大约有 3,000 项符合查询结果（耗时：0.0098秒） [XML]
实现一个简单的服务端推方案 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...时性较差。虽然可以通过加快轮询频率的方式来缓解这个问题，但相应付出的代价也不小：一来会使负载居高不下，二来也会让带宽捉襟见肘。
再来说说Long Polling，如果使用传统的LAMP技术去实现的话，大致如下所示：
Long Pol...
Select random lines from a file
...0 --file lines_78000000000.txt > /dev/null 0.02s user 0.01s system 80% cpu 0.047 total
The reason it is so fast, well I don't read the whole file and just move the file pointer 10 times and print the line after the pointer.
Gitlab Repo
Old attempt
First I needed a file of 78.000.000.000 lines:...
“register” keyword in C?
...
It tells the compiler to try to use a CPU register, instead of RAM, to store the variable. Registers are in the CPU and much faster to access than RAM. But it's only a suggestion to the compiler, and it may not follow through.
...
How to detect idle time in JavaScript elegantly?
...ls the function, rather than letting it sit idle by.
It doesn't catch zero CPU usage directly, but that is impossible, because executing a function causes CPU usage. And user inactivity eventually leads to zero CPU usage, so indirectly it does catch zero CPU usage.
...
微博为什么限制140字(附短信70字限制考) - 创意 - 清泛网 - 专注C/C++及内核技术
微博为什么限制140字(附短信70字限制考)问题的提出申请过那么多的微博，数申请网易微博的动机最不纯，因为它的字数限制不是传说中的140字，而是163个字。当年觉得很可爱，于是就注...问题的提出
申请过那么多的微博，数申...
Debug Error \"pure virtual function call\" 原因解析 - 更多技术 - 清泛...
...函数中抛出异常，不然，我们不得不面对以下两个严重的问题：
二次异常导致程序退出;
遗留下来的未完全销毁的对象与未完成的工作导致的后续问题
pure virtual function call就是这种情况。
但是理想与现实总是有差距的，...
How can I check if a Perl array contains a particular value?
...grep, hash...
any: 0 wallclock secs ( 0.67 usr + 0.00 sys = 0.67 CPU) @ 149253.73/s (n=100000)
first: 1 wallclock secs ( 0.63 usr + 0.01 sys = 0.64 CPU) @ 156250.00/s (n=100000)
grep: 42 wallclock secs (41.95 usr + 0.08 sys = 42.03 CPU) @ 2379.25/s (n=100000)
hash: 0 ...
Go > operators
...me extra work when the shift count is a number.
Shift instructions in x86 CPUs consider only 5 bits (6 bits on 64-bit x86 CPUs) of the shift count. In languages like C/C++, the shift operator translates into a single CPU instruction.
The following Go code
x := 10
y := uint(1025) // A big shift c...
Why is address zero used for the null pointer?
...
@GMan - You are correct. On early CPUs, memory address zero was special and had hardware protection against access from running software (in some cases it was the start of the reset vector, and modifying it could prevent the CPU from resetting or starting up)...
Difference between a theta join, equijoin and natural join
...0000
Component(PName, CName, Cost)
=============================
Laptop, CPU, 500
Laptop, hdd, 300
Laptop, case, 700
Car, wheels, 1000
The Cartesian product Product x Component will be - bellow or sql fiddle. You can see there are 12 rows = 3 x 4. Obviously, rows like "Laptop" with "w...