.6.0 16″,Java (gcj) (Debian 4.4.3-1) 4.4.3public class java_test { public static final void main(String[] args) throws Exception { String str = "abcdefgh"+"efghefgh"; int imax = 1024 / str.length() * 1024 * 4; long time = System.currentTimeMillis(); System.out.println("exec.tm.sec\tstr.length\tallocated memory:free memory:memory used"); Runtime runtime = Runtime.getRuntime(); System.out.println("0\t\t0\t\t"+runtime.totalMemory()/1024 +":"+ runtime.freeMemory()/1024+":"+(runtime.totalMemory()-runtime.freeMemory())/1024); String gstr = ""; int i=0; int lngth; while (i++ < imax+1000) { gstr += str; gstr = gstr.replaceAll("efgh", "____"); lngth=str.length()*i; if ((lngth % (1024*256)) == 0) { System.out.println(((System.currentTimeMillis()-time)/1000)+"sec\t\t"+lngth/1024+"kb\t\t"+runtime.totalMemory()/1024+":"+runtime.freeMemory()/1024+":"+(runtime.totalMemory()-runtime.freeMemory())/1024); } } }}Perl5 (source); Result: This is perl, v5.10.1#!/usr/bin/perl$|=1; #disable output buffering, this is necessary for proper output through pipemy $str='abcdefgh'.'efghefgh';my $imax=1024/length($str)*1024*4; # 4mbmy $starttime=time();print "exec.tm.sec\tstr.length\n";my $gstr='';my $i=0;while($i++ < $imax+1000){ #adding 1000 iterations to delay exit. This will allow to capture memory usage on last step $gstr.=$str; $gstr=~s/efgh/____/g; my $lngth=length($str)*$i; ## my $lngth=length($gstr); # Perhaps that would be a slower way print time()-$starttime,"sec\t\t",$lngth/1024,"kb\n" unless $lngth % (1024*256); #print out every 256kb}PHP (source); Result: PHP 5.3.1-5 with Suhosin-Patch (cgi-fcgi) Python3 (source); Result: Python 3.1.3#!/usr/bin/python3 -uimport reimport timeimport sysstr='abcdefgh'+'efghefgh'imax=1024/len(str)*1024*4 # 4mbstarttime=time.time();print "exec.tm.sec\tstr.length"sys.stdout.flush()gstr=''i=0while (i < imax+1000): i=i+1 gstr+=str gstr=re.sub('efgh','____',gstr) lngth=len(str)*i if(lngth % (1024*256) == 0): print int(time.time()-starttime),"sec\t\t",(lngth/1024),"kb" sys.stdout.flush()Ruby (source); Result: ruby 1.8.7#!/usr/bin/ruby$stdout.sync=true;str='abcdefgh'+'efghefgh';imax=1024/str.length*1024*4; # 4mbstarttime=Time.new;print("exec.tm.sec\tstr.length\n");gstr='';i=0;while i < imax+1000 i=i+1; gstr+=str; gstr=gstr.gsub(/efgh/, "____") lngth=str.length*i; if(lngth % (1024*256)==0) print(((Time.new-starttime).ceil).to_s+"sec\t\t",(lngth/1024).to_s,"kb\n"); endend#puts gstr;Lua (source); Result: Lua 5.1.4#!/usr/bin/luaio.stdout:setvbuf "no"; -- io.flush();str='abcdefgh'..'efghefgh';imax=1024/string.len(str)*1024*4; -- 4mbstarttime=os.time();print "exec.tm.sec\tstr.length";gstr='';i=0;while i < imax+1000 do i=i+1; gstr=gstr..str; gstr=string.gsub(gstr,"efgh","____"); lngth=string.len(str)*i; if(math.mod(lngth,1024*256)==0) then print(os.time()-starttime.."sec\t\t"..(lngth/1024).."kb"); endendtcl (source); Result: tcl 8.4.19#!/usr/bin/tclshset str "abcdefgh"append str "efghefgh"set imax [expr {1024/[string length $str]*1024*4}]set starttime [clock clicks -milliseconds]puts "exec.tm.sec\tstr.length";set gstr ""set i 0while {$i<[expr {$imax+1000}]} { incr i append gstr $str; regsub -all {efgh} $gstr ____ gstr set lngth [expr {[string length $str]*$i}] if {[expr {$lngth % (1024*256)}] == 0} { puts "[expr int([expr [clock clicks -milliseconds] - $starttime] / 1000)]sec\t\t[expr {$lngth/1024}]kb" }}exit结论各语言随着版本升级，也在不断优化，想要用好每个语言的特性，需要摸透她的脾气，这个需要不断的加深了解。选语言就像选恋人，情人眼里出西施，你中意的，就是最好的，所以对以上结果别太较真。转自：http://www.yinqisen.cn/blog-685.html